Add 'environment' package

This commit adds a new environment package that manages all calls to the
underlying operating system.

TODO.md

@@ -5,12 +5,10 @@
   - Why a factory?
   - First steps after provisioning
 
-
+- Use `environment.Dial()` and `environment.Listen()`
 - Move `provision_entrypoint.sh` into go
 - Enhance Snapshots
     - Export the Docker Images
 - Avoid running `docker compose` executable and shift it to a library
 - Move resolver code into this
-- Cleanup code: Have consistent error handling
-- Add a proper metadata / statistics server
 - Single Malt Mode: Support having a single instance only!

cmd/backup.go

@@ -1,12 +1,10 @@
 package cmd
 
 import (
-	"io/fs"
-	"os"
-
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/backup"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/FAU-CDI/wisski-distillery/pkg/targz"
 	"github.com/tkw1536/goprogram/exit"
@@ -59,7 +57,7 @@ func (bk backupC) Run(context wisski_distillery.Context) error {
 		}
 		defer func() {
 			logging.LogMessage(context.IOStream, "Removing snapshot staging directory")
-			os.RemoveAll(sPath)
+			dis.Environment.RemoveAll(sPath)
 		}()
 	} else {
 		// staging mode: use dest as a destination
@@ -73,8 +71,8 @@ func (bk backupC) Run(context wisski_distillery.Context) error {
 
 		// create the directory (if it doesn't already exist)
 		logging.LogMessage(context.IOStream, "Creating staging directory")
-		err = os.Mkdir(sPath, fs.ModePerm)
+		err = dis.Core.Environment.Mkdir(sPath, environment.DefaultDirPerm)
-		if !os.IsExist(err) && err != nil {
+		if !environment.IsExist(err) && err != nil {
 			return errSnapshotFailed.WithMessageF(err)
 		}
 		err = nil
@@ -86,7 +84,7 @@ func (bk backupC) Run(context wisski_distillery.Context) error {
 			Dest: sPath,
 			Auto: bk.Positionals.Dest == "",
 		})
-		backup.WriteReport(context.IOStream)
+		backup.WriteReport(dis.Core.Environment, context.IOStream)
 		return nil
 	}, context.IOStream, "Generating Backup")
 
@@ -108,7 +106,7 @@ func (bk backupC) Run(context wisski_distillery.Context) error {
 	if err := logging.LogOperation(func() error {
 		context.IOStream.Println(archivePath)
 
-		count, err = targz.Package(archivePath, sPath, func(dst, src string) {
+		count, err = targz.Package(dis.Core.Environment, archivePath, sPath, func(dst, src string) {
 			context.Printf("\033[2K\r%s", dst)
 		})
 		context.Println("")

cmd/blind_update.go

@@ -3,7 +3,7 @@ package cmd
 import (
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
-	"github.com/FAU-CDI/wisski-distillery/pkg/execx"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/tkw1536/goprogram/exit"
 )
 
@@ -47,7 +47,7 @@ func (bu blindUpdate) Run(context wisski_distillery.Context) error {
 
 		code, err := instance.Shell(context.IOStream, "/runtime/blind_update.sh")
 		if err != nil {
-			return errBlindUpdateFailed.WithMessageF(instance.Slug, execx.ExecCommandError)
+			return errBlindUpdateFailed.WithMessageF(instance.Slug, environment.ExecCommandError)
 		}
 		if code != 0 {
 			return errBlindUpdateFailed.WithMessageF(instance.Slug, code)

cmd/bootstrap.go

@@ -2,12 +2,12 @@ package cmd
 
 import (
 	"io/fs"
-	"os"
 	"path/filepath"
 
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/config"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/tkw1536/goprogram/exit"
@@ -67,11 +67,15 @@ var errBootstrapCreateFile = exit.Error{
 }
 
 func (bs bootstrap) Run(context wisski_distillery.Context) error {
+	// installation environment is the native environment!
+	// TODO: Should this be configurable?
+	var env environment.Native
+
 	root := bs.Directory
 
 	// check that we didn't get a different base directory
 	{
-		got, err := core.ReadBaseDirectory()
+		got, err := core.ReadBaseDirectory(env)
 		if err == nil && got != "" && got != root {
 			return errBootstrapDifferent.WithMessageF(got)
 		}
@@ -79,10 +83,10 @@ func (bs bootstrap) Run(context wisski_distillery.Context) error {
 
 	{
 		logging.LogMessage(context.IOStream, "Creating root deployment directory")
-		if err := os.MkdirAll(root, fs.ModeDir); err != nil {
+		if err := env.MkdirAll(root, environment.DefaultDirPerm); err != nil {
 			return errBootstrapFailedToCreateDirectory.WithMessageF(root)
 		}
-		if err := core.WriteBaseDirectory(root); err != nil {
+		if err := core.WriteBaseDirectory(env, root); err != nil {
 			return errBootstrapFailedToSaveDirectory.WithMessageF(root)
 		}
 		context.Println(root)
@@ -98,18 +102,18 @@ func (bs bootstrap) Run(context wisski_distillery.Context) error {
 	tpl.DefaultDomain = bs.Hostname
 
 	// and use thge defaults
-	if err := tpl.SetDefaults(); err != nil {
+	if err := tpl.SetDefaults(env); err != nil {
 		return errBootstrapWriteConfig.WithMessageF(err)
 	}
 
 	{
 		logging.LogMessage(context.IOStream, "Copying over wdcli executable")
-		exe, err := os.Executable()
+		exe, err := env.Executable()
 		if err != nil {
 			return errBoostrapFailedToCopyExe.WithMessageF(err)
 		}
 
-		err = fsx.CopyFile(wdcliPath, exe)
+		err = fsx.CopyFile(env, wdcliPath, exe)
 		if err != nil && err != fsx.ErrCopySameFile {
 			return errBoostrapFailedToCopyExe.WithMessageF(err)
 		}
@@ -117,9 +121,9 @@ func (bs bootstrap) Run(context wisski_distillery.Context) error {
 	}
 
 	{
-		if !fsx.IsFile(envPath) {
+		if !fsx.IsFile(env, envPath) {
 			if err := logging.LogOperation(func() error {
-				env, err := os.Create(envPath)
+				env, err := env.Create(envPath, environment.DefaultFilePerm)
 				if err != nil {
 					return err
 				}
@@ -133,7 +137,8 @@ func (bs bootstrap) Run(context wisski_distillery.Context) error {
 			if err := logging.LogOperation(func() error {
 
 				context.Println(tpl.SelfOverridesFile)
-				if err := os.WriteFile(
+				if err := environment.WriteFile(
+					env,
 					tpl.SelfOverridesFile,
 					core.DefaultOverridesJSON,
 					fs.ModePerm,
@@ -142,7 +147,8 @@ func (bs bootstrap) Run(context wisski_distillery.Context) error {
 				}
 
 				context.Println(tpl.AuthorizedKeys)
-				if err := os.WriteFile(
+				if err := environment.WriteFile(
+					env,
 					tpl.AuthorizedKeys,
 					core.DefaultAuthorizedKeys,
 					fs.ModePerm,
@@ -160,14 +166,14 @@ func (bs bootstrap) Run(context wisski_distillery.Context) error {
 
 	// re-read the configuration and print it!
 	logging.LogMessage(context.IOStream, "Configuration is now complete")
-	f, err := os.Open(envPath)
+	f, err := env.Open(envPath)
 	if err != nil {
 		return errBootstrapOpenConfig.WithMessageF(err)
 	}
 	defer f.Close()
 
 	var cfg config.Config
-	if err := cfg.Unmarshal(f); err != nil {
+	if err := cfg.Unmarshal(env, f); err != nil {
 		return errBootstrapOpenConfig.WithMessageF(err)
 	}
 	context.Println(cfg)

cmd/monday.go

@@ -1,10 +1,10 @@
 package cmd
 
 import (
-	"os"
-
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
+	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 )
 
@@ -29,13 +29,10 @@ func (monday) Description() wisski_distillery.Description {
 }
 
 func (monday monday) AfterParse() error {
-	_, err := os.Stat(monday.Positionals.GraphdbZip)
+	// TODO: Use a generic environment here!
-	if os.IsNotExist(err) {
+	if !fsx.IsFile(environment.Native{}, monday.Positionals.GraphdbZip) {
 		return errNoGraphDBZip.WithMessageF(monday.Positionals.GraphdbZip)
 	}
-	if err != nil {
-		return err
-	}
 	return nil
 }
 

cmd/provision.go

@@ -57,7 +57,7 @@ func (p provision) Run(context wisski_distillery.Context) error {
 
 	// check that the base directory does not exist
 	logging.LogMessage(context.IOStream, "Checking that base directory %s does not exist", instance.FilesystemBase)
-	if fsx.IsDirectory(instance.FilesystemBase) {
+	if fsx.IsDirectory(dis.Environment, instance.FilesystemBase) {
 		return errProvisionAlreadyExists.WithMessageF(slug)
 	}
 

cmd/purge.go

@@ -1,8 +1,6 @@
 package cmd
 
 import (
-	"os"
-
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/component/instances"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
@@ -73,7 +71,7 @@ func (p purge) Run(context wisski_distillery.Context) error {
 
 	// remove the filesystem
 	logging.LogMessage(context.IOStream, "Removing from filesystem %s", instance.FilesystemBase)
-	if err := os.RemoveAll(instance.FilesystemBase); err != nil {
+	if err := dis.Core.Environment.RemoveAll(instance.FilesystemBase); err != nil {
 		context.EPrintln(err)
 	}
 

cmd/rebuild.go

@@ -33,7 +33,9 @@ var errRebuildFailed = exit.Error{
 }
 
 func (rb rebuild) Run(context wisski_distillery.Context) error {
-	instances, err := context.Environment.Instances().Load(rb.Positionals.Slug...)
+	dis := context.Environment
+
+	instances, err := dis.Instances().Load(rb.Positionals.Slug...)
 	if err != nil {
 		return err
 	}
@@ -44,7 +46,7 @@ func (rb rebuild) Run(context wisski_distillery.Context) error {
 		logging.LogOperation(func() error {
 			s := instance.Barrel()
 			if err := logging.LogOperation(func() error {
-				return s.Install(context.IOStream, component.InstallationContext{})
+				return s.Install(dis.Core.Environment, context.IOStream, component.InstallationContext{})
 			}, context.IOStream, "Installing docker stack"); err != nil {
 				globalErr = err
 				return err

cmd/reserve.go

@@ -58,7 +58,7 @@ func (r reserve) Run(context wisski_distillery.Context) error {
 
 	// check that the base directory does not exist
 	logging.LogMessage(context.IOStream, "Checking that base directory %s does not exist", instance.FilesystemBase)
-	if fsx.IsDirectory(instance.FilesystemBase) {
+	if fsx.IsDirectory(dis.Environment, instance.FilesystemBase) {
 		return errProvisionAlreadyExists.WithMessageF(slug)
 	}
 
@@ -66,7 +66,7 @@ func (r reserve) Run(context wisski_distillery.Context) error {
 	s := instance.Reserve()
 	{
 		if err := logging.LogOperation(func() error {
-			return s.Install(context.IOStream, component.InstallationContext{})
+			return s.Install(dis.Core.Environment, context.IOStream, component.InstallationContext{})
 		}, context.IOStream, "Installing docker stack"); err != nil {
 			return err
 		}

cmd/snapshot.go

@@ -2,11 +2,11 @@ package cmd
 
 import (
 	"io/fs"
-	"os"
 
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
 	"github.com/FAU-CDI/wisski-distillery/internal/wisski"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/FAU-CDI/wisski-distillery/pkg/targz"
 	"github.com/tkw1536/goprogram/exit"
@@ -60,7 +60,7 @@ func (bi snapshot) Run(context wisski_distillery.Context) error {
 		}
 		defer func() {
 			logging.LogMessage(context.IOStream, "Removing snapshot staging directory")
-			os.RemoveAll(sPath)
+			dis.Core.Environment.RemoveAll(sPath)
 		}()
 	} else {
 		// staging mode: use dest as a destination
@@ -74,8 +74,8 @@ func (bi snapshot) Run(context wisski_distillery.Context) error {
 
 		// create the directory (if it doesn't already exist)
 		logging.LogMessage(context.IOStream, "Creating staging directory")
-		err = os.Mkdir(sPath, fs.ModePerm)
+		err = dis.Core.Environment.Mkdir(sPath, fs.ModePerm)
-		if !os.IsExist(err) && err != nil {
+		if !environment.IsExist(err) && err != nil {
 			return errSnapshotFailed.WithMessageF(err)
 		}
 		err = nil
@@ -92,7 +92,7 @@ func (bi snapshot) Run(context wisski_distillery.Context) error {
 		})
 
 		// write out the report, ignoring any errors!
-		sreport.WriteReport(context.IOStream)
+		sreport.WriteReport(dis.Core.Environment, context.IOStream)
 
 		return nil
 	}, context.IOStream, "Generating Snapshot")
@@ -115,7 +115,7 @@ func (bi snapshot) Run(context wisski_distillery.Context) error {
 	if err := logging.LogOperation(func() error {
 		context.IOStream.Println(archivePath)
 
-		count, err = targz.Package(archivePath, sPath, func(dst, src string) {
+		count, err = targz.Package(dis.Core.Environment, archivePath, sPath, func(dst, src string) {
 			context.Printf("\033[2K\r%s", dst)
 		})
 		context.Println("")

cmd/system_update.go

@@ -1,13 +1,12 @@
 package cmd
 
 import (
-	"os"
-
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
 	"github.com/FAU-CDI/wisski-distillery/internal/config"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
-	"github.com/FAU-CDI/wisski-distillery/pkg/execx"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
+	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/FAU-CDI/wisski-distillery/pkg/unpack"
 	"github.com/tkw1536/goprogram/exit"
@@ -43,13 +42,10 @@ var errNoGraphDBZip = exit.Error{
 }
 
 func (s systemupdate) AfterParse() error {
-	_, err := os.Stat(s.Positionals.GraphdbZip)
+	// TODO: Use a generic environment here!
-	if os.IsNotExist(err) {
+	if !fsx.IsFile(environment.Native{}, s.Positionals.GraphdbZip) {
 		return errNoGraphDBZip.WithMessageF(s.Positionals.GraphdbZip)
 	}
-	if err != nil {
-		return err
-	}
 	return nil
 }
 
@@ -85,7 +81,7 @@ func (si systemupdate) Run(context wisski_distillery.Context) error {
 		dis.SnapshotsArchivePath(),
 	} {
 		context.Println(d)
-		if err := os.MkdirAll(d, os.ModeDir); err != nil {
+		if err := dis.Core.Environment.MkdirAll(d, environment.DefaultDirPerm); err != nil {
 			return errBoostrapFailedToCreateDirectory.WithMessageF(d, err)
 		}
 	}
@@ -123,10 +119,10 @@ func (si systemupdate) Run(context wisski_distillery.Context) error {
 
 	if err := logging.LogOperation(func() error {
 		for _, component := range dis.Installables() {
-			stack := component.Stack()
+			stack := component.Stack(dis.Core.Environment)
 			ctx := component.Context(ctx)
 			if err := logging.LogOperation(func() error {
-				return stack.Install(context.IOStream, ctx)
+				return stack.Install(dis.Core.Environment, context.IOStream, ctx)
 			}, context.IOStream, "Installing docker stack %q", component.Name()); err != nil {
 				return err
 			}
@@ -143,7 +139,7 @@ func (si systemupdate) Run(context wisski_distillery.Context) error {
 	}
 
 	if err := logging.LogOperation(func() error {
-		return unpack.InstallDir(dis.Config.RuntimeDir(), "runtime", config.Runtime, func(dst, src string) {
+		return unpack.InstallDir(dis.Core.Environment, dis.Config.RuntimeDir(), "runtime", config.Runtime, func(dst, src string) {
 			context.Printf("[copy]  %s\n", dst)
 		})
 	}, context.IOStream, "Unpacking Runtime Components"); err != nil {
@@ -175,10 +171,11 @@ var errMustExecFailed = exit.Error{
 // mustExec indicates that the given executable process must complete successfully.
 // If it does not, returns errMustExecFailed
 func (si systemupdate) mustExec(context wisski_distillery.Context, workdir string, exe string, argv ...string) error {
+	dis := context.Environment
 	if workdir == "" {
 		workdir = context.Environment.Config.DeployRoot
 	}
-	code := execx.Exec(context.IOStream, workdir, exe, argv...)
+	code := dis.Core.Environment.Exec(context.IOStream, workdir, exe, argv...)
 	if code != 0 {
 		err := errMustExecFailed.WithMessageF(code)
 		err.ExitCode = exit.ExitCode(code)

cmd/update_prefix_config.go

@@ -1,11 +1,11 @@
 package cmd
 
 import (
-	"io/fs"
+	"io"
-	"os"
 
 	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/tkw1536/goprogram/exit"
 )
@@ -42,7 +42,7 @@ func (upc updateprefixconfig) Run(context wisski_distillery.Context) error {
 	target := ddis.ResolverConfigPath()
 
 	// print the configuration
-	config, err := os.OpenFile(target, os.O_WRONLY, fs.ModePerm)
+	config, err := dis.Core.Environment.Create(target, environment.DefaultFilePerm)
 	if err != nil {
 		return errPrefixUpdateFailed.WithMessageF(err)
 	}
@@ -58,7 +58,7 @@ func (upc updateprefixconfig) Run(context wisski_distillery.Context) error {
 			context.IOStream.Printf("%s", data)
 
 			// and write it out!
-			if _, err := config.WriteString(data); err != nil {
+			if _, err := io.WriteString(config, data); err != nil {
 				return err
 			}
 
@@ -70,7 +70,7 @@ func (upc updateprefixconfig) Run(context wisski_distillery.Context) error {
 
 	// and restart the resolver to apply the config!
 	logging.LogMessage(context.IOStream, "restarting resolver stack")
-	if err := ddis.Stack().Restart(context.IOStream); err != nil {
+	if err := ddis.Stack(ddis.Environment).Restart(context.IOStream); err != nil {
 		return errPrefixUpdateFailed.WithMessageF(err)
 	}
 

internal/backup/backup.go

@@ -2,14 +2,13 @@
 package backup
 
 import (
-	"io/fs"
-	"os"
 	"path/filepath"
 	"sync"
 	"time"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
 	"github.com/FAU-CDI/wisski-distillery/internal/wisski"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/tkw1536/goprogram/stream"
 	"golang.org/x/exp/slices"
@@ -61,6 +60,7 @@ func (backup *Backup) run(io stream.IOStream, dis *wisski.Distillery) {
 				err:  bc.Backup(context),
 			}
 		}(bc, &context{
+			env:   dis.Core.Environment,
 			io:    io,
 			dst:   filepath.Join(backup.Description.Dest, bc.BackupName()),
 			files: files,
@@ -73,7 +73,7 @@ func (backup *Backup) run(io stream.IOStream, dis *wisski.Distillery) {
 		defer wg.Done()
 
 		instancesBackupDir := filepath.Join(backup.Description.Dest, "instances")
-		if err := os.Mkdir(instancesBackupDir, fs.ModeDir); err != nil {
+		if err := dis.Core.Environment.Mkdir(instancesBackupDir, environment.DefaultDirPerm); err != nil {
 			backup.InstanceListErr = err
 			return
 		}
@@ -89,7 +89,7 @@ func (backup *Backup) run(io stream.IOStream, dis *wisski.Distillery) {
 		for i, instance := range instances {
 			backup.InstanceSnapshots[i] = func() wisski.Snapshot {
 				dir := filepath.Join(instancesBackupDir, instance.Slug)
-				if err := os.Mkdir(dir, fs.ModeDir); err != nil {
+				if err := dis.Core.Environment.Mkdir(dir, environment.DefaultDirPerm); err != nil {
 					return wisski.Snapshot{
 						ErrPanic: err,
 					}

internal/backup/context.go

@@ -3,16 +3,16 @@ package backup
 import (
 	"errors"
 	"io"
-	"io/fs"
-	"os"
 	"path/filepath"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/tkw1536/goprogram/stream"
 )
 
 // context implements [components.BackupContext]
 type context struct {
+	env   environment.Environment
 	io    stream.IOStream
 	dst   string      // destination directory
 	files chan string // files channel
@@ -54,7 +54,7 @@ func (bc *context) AddDirectory(path string, op func() error) error {
 	}
 
 	// run the make directory
-	if err := os.Mkdir(dst, fs.ModeDir); err != nil {
+	if err := bc.env.Mkdir(dst, environment.DefaultDirPerm); err != nil {
 		return err
 	}
 
@@ -72,7 +72,7 @@ func (bc *context) CopyFile(dst, src string) error {
 		return err
 	}
 	bc.sendPath(dst)
-	return fsx.CopyFile(dstPath, src)
+	return fsx.CopyFile(bc.env, dstPath, src)
 }
 
 func (bc *context) AddFile(path string, op func(file io.Writer) error) error {
@@ -83,7 +83,7 @@ func (bc *context) AddFile(path string, op func(file io.Writer) error) error {
 	}
 
 	// create the file
-	file, err := os.Create(dst)
+	file, err := bc.env.Create(dst, environment.DefaultFilePerm)
 	if err != nil {
 		return err
 	}

internal/backup/report.go

@@ -4,13 +4,13 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"os"
 	"path/filepath"
 	"strings"
 	"time"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/wisski"
 	"github.com/FAU-CDI/wisski-distillery/pkg/countwriter"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/tkw1536/goprogram/stream"
 )
@@ -96,20 +96,20 @@ func (backup Backup) Report(w io.Writer) (int, error) {
 
 // WriteReport writes out the report belonging to this backup.
 // It is a separate function, to allow writing it indepenently of the rest.
-func (backup Backup) WriteReport(io stream.IOStream) error {
+func (backup Backup) WriteReport(env environment.Environment, stream stream.IOStream) error {
 	return logging.LogOperation(func() error {
 		reportPath := filepath.Join(backup.Description.Dest, "report.txt")
-		io.Println(reportPath)
+		stream.Println(reportPath)
 
 		// create the report file!
-		report, err := os.Create(reportPath)
+		report, err := env.Create(reportPath, environment.DefaultFilePerm)
 		if err != nil {
 			return err
 		}
 		defer report.Close()
 
 		// print the report into it!
-		_, err = report.WriteString(backup.String())
+		_, err = io.WriteString(report, backup.String())
 		return err
-	}, io, "Writing backup report")
+	}, stream, "Writing backup report")
 }

internal/component/backup.go

@@ -28,8 +28,8 @@ type BackupContext interface {
 	// It then allows op to fill the file.
 	AddDirectory(path string, op func() error) error
 
-	// CopyFile copies a file from source to dst.
+	// CopyFile copies a file from src to dst.
-	CopyFile(dest, src string) error
+	CopyFile(dst, src string) error
 
 	// AddFile creates a new file at the provided path inside the destination.
 	// Passing the empty path creates the destination as a file.

internal/component/component.go

@@ -3,6 +3,7 @@ package component
 
 import (
 	"github.com/FAU-CDI/wisski-distillery/internal/config"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Component represents a logical subsystem of the distillery.
@@ -38,7 +39,7 @@ type Installable interface {
 	// Stack can be used to gain access to the "docker compose" stack.
 	//
 	// This should internally call [ComponentBase.MakeStack]
-	Stack() StackWithResources
+	Stack(env environment.Environment) StackWithResources
 
 	// Context returns a new InstallationContext to be used during installation from the command line.
 	// Typically this should just pass through the parent, but might perform other tasks.
@@ -47,8 +48,14 @@ type Installable interface {
 
 // ComponentBase implements base functionality for a component
 type ComponentBase struct {
-	Dir    string         // Dir is the directory this component lives in
+	Core        // the core of the associated distillery
-	Config *config.Config // Config is the configuration of the underlying distillery
+	Dir  string // Dir is the directory this component lives in
+}
+
+// Core represents the core of a distillery
+type Core struct {
+	Environment environment.Environment // environment to use for reading / writing to and from the distillery
+	Config      *config.Config          // the configuration of the distillery
 }
 
 // Base returns a reference to the ComponentBase
@@ -67,7 +74,8 @@ func (ComponentBase) Context(parent InstallationContext) InstallationContext {
 }
 
 // MakeStack registers the Installable as a stack
-func (cb ComponentBase) MakeStack(stack StackWithResources) StackWithResources {
+func (cb ComponentBase) MakeStack(env environment.Environment, stack StackWithResources) StackWithResources {
+	stack.Env = env
 	stack.Dir = cb.Dir
 	return stack
 }

internal/component/control/control.go

@@ -6,6 +6,7 @@ import (
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
 	"github.com/FAU-CDI/wisski-distillery/internal/component/instances"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Control represents the control server
@@ -24,8 +25,8 @@ func (control Control) Name() string {
 //go:embed all:control control.env
 var resources embed.FS
 
-func (control Control) Stack() component.StackWithResources {
+func (control Control) Stack(env environment.Environment) component.StackWithResources {
-	return control.ComponentBase.MakeStack(component.StackWithResources{
+	return control.ComponentBase.MakeStack(env, component.StackWithResources{
 		Resources:   resources,
 		ContextPath: "control",
 		EnvPath:     "control.env",
@@ -49,6 +50,6 @@ func (control Control) Stack() component.StackWithResources {
 
 func (control Control) Context(parent component.InstallationContext) component.InstallationContext {
 	return component.InstallationContext{
-		core.Executable: control.Config.CurrentExecutable(),
+		core.Executable: control.Config.CurrentExecutable(control.Environment), // TODO: Does this make sense?
 	}
 }

internal/component/control/resolver.go

@@ -2,7 +2,6 @@ package control
 
 import (
 	"fmt"
-	"os"
 	"path/filepath"
 	"regexp"
 
@@ -37,7 +36,7 @@ func (control Control) resolver(io stream.IOStream) (p wdresolve.ResolveHandler,
 
 	// open the prefix file
 	prefixFile := control.ResolverConfigPath()
-	fs, err := os.Open(prefixFile)
+	fs, err := control.Environment.Open(prefixFile)
 	io.Println("loading prefixes from ", prefixFile)
 	if err != nil {
 		return p, err

internal/component/control/self.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
-	"os"
 	"strings"
 
 	"github.com/tkw1536/goprogram/stream"
@@ -13,7 +12,7 @@ import (
 // self returns the handler for the self overrides
 func (control Control) self(io stream.IOStream) (redirect Redirect, err error) {
 	// open the overrides file
-	overrides, err := os.Open(control.Config.SelfOverridesFile)
+	overrides, err := control.Environment.Open(control.Config.SelfOverridesFile)
 	io.Printf("loading overrides from %q\n", control.Config.SelfOverridesFile)
 	if err != nil {
 		return redirect, err

internal/component/installable.go

@@ -2,9 +2,9 @@ package component
 
 import (
 	"io/fs"
-	"os"
 	"path/filepath"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/FAU-CDI/wisski-distillery/pkg/unpack"
 	"github.com/pkg/errors"
@@ -29,7 +29,7 @@ type StackWithResources struct {
 
 	CopyContextFiles []string // Files to copy from the installation context
 
-	MakeDirsPerm fs.FileMode // permission for diretories, defaults to fs.ModeDir
+	MakeDirsPerm fs.FileMode // permission for diretories, defaults to [environment.DefaultDirCreate]
 	MakeDirs     []string    // directories to ensure that exist
 
 	TouchFiles []string // Files to 'touch', i.e. ensure that exist; guaranteed to be run after MakeDirs
@@ -42,10 +42,11 @@ type InstallationContext map[string]string
 //
 // Installation is non-interactive, but will provide debugging output onto io.
 // InstallationContext
-func (is StackWithResources) Install(io stream.IOStream, context InstallationContext) error {
+func (is StackWithResources) Install(env environment.Environment, io stream.IOStream, context InstallationContext) error {
 	if is.ContextPath != "" {
 		// setup the base files
 		if err := unpack.InstallDir(
+			env,
 			is.Dir,
 			is.ContextPath,
 			is.Resources,
@@ -62,6 +63,7 @@ func (is StackWithResources) Install(io stream.IOStream, context InstallationCon
 	if is.EnvPath != "" && is.EnvContext != nil {
 		io.Printf("[config]  %s\n", envDest)
 		if err := unpack.InstallTemplate(
+			env,
 			envDest,
 			is.EnvContext,
 			is.EnvPath,
@@ -78,9 +80,9 @@ func (is StackWithResources) Install(io stream.IOStream, context InstallationCon
 
 		io.Printf("[make]    %s\n", dst)
 		if is.MakeDirsPerm == fs.FileMode(0) {
-			is.MakeDirsPerm = fs.ModeDir
+			is.MakeDirsPerm = environment.DefaultDirPerm
 		}
-		if err := os.MkdirAll(dst, is.MakeDirsPerm); err != nil {
+		if err := env.MkdirAll(dst, is.MakeDirsPerm); err != nil {
 			return err
 		}
 	}
@@ -98,7 +100,7 @@ func (is StackWithResources) Install(io stream.IOStream, context InstallationCon
 
 		// copy over file from context
 		io.Printf("[copy]    %s (from %s)\n", dst, src)
-		if err := fsx.CopyFile(dst, src); err != nil {
+		if err := fsx.CopyFile(env, dst, src); err != nil {
 			return errors.Wrapf(err, "Unable to copy file %s", src)
 		}
 	}
@@ -109,7 +111,7 @@ func (is StackWithResources) Install(io stream.IOStream, context InstallationCon
 		dst := filepath.Join(is.Dir, name)
 
 		io.Printf("[touch]   %s\n", dst)
-		if err := fsx.Touch(dst); err != nil {
+		if err := fsx.Touch(env, dst); err != nil {
 			return err
 		}
 	}

internal/component/instances/wisski_create.go

@@ -21,7 +21,7 @@ func (instances *Instances) Create(slug string) (wisski WissKI, err error) {
 	wisski.instances = instances
 
 	// make sure that the slug is valid!
-	slug, err = stringparser.ParseSlug(slug)
+	slug, err = stringparser.ParseSlug(instances.Environment, slug)
 	if err != nil {
 		return wisski, errInvalidSlug
 	}
@@ -70,7 +70,7 @@ func (wisski WissKI) Provision(io stream.IOStream) error {
 
 	// create the basic st!
 	st := wisski.Barrel()
-	if err := st.Install(io, component.InstallationContext{}); err != nil {
+	if err := st.Install(wisski.instances.Core.Environment, io, component.InstallationContext{}); err != nil {
 		return err
 	}
 

internal/component/instances/wisski_pathbuilders.go

@@ -2,12 +2,11 @@ package instances
 
 import (
 	"fmt"
-	"io/fs"
-	"os"
 	"path/filepath"
 
 	_ "embed"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/tkw1536/goprogram/stream"
 	"golang.org/x/exp/maps"
 	"golang.org/x/exp/slices"
@@ -51,7 +50,7 @@ func (wisski *WissKI) ExportPathbuilders(dest string) error {
 	for _, name := range names {
 		pbxml := []byte(pathbuilders[name])
 		name := filepath.Join(dest, fmt.Sprintf("%s.xml", name))
-		if err := os.WriteFile(name, pbxml, fs.ModePerm); err != nil {
+		if err := environment.WriteFile(wisski.instances.Core.Environment, name, pbxml, environment.DefaultFilePerm); err != nil {
 			return err
 		}
 	}

internal/component/instances/wisski_prefix.go

@@ -3,7 +3,6 @@ package instances
 import (
 	"errors"
 	"io"
-	"os"
 	"path/filepath"
 	"strings"
 
@@ -14,7 +13,7 @@ import (
 // NoPrefix checks if this WissKI instance is excluded from generating prefixes.
 // TODO: Move this to the database!
 func (wisski *WissKI) NoPrefix() bool {
-	return fsx.IsFile(filepath.Join(wisski.FilesystemBase, "prefixes.skip"))
+	return fsx.IsFile(wisski.instances.Environment, filepath.Join(wisski.FilesystemBase, "prefixes.skip"))
 }
 
 var errPrefixExecFailed = errors.New("PrefixConfig: Failed to call list_uri_prefixes")
@@ -41,8 +40,8 @@ func (wisski *WissKI) PrefixConfig() (config string, err error) {
 
 	// custom prefixes
 	prefixPath := filepath.Join(wisski.FilesystemBase, "prefixes")
-	if fsx.IsFile(prefixPath) {
+	if fsx.IsFile(wisski.instances.Environment, prefixPath) {
-		prefix, err := os.Open(prefixPath)
+		prefix, err := wisski.instances.Core.Environment.Open(prefixPath)
 		if err != nil {
 			return "", err
 		}

internal/component/instances/wisski_stack.go

@@ -2,7 +2,6 @@ package instances
 
 import (
 	"embed"
-	"io/fs"
 	"path/filepath"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
@@ -16,6 +15,7 @@ func (wisski WissKI) Barrel() component.StackWithResources {
 	return component.StackWithResources{
 		Stack: component.Stack{
 			Dir: wisski.FilesystemBase,
+			Env: wisski.instances.Environment,
 		},
 
 		Resources:   barrelResources,
@@ -35,8 +35,7 @@ func (wisski WissKI) Barrel() component.StackWithResources {
 			"GLOBAL_AUTHORIZED_KEYS_FILE": wisski.instances.Config.GlobalAuthorizedKeysFile,
 		},
 
-		MakeDirsPerm: fs.ModeDir | fs.ModePerm,
+		MakeDirs: []string{"data", ".composer"},
-		MakeDirs:     []string{"data", ".composer"},
 
 		TouchFiles: []string{
 			filepath.Join("data", "authorized_keys"),
@@ -52,6 +51,7 @@ func (wisski WissKI) Reserve() component.StackWithResources {
 	return component.StackWithResources{
 		Stack: component.Stack{
 			Dir: wisski.FilesystemBase,
+			Env: wisski.instances.Environment,
 		},
 
 		Resources:   reserveResources,

internal/component/sql/backup.go

@@ -17,7 +17,7 @@ func (*SQL) BackupName() string {
 func (sql *SQL) Backup(context component.BackupContext) error {
 	return context.AddFile("", func(file io.Writer) error {
 		io := context.IO().Streams(file, nil, nil, 0).NonInteractive()
-		code, err := sql.Stack().Exec(io, "sql", "mysqldump", "--all-databases")
+		code, err := sql.Stack(sql.Environment).Exec(io, "sql", "mysqldump", "--all-databases")
 		if err != nil {
 			return err
 		}

internal/component/sql/database.go

@@ -21,6 +21,7 @@ func (sql SQL) openDatabase(database string, config *gorm.Config) (*gorm.DB, err
 		DSN:               fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8&parseTime=True&loc=Local", sql.Config.MysqlAdminUser, sql.Config.MysqlAdminPassword, sql.ServerURL, database),
 		DefaultStringSize: 256,
 	}
+	// TODO: Use sql.Core.Environment.Dial
 
 	db, err := gorm.Open(mysql.New(cfg), config)
 	if err != nil {
@@ -63,7 +64,7 @@ func (sql SQL) OpenBookkeeping(silent bool) (*gorm.DB, error) {
 func (sql SQL) Snapshot(io stream.IOStream, dest io.Writer, database string) error {
 	io = io.Streams(dest, nil, nil, 0).NonInteractive()
 
-	code, err := sql.Stack().Exec(io, "sql", "mysqldump", "--databases", database)
+	code, err := sql.Stack(sql.Environment).Exec(io, "sql", "mysqldump", "--databases", database)
 	if err != nil {
 		return err
 	}
@@ -75,7 +76,7 @@ func (sql SQL) Snapshot(io stream.IOStream, dest io.Writer, database string) err
 
 // OpenShell executes a mysql shell command
 func (sql SQL) OpenShell(io stream.IOStream, argv ...string) (int, error) {
-	return sql.Stack().Exec(io, "sql", "mysql", argv...)
+	return sql.Stack(sql.Environment).Exec(io, "sql", "mysql", argv...)
 }
 
 // WaitShell waits for the sql database to be reachable via a docker-compose shell

internal/component/sql/sql.go

@@ -3,10 +3,10 @@ package sql
 import (
 	"context"
 	"embed"
-	"io/fs"
 	"time"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 type SQL struct {
@@ -25,12 +25,12 @@ func (SQL) Name() string {
 //go:embed all:sql
 var resources embed.FS
 
-func (ssh SQL) Stack() component.StackWithResources {
+func (ssh SQL) Stack(env environment.Environment) component.StackWithResources {
-	return ssh.ComponentBase.MakeStack(component.StackWithResources{
+	return ssh.ComponentBase.MakeStack(env, component.StackWithResources{
 		Resources:   resources,
 		ContextPath: "sql",
 
-		MakeDirsPerm: fs.ModeDir | fs.ModePerm,
+		MakeDirsPerm: environment.DefaultDirPerm,
 		MakeDirs: []string{
 			"data",
 		},

internal/component/ssh/ssh.go

@@ -4,6 +4,7 @@ import (
 	"embed"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 type SSH struct {
@@ -17,8 +18,8 @@ func (SSH) Name() string {
 //go:embed all:stack
 var resources embed.FS
 
-func (ssh SSH) Stack() component.StackWithResources {
+func (ssh SSH) Stack(env environment.Environment) component.StackWithResources {
-	return ssh.ComponentBase.MakeStack(component.StackWithResources{
+	return ssh.ComponentBase.MakeStack(env, component.StackWithResources{
 		Resources:   resources,
 		ContextPath: "stack",
 	})

internal/component/stack.go

@@ -6,7 +6,7 @@ import (
 	"bytes"
 	"errors"
 
-	"github.com/FAU-CDI/wisski-distillery/pkg/execx"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/tkw1536/goprogram/stream"
 )
 
@@ -18,6 +18,7 @@ import (
 type Stack struct {
 	Dir string // Directory this Stack is located in
 
+	Env              environment.Environment
 	DockerExecutable string // Path to the native docker executable to use
 }
 
@@ -101,7 +102,7 @@ func (ds Stack) Run(io stream.IOStream, autoRemove bool, service, command string
 
 	code, err := ds.compose(io, compose...)
 	if err != nil {
-		return execx.ExecCommandError, nil
+		return environment.ExecCommandError, nil
 	}
 	return code, nil
 }
@@ -175,10 +176,10 @@ func (ds Stack) Down(io stream.IOStream) error {
 func (ds Stack) compose(io stream.IOStream, args ...string) (int, error) {
 	if ds.DockerExecutable == "" {
 		var err error
-		ds.DockerExecutable, err = execx.LookPathAbs("docker")
+		ds.DockerExecutable, err = ds.Env.LookPathAbs("docker")
 		if err != nil {
-			return execx.ExecCommandError, err
+			return environment.ExecCommandError, err
 		}
 	}
-	return execx.Exec(io, ds.Dir, ds.DockerExecutable, append([]string{"compose"}, args...)...), nil
+	return ds.Env.Exec(io, ds.Dir, ds.DockerExecutable, append([]string{"compose"}, args...)...), nil
 }

internal/component/triplestore/database.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"mime/multipart"
+	"net"
 	"net/http"
 
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
@@ -61,6 +62,14 @@ func (ts Triplestore) OpenRaw(method, url string, body interface{}, bodyName str
 	}
 
 	// create the request object
+	client := &http.Client{
+		Transport: &http.Transport{
+			Dial: ts.Environment.Dial,
+			DialTLS: func(network, addr string) (net.Conn, error) {
+				return nil, errors.New("not implemented")
+			},
+		},
+	}
 	req, err := http.NewRequest(method, ts.BaseURL+url, reader)
 	if err != nil {
 		return nil, err
@@ -76,7 +85,7 @@ func (ts Triplestore) OpenRaw(method, url string, body interface{}, bodyName str
 	req.SetBasicAuth(ts.Config.TriplestoreAdminUser, ts.Config.TriplestoreAdminPassword)
 
 	// and send it
-	return http.DefaultClient.Do(req)
+	return client.Do(req)
 }
 
 // Wait waits for the connection to the Triplestore to succeed.

internal/component/triplestore/triplestore.go

@@ -3,11 +3,11 @@ package triplestore
 import (
 	"context"
 	"embed"
-	"io/fs"
 	"path/filepath"
 	"time"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 type Triplestore struct {
@@ -26,14 +26,13 @@ func (Triplestore) Name() string {
 //go:embed all:stack
 var resources embed.FS
 
-func (ts Triplestore) Stack() component.StackWithResources {
+func (ts Triplestore) Stack(env environment.Environment) component.StackWithResources {
-	return ts.ComponentBase.MakeStack(component.StackWithResources{
+	return ts.ComponentBase.MakeStack(env, component.StackWithResources{
 		Resources:   resources,
 		ContextPath: "stack",
 
 		CopyContextFiles: []string{"graphdb.zip"}, // TODO: Move into constant?
 
-		MakeDirsPerm: fs.ModeDir | fs.ModePerm,
 		MakeDirs: []string{
 			filepath.Join("data", "data"),
 			filepath.Join("data", "work"),

internal/component/web/web.go

@@ -4,6 +4,7 @@ import (
 	"embed"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/component"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Web implements the ingress gateway for the distillery.
@@ -17,11 +18,11 @@ func (Web) Name() string {
 	return "web"
 }
 
-func (web Web) Stack() component.StackWithResources {
+func (web Web) Stack(env environment.Environment) component.StackWithResources {
 	if web.Config.HTTPSEnabled() {
-		return web.stackHTTPS()
+		return web.stackHTTPS(env)
 	} else {
-		return web.stackHTTP()
+		return web.stackHTTP(env)
 	}
 }
 
@@ -29,8 +30,8 @@ func (web Web) Stack() component.StackWithResources {
 //go:embed web-https.env
 var httpsResources embed.FS
 
-func (web Web) stackHTTPS() component.StackWithResources {
+func (web Web) stackHTTPS(env environment.Environment) component.StackWithResources {
-	return web.MakeStack(component.StackWithResources{
+	return web.MakeStack(env, component.StackWithResources{
 		Resources:   httpsResources,
 		ContextPath: "web-https",
 		EnvPath:     "web-https.env",
@@ -45,8 +46,8 @@ func (web Web) stackHTTPS() component.StackWithResources {
 //go:embed web-http.env
 var httpResources embed.FS
 
-func (web Web) stackHTTP() component.StackWithResources {
+func (web Web) stackHTTP(env environment.Environment) component.StackWithResources {
-	return web.MakeStack(component.StackWithResources{
+	return web.MakeStack(env, component.StackWithResources{
 		Resources:   httpResources,
 		ContextPath: "web-http",
 		EnvPath:     "web-http.env",

internal/config/executable.go

@@ -1,10 +1,10 @@
 package config
 
 import (
-	"os"
 	"path/filepath"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 )
 
@@ -14,19 +14,19 @@ func (cfg Config) ExecutablePath() string {
 }
 
 // UsingDistilleryExecutable checks if the current process is using the distillery executable
-func (cfg Config) UsingDistilleryExecutable() bool {
+func (cfg Config) UsingDistilleryExecutable(env environment.Environment) bool {
-	exe, err := os.Executable()
+	exe, err := env.Executable()
 	if err != nil {
 		return false
 	}
-	return fsx.SameFile(exe, cfg.ExecutablePath())
+	return fsx.SameFile(env, exe, cfg.ExecutablePath())
 }
 
 // CurrentExecutable returns the path to the current executable being used.
 // When it does not exist, falls back to the default executable.
-func (cfg Config) CurrentExecutable() string {
+func (cfg Config) CurrentExecutable(env environment.Environment) string {
-	exe, err := os.Executable()
+	exe, err := env.Executable()
-	if err != nil || !fsx.IsFile(exe) {
+	if err != nil || !fsx.IsFile(env, exe) {
 		return cfg.ExecutablePath()
 	}
 	return exe

internal/config/read.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"reflect"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/envreader"
 	"github.com/FAU-CDI/wisski-distillery/pkg/stringparser"
 )
@@ -16,7 +17,7 @@ import (
 // When a key is missing, it is set to the default value.
 //
 // See also [stringparser.Parse].
-func (config *Config) Unmarshal(src io.Reader) error {
+func (config *Config) Unmarshal(env environment.Environment, src io.Reader) error {
 	// read all the values!
 	values, err := envreader.ReadAll(src)
 	if err != nil {
@@ -32,26 +33,26 @@ func (config *Config) Unmarshal(src io.Reader) error {
 		tField := tConfig.Field(i)
 		vField := vConfig.FieldByName(tField.Name)
 
-		env := tField.Tag.Get("env")
+		tEnv := tField.Tag.Get("env")
-		dflt := tField.Tag.Get("default")
+		tDefault := tField.Tag.Get("default")
-		parser := tField.Tag.Get("parser")
+		tParser := tField.Tag.Get("parser")
 
 		// skip it if it isn't loaded!
-		if env == "" {
+		if tEnv == "" {
 			continue
 		}
 
 		// read the value with a default
-		value, ok := values[env]
+		value, ok := values[tEnv]
 		if !ok || value == "" {
-			if dflt == "" {
+			if tDefault == "" {
 				continue
 			}
-			value = dflt
+			value = tDefault
 		}
 
 		// parse the value!
-		if err := stringparser.Parse(parser, value, vField); err != nil {
+		if err := stringparser.Parse(env, tParser, value, vField); err != nil {
 			return err
 		}
 	}

internal/config/template.go

@@ -7,6 +7,7 @@ import (
 	"reflect"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/hostname"
 	"github.com/FAU-CDI/wisski-distillery/pkg/password"
 	"github.com/FAU-CDI/wisski-distillery/pkg/unpack"
@@ -29,13 +30,13 @@ type Template struct {
 }
 
 // SetDefaults sets defaults on the template
-func (tpl *Template) SetDefaults() (err error) {
+func (tpl *Template) SetDefaults(env environment.Environment) (err error) {
 	if tpl.DeployRoot == "" {
 		tpl.DeployRoot = core.BaseDirectoryDefault
 	}
 
 	if tpl.DefaultDomain == "" {
-		tpl.DefaultDomain = hostname.FQDN()
+		tpl.DefaultDomain = hostname.FQDN(env)
 	}
 
 	if tpl.SelfOverridesFile == "" {

internal/core/meta.go

@@ -3,10 +3,11 @@ package core
 import (
 	"errors"
 	"io/fs"
-	"os"
 	"os/user"
 	"path/filepath"
 	"strings"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // MetaConfigFile is the path to a configuration file that contains the path to the last used wdcli executable.
@@ -33,7 +34,7 @@ var errReadBaseDirectoryEmpty = errors.New("ReadBaseDirectory: Directory is empt
 // Use [ParamsFromEnv] to initialize parameters completely.
 //
 // It does not perform any reading of files.
-func ReadBaseDirectory() (value string, err error) {
+func ReadBaseDirectory(env environment.Environment) (value string, err error) {
 	// get the path!
 	path, err := MetaConfigPath()
 	if err != nil {
@@ -41,7 +42,7 @@ func ReadBaseDirectory() (value string, err error) {
 	}
 
 	// read the meta config file!
-	contents, err := os.ReadFile(path)
+	contents, err := environment.ReadFile(env, path)
 	if err != nil {
 		return "", err
 	}
@@ -59,7 +60,7 @@ func ReadBaseDirectory() (value string, err error) {
 }
 
 // WriteBaseDirectory writes the base directory to the environment, or returns an error
-func WriteBaseDirectory(dir string) error {
+func WriteBaseDirectory(env environment.Environment, dir string) error {
 	// get the path!
 	path, err := MetaConfigPath()
 	if err != nil {
@@ -67,5 +68,5 @@ func WriteBaseDirectory(dir string) error {
 	}
 
 	// just put the directory inside it!
-	return os.WriteFile(path, []byte(dir), fs.ModePerm)
+	return environment.WriteFile(env, path, []byte(dir), fs.ModePerm)
 }

internal/core/params.go

@@ -1,8 +1,9 @@
 package core
 
 import (
-	"os"
 	"path/filepath"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Params are used to initialize the excutable.
@@ -15,9 +16,9 @@ type Params struct {
 func ParamsFromEnv() (params Params, err error) {
 
 	// try to read the base directory!
-	value, err := ReadBaseDirectory()
+	value, err := ReadBaseDirectory(environment.Native{}) // TODO: Are we sure about the native environment here?
 	switch {
-	case os.IsNotExist(err):
+	case environment.IsNotExist(err):
 		params.ConfigPath = BaseDirectoryDefault
 	case err == nil:
 		params.ConfigPath = value

internal/wisski/backup_prune.go

@@ -1,7 +1,6 @@
 package wisski
 
 import (
-	"os"
 	"path/filepath"
 	"time"
 
@@ -18,7 +17,7 @@ func (dis *Distillery) PruneBackups(io stream.IOStream) error {
 	sPath := dis.SnapshotsArchivePath()
 
 	// list all the files
-	entries, err := os.ReadDir(sPath)
+	entries, err := dis.Core.Environment.ReadDir(sPath)
 	if err != nil {
 		return err
 	}
@@ -44,7 +43,7 @@ func (dis *Distillery) PruneBackups(io stream.IOStream) error {
 		path := filepath.Join(sPath, entry.Name())
 		io.Printf("Removing %s cause it is older than %d days", path, dis.Config.MaxBackupAge)
 
-		if err := os.Remove(path); err != nil {
+		if err := dis.Core.Environment.Remove(path); err != nil {
 			return err
 		}
 	}

internal/wisski/component.go

@@ -58,7 +58,7 @@ func makeComponent[C component.Component](dis *Distillery, field *lazy.Lazy[C],
 		}
 
 		base := c.Base()
-		base.Config = dis.Config
+		base.Core = dis.Core
 		if base.Dir == "" {
 			base.Dir = filepath.Join(dis.Config.DeployRoot, "core", c.Name())
 		}

internal/wisski/distillery.go

@@ -3,16 +3,15 @@ package wisski
 import (
 	"context"
 
-	"github.com/FAU-CDI/wisski-distillery/internal/config"
+	"github.com/FAU-CDI/wisski-distillery/internal/component"
 )
 
 // Distillery represents a WissKI Distillery
 //
 // It is the main structure used to interact with different components.
 type Distillery struct {
-	// Config holds the configuration of the distillery.
+	// core holds the core of the distillery
-	// It is read directly from a configuration file.
+	component.Core
-	Config *config.Config
 
 	// Upstream holds information to connect to the various running
 	// distillery components.
@@ -25,7 +24,7 @@ type Distillery struct {
 	components
 }
 
-// Upstream are the upstream urls connecting to the various external components.
+// Upstream contains the configuration for accessing remote configuration.
 type Upstream struct {
 	SQL         string
 	Triplestore string

internal/wisski/init.go

@@ -1,10 +1,10 @@
 package wisski
 
 import (
-	"os"
+	"github.com/FAU-CDI/wisski-distillery/internal/component"
-
 	"github.com/FAU-CDI/wisski-distillery/internal/config"
 	"github.com/FAU-CDI/wisski-distillery/internal/core"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/tkw1536/goprogram/exit"
 )
 
@@ -21,6 +21,9 @@ var errOpenConfig = exit.Error{
 // NewDistillery creates a new distillery from the provided flags
 func NewDistillery(params core.Params, flags core.Flags, req core.Requirements) (dis *Distillery, err error) {
 	dis = &Distillery{
+		Core: component.Core{
+			Environment: environment.Native{},
+		},
 		Upstream: Upstream{
 			SQL:         "127.0.0.1:3306",
 			Triplestore: "127.0.0.1:7200",
@@ -34,7 +37,7 @@ func NewDistillery(params core.Params, flags core.Flags, req core.Requirements)
 	if flags.InternalInDocker {
 		dis.Upstream.SQL = "sql:3306"
 		dis.Upstream.Triplestore = "triplestore:7200"
-		params.ConfigPath = os.Getenv("CONFIG_PATH")
+		params.ConfigPath = dis.Core.Environment.GetEnv("CONFIG_PATH")
 	}
 
 	// if we don't need to load the config, there is nothing to do
@@ -52,7 +55,7 @@ func NewDistillery(params core.Params, flags core.Flags, req core.Requirements)
 	}
 
 	// open the config file!
-	f, err := os.Open(params.ConfigPath)
+	f, err := dis.Core.Environment.Open(params.ConfigPath)
 	if err != nil {
 		return nil, errOpenConfig.WithMessageF(err)
 	}
@@ -62,6 +65,6 @@ func NewDistillery(params core.Params, flags core.Flags, req core.Requirements)
 	dis.Config = &config.Config{
 		ConfigPath: cfg,
 	}
-	err = dis.Config.Unmarshal(f)
+	err = dis.Config.Unmarshal(dis.Core.Environment, f)
 	return
 }

internal/wisski/snapshot.go

@@ -4,8 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/fs"
-	"os"
 	"path/filepath"
 	"strings"
 	"time"
@@ -13,6 +11,7 @@ import (
 	"github.com/FAU-CDI/wisski-distillery/internal/bookkeeping"
 	"github.com/FAU-CDI/wisski-distillery/internal/component/instances"
 	"github.com/FAU-CDI/wisski-distillery/pkg/countwriter"
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/FAU-CDI/wisski-distillery/pkg/logging"
 	"github.com/FAU-CDI/wisski-distillery/pkg/opgroup"
@@ -42,7 +41,7 @@ func (dis *Distillery) SnapshotsArchivePath() string {
 // The path is guaranteed to not exist.
 func (dis *Distillery) NewSnapshotArchivePath(prefix string) (path string) {
 	// TODO: Consider moving these into a subdirectory with the provided prefix.
-	for path == "" || fsx.Exists(path) {
+	for path == "" || fsx.Exists(dis.Environment, path) {
 		name := dis.newSnapshotName(prefix) + ".tar.gz"
 		path = filepath.Join(dis.SnapshotsArchivePath(), name)
 	}
@@ -64,9 +63,9 @@ func (*Distillery) newSnapshotName(prefix string) string {
 // NewSnapshotStagingDir returns the path to a new snapshot directory.
 // The directory is guaranteed to have been freshly created.
 func (dis *Distillery) NewSnapshotStagingDir(prefix string) (path string, err error) {
-	for path == "" || os.IsExist(err) {
+	for path == "" || environment.IsExist(err) {
 		path = filepath.Join(dis.SnapshotsStagingPath(), dis.newSnapshotName(prefix))
-		err = os.Mkdir(path, os.ModeDir)
+		err = dis.Core.Environment.Mkdir(path, environment.DefaultFilePerm)
 	}
 	if err != nil {
 		path = ""
@@ -210,7 +209,7 @@ func (snapshot *Snapshot) makeBlackbox(io stream.IOStream, dis *Distillery, inst
 		bkPath := filepath.Join(snapshot.Description.Dest, "bookkeeping.txt")
 		files <- bkPath
 
-		info, err := os.Create(bkPath)
+		info, err := dis.Core.Environment.Create(bkPath, environment.DefaultFilePerm)
 		if err != nil {
 			return err
 		}
@@ -227,7 +226,7 @@ func (snapshot *Snapshot) makeBlackbox(io stream.IOStream, dis *Distillery, inst
 		fsPath := filepath.Join(snapshot.Description.Dest, filepath.Base(instance.FilesystemBase))
 
 		// copy over whatever is in the base directory
-		return fsx.CopyDirectory(fsPath, instance.FilesystemBase, func(dst, src string) {
+		return fsx.CopyDirectory(dis.Core.Environment, fsPath, instance.FilesystemBase, func(dst, src string) {
 			files <- dst
 		})
 	}, &snapshot.ErrFilesystem)
@@ -237,7 +236,7 @@ func (snapshot *Snapshot) makeBlackbox(io stream.IOStream, dis *Distillery, inst
 		tsPath := filepath.Join(snapshot.Description.Dest, instance.GraphDBRepository+".nq")
 		files <- tsPath
 
-		nquads, err := os.Create(tsPath)
+		nquads, err := dis.Core.Environment.Create(tsPath, environment.DefaultFilePerm)
 		if err != nil {
 			return err
 		}
@@ -253,7 +252,7 @@ func (snapshot *Snapshot) makeBlackbox(io stream.IOStream, dis *Distillery, inst
 		sqlPath := filepath.Join(snapshot.Description.Dest, snapshot.Instance.SqlDatabase+".sql")
 		files <- sqlPath
 
-		sql, err := os.Create(sqlPath)
+		sql, err := dis.Core.Environment.Create(sqlPath, environment.DefaultFilePerm)
 		if err != nil {
 			return err
 		}
@@ -279,7 +278,7 @@ func (snapshot *Snapshot) makeWhitebox(io stream.IOStream, dis *Distillery, inst
 		files <- pbPath
 
 		// create the directory!
-		if err := os.Mkdir(pbPath, fs.ModeDir); err != nil {
+		if err := dis.Core.Environment.Mkdir(pbPath, environment.DefaultDirPerm); err != nil {
 			return err
 		}
 
@@ -312,20 +311,20 @@ func (snapshot *Snapshot) waitGroup(io stream.IOStream, og *opgroup.OpGroup[stri
 
 // WriteReport writes out the report belonging to this snapshot.
 // It is a separate function, to allow writing it indepenently of the rest.
-func (snapshot Snapshot) WriteReport(io stream.IOStream) error {
+func (snapshot *Snapshot) WriteReport(env environment.Environment, stream stream.IOStream) error {
 	return logging.LogOperation(func() error {
 		reportPath := filepath.Join(snapshot.Description.Dest, "report.txt")
-		io.Println(reportPath)
+		stream.Println(reportPath)
 
 		// create the report file!
-		report, err := os.Create(reportPath)
+		report, err := env.Create(reportPath, environment.DefaultFilePerm)
 		if err != nil {
 			return err
 		}
 		defer report.Close()
 
 		// print the report into it!
-		_, err = report.WriteString(snapshot.String())
+		_, err = io.WriteString(report, snapshot.String())
 		return err
-	}, io, "Writing snapshot report")
+	}, stream, "Writing snapshot report")
 }

pkg/environment/environment.go

@@ -0,0 +1,58 @@
+package environment
+
+import (
+	"io"
+	"io/fs"
+	"net"
+	"time"
+
+	"github.com/tkw1536/goprogram/stream"
+)
+
+// Environment represents an environment that a program can run it.
+// It mostly mimics the interfaces of the [os] package.
+type Environment interface {
+	isEnv()
+
+	GetEnv(name string) string
+
+	Stat(path string) (fs.FileInfo, error)
+	Lstat(path string) (fs.FileInfo, error)
+
+	Readlink(path string) (string, error)
+	Symlink(oldname, newname string) error
+
+	ReadDir(name string) ([]fs.DirEntry, error)
+
+	Open(path string) (fs.File, error)
+	Chtimes(name string, atime time.Time, mtime time.Time) error
+	SameFile(f1, f2 fs.FileInfo) bool
+
+	Create(path string, mode fs.FileMode) (WritableFile, error)
+
+	Mkdir(path string, mode fs.FileMode) error
+	MkdirAll(path string, mode fs.FileMode) error
+
+	Remove(path string) error
+	RemoveAll(path string) error
+
+	WalkDir(root string, fn fs.WalkDirFunc) error
+
+	Abs(path string) (string, error)
+
+	Listen(network, address string) (net.Listener, error)
+	Dial(network, address string) (net.Conn, error)
+
+	Executable() (string, error)
+	Exec(io stream.IOStream, workdir string, exe string, argv ...string) int
+	LookPathAbs(name string) (string, error)
+}
+
+type WritableFile interface {
+	fs.File
+	io.Writer
+}
+
+func init() {
+	var _ Environment = Native{}
+}

pkg/environment/globals.go

@@ -0,0 +1,69 @@
+package environment
+
+import (
+	"bytes"
+	"io"
+	"io/fs"
+	"os"
+
+	"github.com/tkw1536/goprogram/stream"
+)
+
+// ExecCommandError is returned by Exec when a command could not be executed.
+// This typically hints that the executable cannot be found, but may have other causes.
+const ExecCommandError = 127
+
+// DefaultFilePerm is the default mode to use for files
+const DefaultFilePerm fs.FileMode = 0666
+
+// DefaultDirPerm is the default mode to use for directories
+const DefaultDirPerm fs.FileMode = os.ModeDir & fs.ModePerm
+
+// IsExist checks if the provided error represents a 'does not exist' errror
+func IsExist(err error) bool {
+	return os.IsExist(err)
+}
+
+// IsNotExist checks if the provided error represents a 'does exist' error
+func IsNotExist(err error) bool {
+	return os.IsNotExist(err)
+}
+
+// WriteFile is like [os.WriteFile].
+func WriteFile(env Environment, path string, data []byte, mode fs.FileMode) error {
+	handle, err := env.Create(path, mode)
+	if err != nil {
+		return err
+	}
+	defer handle.Close()
+
+	if _, err := handle.Write(data); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// ReadFile is like [os.ReadFile]
+func ReadFile(env Environment, path string) ([]byte, error) {
+	// open the file!
+	file, err := env.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	// copy everything into a buffer!
+	var buffer bytes.Buffer
+	if _, err := io.Copy(&buffer, file); err != nil {
+		return nil, err
+	}
+
+	// return the buffer contents!
+	return buffer.Bytes(), nil
+}
+
+// MustExec is like Exec, except that it returns true if the command exited successfully, and else false.
+func MustExec(env Environment, io stream.IOStream, workdir string, exe string, argv ...string) bool {
+	return env.Exec(io, workdir, exe, argv...) == 0
+}

pkg/environment/native_exec.go

@@ -1,5 +1,4 @@
-// Package execx defines extensions to the "os/exec" package
+package environment
-package execx
 
 import (
 	"os/exec"
@@ -7,15 +6,11 @@ import (
 	"github.com/tkw1536/goprogram/stream"
 )
 
-// ExecCommandError is returned by Exec when a command could not be executed.
-// This typically hints that the executable cannot be found, but may have other causes.
-const ExecCommandError = 127
-
 // Exec executes a system command with the specified input/output streams, working directory, and arguments.
 //
 // If the command executes, it's exit code will be returned.
 // If the command can not be executed, returns [ExecCommandError].
-func Exec(io stream.IOStream, workdir string, exe string, argv ...string) int {
+func (Native) Exec(io stream.IOStream, workdir string, exe string, argv ...string) int {
 	// setup the command
 	cmd := exec.Command(exe, argv...)
 	cmd.Dir = workdir
@@ -40,7 +35,10 @@ func Exec(io stream.IOStream, workdir string, exe string, argv ...string) int {
 	return 0
 }
 
-// MustExec is like Exec, except that it returns true if the command exited successfully, and else false.
+func (n Native) LookPathAbs(file string) (string, error) {
-func MustExec(io stream.IOStream, workdir string, exe string, argv ...string) bool {
+	path, err := exec.LookPath(file)
-	return Exec(io, workdir, exe, argv...) == 0
+	if err != nil {
+		return "", err
+	}
+	return n.Abs(path)
 }

pkg/environment/native_fs.go

@@ -0,0 +1,80 @@
+package environment
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+type Native struct{}
+
+func (Native) isEnv() {}
+
+func (Native) GetEnv(name string) string {
+	return os.Getenv(name)
+}
+
+func (Native) Stat(path string) (fs.FileInfo, error) {
+	return os.Stat(path)
+}
+
+func (Native) Lstat(path string) (fs.FileInfo, error) {
+	return os.Lstat(path)
+}
+
+func (Native) Readlink(path string) (string, error) {
+	return os.Readlink(path)
+}
+
+func (Native) Symlink(oldname, newname string) error {
+	return os.Symlink(oldname, newname)
+}
+
+func (Native) ReadDir(name string) ([]fs.DirEntry, error) {
+	return os.ReadDir(name)
+}
+
+func (Native) SameFile(f1, f2 fs.FileInfo) bool {
+	return os.SameFile(f1, f2)
+}
+
+func (Native) WalkDir(path string, f fs.WalkDirFunc) error {
+	return filepath.WalkDir(path, f)
+}
+
+func (Native) Executable() (string, error) {
+	return os.Executable() // TODO: not sure this works with the remote concepts
+}
+
+func (Native) Open(path string) (fs.File, error) {
+	return os.Open(path)
+}
+
+func (Native) Create(path string, mode fs.FileMode) (WritableFile, error) {
+	return os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode)
+}
+
+func (Native) Chtimes(name string, atime time.Time, mtime time.Time) error {
+	return os.Chtimes(name, atime, mtime)
+}
+
+func (Native) Mkdir(path string, mode fs.FileMode) error {
+	return os.Mkdir(path, mode)
+}
+
+func (Native) MkdirAll(path string, mode fs.FileMode) error {
+	return os.MkdirAll(path, mode)
+}
+
+func (Native) Remove(path string) error {
+	return os.Remove(path)
+}
+
+func (Native) RemoveAll(path string) error {
+	return os.RemoveAll(path)
+}
+
+func (Native) Abs(path string) (string, error) {
+	return filepath.Abs(path)
+}

pkg/environment/native_net.go

@@ -0,0 +1,11 @@
+package environment
+
+import "net"
+
+func (Native) Listen(network, address string) (net.Listener, error) {
+	return net.Listen(network, address)
+}
+
+func (Native) Dial(network, address string) (net.Conn, error) {
+	return net.Dial(network, address)
+}

pkg/execx/look.go

@@ -1,15 +0,0 @@
-package execx
-
-import (
-	"os/exec"
-	"path/filepath"
-)
-
-// LookPathAbs is like [exec.LookPath], but always returns an absolute path
-func LookPathAbs(file string) (string, error) {
-	path, err := exec.LookPath(file)
-	if err != nil {
-		return "", err
-	}
-	return filepath.Abs(path)
-}

pkg/fsx/copy.go

@@ -4,8 +4,9 @@ import (
 	"errors"
 	"io"
 	"io/fs"
-	"os"
 	"path/filepath"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 var ErrCopySameFile = errors.New("src and dst must be different")
@@ -14,13 +15,13 @@ var ErrCopySameFile = errors.New("src and dst must be different")
 // When src points to a symbolic link, will copy the symbolic link.
 //
 // When dst and src are the same file, returns ErrCopySameFile.
-func CopyFile(dst, src string) error {
+func CopyFile(env environment.Environment, dst, src string) error {
-	if SameFile(src, dst) {
+	if SameFile(env, src, dst) {
 		return ErrCopySameFile
 	}
 
 	// open the source
-	srcFile, err := os.Open(src)
+	srcFile, err := env.Open(src)
 	if err != nil {
 		return err
 	}
@@ -33,7 +34,7 @@ func CopyFile(dst, src string) error {
 	}
 
 	// open or create the destination
-	dstFile, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE, srcStat.Mode())
+	dstFile, err := env.Create(dst, srcStat.Mode())
 	if err != nil {
 		return err
 	}
@@ -46,27 +47,27 @@ func CopyFile(dst, src string) error {
 
 // CopyLink copies a link from src to dst.
 // If dst already exists, it is deleted and then re-created.
-func CopyLink(dst, src string) error {
+func CopyLink(env environment.Environment, dst, src string) error {
 	// if they're the same file that is an error
-	if SameFile(dst, src) {
+	if SameFile(env, dst, src) {
 		return ErrCopySameFile
 	}
 
 	// read the link target
-	target, err := os.Readlink(src)
+	target, err := env.Readlink(src)
 	if err != nil {
 		return err
 	}
 
 	// delete it if it already exists
-	if Exists(dst) {
+	if Exists(env, dst) {
-		if err := os.Remove(dst); err != nil {
+		if err := env.Remove(dst); err != nil {
 			return err
 		}
 	}
 
 	// make the symbolic link!
-	return os.Symlink(target, dst)
+	return env.Symlink(target, dst)
 }
 
 var ErrDstFile = errors.New("dst is a file")
@@ -77,16 +78,16 @@ var ErrDstFile = errors.New("dst is a file")
 // When a directory already exists, additional files are not deleted.
 //
 // onCopy, when not nil, is called for each file or directory being copied.
-func CopyDirectory(dst, src string, onCopy func(dst, src string)) error {
+func CopyDirectory(env environment.Environment, dst, src string, onCopy func(dst, src string)) error {
 	// sanity checks
-	if SameFile(src, dst) {
+	if SameFile(env, src, dst) {
 		return ErrCopySameFile
 	}
-	if IsFile(dst) {
+	if IsFile(env, dst) {
 		return ErrDstFile
 	}
 
-	return filepath.WalkDir(src, func(path string, d fs.DirEntry, err error) error {
+	return env.WalkDir(src, func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}
@@ -111,19 +112,19 @@ func CopyDirectory(dst, src string, onCopy func(dst, src string)) error {
 		}
 
 		// if we have a symbolic link, copy the link!
-		if info.Mode()&os.ModeSymlink != 0 {
+		if info.Mode()&fs.ModeSymlink != 0 {
-			return CopyLink(dst, path)
+			return CopyLink(env, dst, path)
 		}
 
 		// if we got a file, we should copy it normally
 		if !d.IsDir() {
-			return CopyFile(dst, path)
+			return CopyFile(env, dst, path)
 		}
 
 		// create the directory, but ignore an error if the directory already exists.
 		// this is so that we can copy one tree into another tree.
-		err = os.Mkdir(dst, info.Mode())
+		err = env.Mkdir(dst, info.Mode())
-		if os.IsExist(err) && IsDirectory(dst) {
+		if environment.IsExist(err) && IsDirectory(env, dst) {
 			err = nil
 		}
 

pkg/fsx/same.go

@@ -1,17 +1,18 @@
 package fsx
 
 import (
-	"os"
 	"path/filepath"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // SameFile checks if path1 and path2 refer to the same file.
-// If both files exist, they are compared using [os.SameFile].
+// If both files exist, they are compared using [env.SameFile].
 // If both files do not exist, the paths are first compared syntactically and then via recursion on [filepath.Dir].
-func SameFile(path1, path2 string) bool {
+func SameFile(env environment.Environment, path1, path2 string) bool {
 
 	// initial attempt: check if directly
-	same, certain := couldBeSameFile(path1, path2)
+	same, certain := couldBeSameFile(env, path1, path2)
 	if certain {
 		return same
 	}
@@ -28,28 +29,28 @@ func SameFile(path1, path2 string) bool {
 
 	// compare the base names!
 	{
-		same, _ := couldBeSameFile(d1, d2)
+		same, _ := couldBeSameFile(env, d1, d2)
 		return same
 	}
 }
 
 // couldBeSameFile checks if path1 might be the same as path2.
 //
-// If both files exist, compares using [os.SameFile].
+// If both files exist, compares using [env.SameFile].
 // Otherwise compares absolute paths using string comparison.
 //
 // same indicates if they might be the same file.
 // authorative indiciates if the result is authorative.
-func couldBeSameFile(path1, path2 string) (same, authorative bool) {
+func couldBeSameFile(env environment.Environment, path1, path2 string) (same, authorative bool) {
 	{
 		// stat both files
-		info1, err1 := os.Stat(path1)
+		info1, err1 := env.Stat(path1)
-		info2, err2 := os.Stat(path2)
+		info2, err2 := env.Stat(path2)
 
-		// both files exist => check using os.SameFile
+		// both files exist => check using env.SameFile
 		// the result is always authorative
 		if err1 == nil && err2 == nil {
-			same = os.SameFile(info1, info2)
+			same = env.SameFile(info1, info2)
 			authorative = true
 			return
 		}
@@ -60,15 +61,15 @@ func couldBeSameFile(path1, path2 string) (same, authorative bool) {
 		}
 
 		// only 1 file does not exist => they could be different
-		if os.IsNotExist(err1) != os.IsNotExist(err2) {
+		if environment.IsNotExist(err1) != environment.IsNotExist(err2) {
 			return
 		}
 	}
 
 	{
 		// resolve paths absolutely
-		rpath1, err1 := filepath.Abs(path1)
+		rpath1, err1 := env.Abs(path1)
-		rpath2, err2 := filepath.Abs(path2)
+		rpath2, err2 := env.Abs(path2)
 
 		// if either path could not be resolved absolutely
 		// fallback to just using clean!

pkg/fsx/touch.go

@@ -1,20 +1,21 @@
 package fsx
 
 import (
-	"os"
 	"time"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Touch touches a file.
 // It is similar to the unix 'touch' command.
 //
-// If the file does not exist exists, it is created using [os.Create].
+// If the file does not exist exists, it is created using [env.Create].
 // If the file does exist, it's access and modification times are updated to the current time.
-func Touch(path string) error {
+func Touch(env environment.Environment, path string) error {
-	_, err := os.Stat(path)
+	_, err := env.Stat(path)
 	switch {
-	case os.IsNotExist(err):
+	case environment.IsNotExist(err):
-		f, err := os.Create(path)
+		f, err := env.Create(path, environment.DefaultFilePerm)
 		if err != nil {
 			return err
 		}
@@ -24,6 +25,6 @@ func Touch(path string) error {
 		return err
 	default:
 		now := time.Now().Local()
-		return os.Chtimes(path, now, now)
+		return env.Chtimes(path, now, now)
 	}
 }

pkg/fsx/type.go

@@ -2,29 +2,31 @@
 package fsx
 
 import (
-	"os"
+	"io/fs"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Exists checks if the given path exists
-func Exists(path string) bool {
+func Exists(env environment.Environment, path string) bool {
-	_, err := os.Lstat(path)
+	_, err := env.Lstat(path)
 	return err == nil
 }
 
 // IsDirectory checks if the provided path exists and is a directory
-func IsDirectory(path string) bool {
+func IsDirectory(env environment.Environment, path string) bool {
-	info, err := os.Stat(path)
+	info, err := env.Stat(path)
 	return err == nil && info.Mode().IsDir()
 }
 
 // IsFile checks if the provided path exists and is a regular file
-func IsFile(path string) bool {
+func IsFile(env environment.Environment, path string) bool {
-	info, err := os.Stat(path)
+	info, err := env.Stat(path)
 	return err == nil && info.Mode().IsRegular()
 }
 
 // IsLink checks if the provided path exists and is a symlink
-func IsLink(path string) bool {
+func IsLink(env environment.Environment, path string) bool {
-	info, err := os.Lstat(path)
+	info, err := env.Lstat(path)
-	return err == nil && info.Mode()&os.ModeSymlink != 0
+	return err == nil && info.Mode()&fs.ModeSymlink != 0
 }

pkg/hostname/hostname.go

@@ -4,12 +4,14 @@ package hostname
 import (
 	"os"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/Showmax/go-fqdn"
 )
 
 // FQDN attempts to return the fully qualified domain name of the host system.
 // If an error occurs, may fall back to the empty string.
-func FQDN() string {
+func FQDN(env environment.Environment) string {
+	// TODO: Pass this through!
 
 	// try the hostname function
 	{

pkg/stringparser/parse.go

@@ -4,11 +4,12 @@ import (
 	"reflect"
 	"strings"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/pkg/errors"
 )
 
 // Parse parses the provided value with the parser.
-func Parse(name, value string, vField reflect.Value) error {
+func Parse(env environment.Environment, name, value string, vField reflect.Value) error {
 
 	// use the validator
 	parser, ok := knownParsers[strings.ToLower(name)]
@@ -17,7 +18,7 @@ func Parse(name, value string, vField reflect.Value) error {
 	}
 
 	// get the parsed value
-	checked, err := parser(value)
+	checked, err := parser(env, value)
 	if err != nil {
 		return errors.Wrapf(err, "parser %s returned error", name)
 	}
@@ -53,8 +54,8 @@ var knownParsers map[string]Parser[any] = map[string]Parser[any]{
 }
 
 func asGenericParser[T any](parser Parser[T]) Parser[any] {
-	return func(s string) (value any, err error) {
+	return func(env environment.Environment, s string) (value any, err error) {
-		value, err = parser(s)
+		value, err = parser(env, s)
 		return
 	}
 }

pkg/stringparser/stringparser.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
 	"github.com/pkg/errors"
 )
@@ -17,19 +18,19 @@ import (
 // Parsers can be found in this package as functions called Parse*.
 // They are refered to by their name, e.g. ParseNonempty can be refered to by the name 'Nonempty'.
 // See [Parse].
-type Parser[T any] func(s string) (T, error)
+type Parser[T any] func(env environment.Environment, s string) (T, error)
 
 // ParseAbspath checks that s is an absolute path and returns it as-is
-func ParseAbspath(s string) (string, error) {
+func ParseAbspath(env environment.Environment, s string) (string, error) {
-	if !fsx.IsDirectory(s) {
+	if !fsx.IsDirectory(env, s) {
 		return "", errors.Errorf("%q does not exist or is not a directory", s)
 	}
 	return s, nil
 }
 
 // ParseFile checks that s is a valid file and returns it as-is
-func ParseFile(s string) (string, error) {
+func ParseFile(env environment.Environment, s string) (string, error) {
-	if !fsx.IsFile(s) {
+	if !fsx.IsFile(env, s) {
 		return "", errors.Errorf("%q does not exist or is not a regular file", s)
 	}
 	return s, nil
@@ -38,7 +39,7 @@ func ParseFile(s string) (string, error) {
 var errEmptyString = errors.New("value is empty")
 
 // ParseNonEmpty checks that s is a non-empty string and returns it as-is
-func ParseNonEmpty(s string) (string, error) {
+func ParseNonEmpty(env environment.Environment, s string) (string, error) {
 	if s == "" {
 		return "", errEmptyString
 	}
@@ -48,7 +49,7 @@ func ParseNonEmpty(s string) (string, error) {
 var regexpDomain = regexp.MustCompile(`^([a-zA-Z0-9][-a-zA-Z0-9]*\.)*[a-zA-Z0-9][-a-zA-Z0-9]*$`) // TODO: Make this regexp nicer!
 
 // ParseValidDomain checks that s is a valid domain and returns it in lowercase
-func ParseValidDomain(s string) (string, error) {
+func ParseValidDomain(env environment.Environment, s string) (string, error) {
 	if !regexpDomain.MatchString(s) {
 		return "", errors.Errorf("%q is not a valid domain", s)
 	}
@@ -56,7 +57,7 @@ func ParseValidDomain(s string) (string, error) {
 }
 
 // ParseValidDomains checks that s is a comma-seperated list of valid domains and returns them in lower case
-func ParseValidDomains(s string) ([]string, error) {
+func ParseValidDomains(env environment.Environment, s string) ([]string, error) {
 	if len(s) == 0 {
 		return []string{}, nil
 	}
@@ -70,13 +71,13 @@ func ParseValidDomains(s string) ([]string, error) {
 }
 
 // ParseNumber parses s as a decimal integer
-func ParseNumber(s string) (int, error) {
+func ParseNumber(env environment.Environment, s string) (int, error) {
 	value, err := strconv.ParseInt(s, 10, 64)
 	return int(value), err
 }
 
 // ParseHttpsURL parses a string into a url that starts with 'https://'
-func ParseHttpsURL(s string) (*url.URL, error) {
+func ParseHttpsURL(env environment.Environment, s string) (*url.URL, error) {
 	url, err := url.Parse(s)
 	if err != nil {
 		return nil, errors.Wrapf(err, "%q is not a valid URL", s)
@@ -90,7 +91,7 @@ func ParseHttpsURL(s string) (*url.URL, error) {
 var regexpEmail = regexp.MustCompile(`^([-a-zA-Z0-9]+)\@([a-zA-Z0-9][-a-zA-Z0-9]*\.)*[a-zA-Z0-9][-a-zA-Z0-9]*$`) // TODO: Make this regexp nicer!
 
 // ParseEmail checks that s represents an email, and then returns it as is.
-func ParseEmail(s string) (string, error) {
+func ParseEmail(env environment.Environment, s string) (string, error) {
 	if s == "" { // no email provided
 		return "", nil
 	}
@@ -103,7 +104,7 @@ func ParseEmail(s string) (string, error) {
 var regexpSlug = regexp.MustCompile(`^[a-zA-Z0-9][-a-zA-Z0-9]*$`) // TODO: Make this regexp nicer!
 
 // ParseSlug parses s as a slug and returns it as is.
-func ParseSlug(s string) (string, error) {
+func ParseSlug(env environment.Environment, s string) (string, error) {
 	if !regexpSlug.MatchString(s) {
 		return "", errors.Errorf("%q is not a valid slug", s)
 	}

pkg/targz/targz.go

@@ -6,17 +6,18 @@ import (
 	"compress/gzip"
 	"io"
 	"io/fs"
-	"os"
 	"path/filepath"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 )
 
 // Package packages the source directory into a 'tar.gz' file into destination.
 // If the destination already exists, it is truncated.
 //
 // onCopy, when not nil, is called for each file being copied into the archive.
-func Package(dst, src string, onCopy func(rel string, src string)) (count int64, err error) {
+func Package(env environment.Environment, dst, src string, onCopy func(rel string, src string)) (count int64, err error) {
 	// create the target archive
-	archive, err := os.Create(dst)
+	archive, err := env.Create(dst, environment.DefaultFilePerm)
 	if err != nil {
 		return 0, err
 	}
@@ -31,7 +32,7 @@ func Package(dst, src string, onCopy func(rel string, src string)) (count int64,
 	defer tarHandle.Close()
 
 	// and walk through it!
-	err = filepath.WalkDir(src, func(path string, entry fs.DirEntry, err error) error {
+	err = env.WalkDir(src, func(path string, entry fs.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}
@@ -74,7 +75,7 @@ func Package(dst, src string, onCopy func(rel string, src string)) (count int64,
 		}
 
 		// open the file
-		handle, err := os.Open(path)
+		handle, err := env.Open(path)
 		if err != nil {
 			return err
 		}

pkg/unpack/resource.go

@@ -3,9 +3,9 @@ package unpack
 import (
 	"io"
 	"io/fs"
-	"os"
 	"path/filepath"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"github.com/pkg/errors"
 )
 
@@ -16,9 +16,9 @@ var errExpectedDirectoryButGotFile = errors.New("expected a directory, but got a
 //
 // onInstallFile is called for each file or directory being installed.
 //
-// If the destination path does not exist, it is created using [os.MakeDirs]
+// If the destination path does not exist, it is created using [environment.MakeDirs]
 // The directory is installed recursively.
-func InstallDir(dst string, src string, fsys fs.FS, onInstallFile func(dst, src string)) error {
+func InstallDir(env environment.Environment, dst string, src string, fsys fs.FS, onInstallFile func(dst, src string)) error {
 	// open the source file
 	srcFile, err := fsys.Open(src)
 	if err != nil {
@@ -43,14 +43,14 @@ func InstallDir(dst string, src string, fsys fs.FS, onInstallFile func(dst, src
 
 	// do the installation of the directory.
 	// the type cast should be safe.
-	return installDir(dst, srcInfo, srcFile.(fs.ReadDirFile), src, fsys, onInstallFile)
+	return installDir(env, dst, srcInfo, srcFile.(fs.ReadDirFile), src, fsys, onInstallFile)
 }
 
 // installResource installs the resource at src within fsys to dst.
 //
 // OnInstallFile is called for each source and destination file.
 // OnInstallFile may be nil.
-func installResource(dst string, src string, fsys fs.FS, onInstallFile func(dst, src string)) error {
+func installResource(env environment.Environment, dst string, src string, fsys fs.FS, onInstallFile func(dst, src string)) error {
 	// open the srcFile
 	srcFile, err := fsys.Open(src)
 	if err != nil {
@@ -71,19 +71,19 @@ func installResource(dst string, src string, fsys fs.FS, onInstallFile func(dst,
 
 	// this is a directory, so the cast is safe!
 	if srcInfo.IsDir() {
-		return installDir(dst, srcInfo, srcFile.(fs.ReadDirFile), src, fsys, onInstallFile)
+		return installDir(env, dst, srcInfo, srcFile.(fs.ReadDirFile), src, fsys, onInstallFile)
 	}
 
 	// this is a regular file!
-	return installFile(dst, srcInfo, srcFile)
+	return installFile(env, dst, srcInfo, srcFile)
 }
 
-func installDir(dst string, srcInfo fs.FileInfo, srcFile fs.ReadDirFile, src string, fsys fs.FS, onInstallFile func(dst, src string)) error {
+func installDir(env environment.Environment, dst string, srcInfo fs.FileInfo, srcFile fs.ReadDirFile, src string, fsys fs.FS, onInstallFile func(dst, src string)) error {
 	// create the destination
-	dstStat, dstErr := os.Stat(dst)
+	dstStat, dstErr := env.Stat(dst)
 	switch {
-	case os.IsNotExist(dstErr):
+	case environment.IsNotExist(dstErr):
-		if err := os.MkdirAll(dst, srcInfo.Mode()); err != nil {
+		if err := env.MkdirAll(dst, srcInfo.Mode()); err != nil {
 			return errors.Wrapf(err, "Error creating destination directory %s", dst)
 		}
 	case dstErr != nil:
@@ -105,6 +105,7 @@ func installDir(dst string, srcInfo fs.FileInfo, srcFile fs.ReadDirFile, src str
 	// iterate over all the children
 	for _, entry := range entries {
 		if err := installResource(
+			env,
 			filepath.Join(dst, entry.Name()),
 			filepath.Join(src, entry.Name()),
 			fsys,
@@ -117,9 +118,9 @@ func installDir(dst string, srcInfo fs.FileInfo, srcFile fs.ReadDirFile, src str
 	return nil
 }
 
-func installFile(dst string, srcInfo fs.FileInfo, src fs.File) error {
+func installFile(env environment.Environment, dst string, srcInfo fs.FileInfo, src fs.File) error {
 	// create the file using the right mode!
-	file, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, srcInfo.Mode())
+	file, err := env.Create(dst, srcInfo.Mode())
 	if err != nil {
 		return err
 	}

pkg/unpack/template.go

@@ -6,9 +6,9 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"os"
 	"strings"
 
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
 	"golang.org/x/exp/maps"
 	"golang.org/x/exp/slices"
 )
@@ -201,7 +201,7 @@ parseloop:
 // Any existing file is truncated and overwritten.
 //
 // See [WriteTemplate] for possible errors.
-func InstallTemplate(dst string, context map[string]string, src string, fsys fs.FS) error {
+func InstallTemplate(env environment.Environment, dst string, context map[string]string, src string, fsys fs.FS) error {
 
 	// open the srcFile
 	srcFile, err := fsys.Open(src)
@@ -222,7 +222,7 @@ func InstallTemplate(dst string, context map[string]string, src string, fsys fs.
 	}
 
 	// open the destination file
-	file, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, srcInfo.Mode())
+	file, err := env.Create(dst, srcInfo.Mode())
 	if err != nil {
 		return err
 	}

program.go

@@ -41,7 +41,7 @@ func NewProgram() Program {
 
 			// when not running inside docker and we need a distillery
 			// then we should warn if we are not using the distillery executable.
-			if dis := context.Environment; !context.Args.Flags.InternalInDocker && context.Description.Requirements.NeedsDistillery && !dis.Config.UsingDistilleryExecutable() {
+			if dis := context.Environment; !context.Args.Flags.InternalInDocker && context.Description.Requirements.NeedsDistillery && !dis.Config.UsingDistilleryExecutable(dis.Environment) {
 				context.EPrintf(warnNoDeployWdcli, core.Executable, dis.Config.ExecutablePath())
 			}