wdcli: Implement backup & snapshot

This commit implements command backup and snapshot.

env/backup.go

@@ -0,0 +1,189 @@
+package env
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/fsx"
+	"github.com/FAU-CDI/wisski-distillery/internal/logging"
+	"github.com/pkg/errors"
+	"github.com/tkw1536/goprogram/stream"
+)
+
+// backupDescription is a description for a backup
+type BackupDescription struct {
+	Dest string // destination path
+}
+
+// Snapshot represents the result of generating a snapshot
+type Backup struct {
+	Description BackupDescription
+
+	// various error states, which are ignored when creating the snapshot
+	ErrPanic interface{}
+
+	SQLErr error
+	TSErr  error
+
+	ConfigFileErr       error
+	ConfigFilesManifest map[string]error
+
+	InstanceListErr   error
+	InstancesManifest []Snapshot
+}
+
+func (dis *Distillery) Backup(io stream.IOStream, description BackupDescription) (backup Backup) {
+	backup.Description = description
+
+	// catch anything critical that happened during the snapshot
+	defer func() {
+		backup.ErrPanic = recover()
+	}()
+
+	backup.run(io, dis)
+	return
+}
+
+var errBackupSkipFile = errors.New("<file not found>")
+
+func (backup *Backup) run(io stream.IOStream, dis *Distillery) {
+	// create a wait group, and message channel
+	wg := &sync.WaitGroup{}
+	messages := make(chan string, 4)
+
+	// backup the sql
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		sqlPath := filepath.Join(backup.Description.Dest, "sql.sql")
+		messages <- sqlPath
+
+		sql, err := os.Create(sqlPath)
+		if err != nil {
+			backup.SQLErr = err
+			return
+		}
+		defer sql.Close()
+
+		// directly store the result
+		backup.SQLErr = dis.SQL().BackupAll(io, sql)
+	}()
+
+	// backup the triplestore
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		tsPath := filepath.Join(backup.Description.Dest, "triplestore")
+		messages <- tsPath
+
+		// directly store the result
+		backup.TSErr = dis.Triplestore().BackupAll(tsPath)
+	}()
+
+	// backup configuration files
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		cfgBackupDir := filepath.Join(backup.Description.Dest, "config")
+		if err := os.Mkdir(cfgBackupDir, fs.ModeDir); err != nil {
+			backup.ConfigFileErr = err
+			return
+		}
+
+		files := []string{
+			filepath.Join(dis.Config.DeployRoot, ".env"),  // TODO: put the name of the configuration file somewhere
+			filepath.Join(dis.Config.DeployRoot, "wdcli"), // TODO: constant the name of the executable
+			dis.Config.SelfOverridesFile,
+			dis.Config.GlobalAuthorizedKeysFile,
+		}
+
+		backup.ConfigFilesManifest = make(map[string]error, len(files))
+		for _, src := range files {
+			if !fsx.IsFile(src) {
+				backup.ConfigFilesManifest[src] = errBackupSkipFile
+				continue
+			}
+			dest := filepath.Join(cfgBackupDir, filepath.Base(src))
+
+			// copy the config file and store the error message
+			messages <- src
+			backup.ConfigFilesManifest[src] = fsx.CopyFile(dest, src)
+		}
+	}()
+
+	// backup instances
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		instancesBackupDir := filepath.Join(backup.Description.Dest, "instances")
+		if err := os.Mkdir(instancesBackupDir, fs.ModeDir); err != nil {
+			backup.InstanceListErr = err
+			return
+		}
+
+		// list all instances
+		instances, err := dis.AllInstances()
+		if err != nil {
+			backup.InstanceListErr = err
+			return
+		}
+
+		iochild := stream.NewIOStream(io.Stderr, io.Stderr, nil, 0)
+
+		backup.InstancesManifest = make([]Snapshot, len(instances))
+		for i, instance := range instances {
+			backup.InstancesManifest[i] = func() Snapshot {
+				dir := filepath.Join(instancesBackupDir, instance.Slug)
+				if err := os.Mkdir(dir, fs.ModeDir); err != nil {
+					return Snapshot{
+						ErrPanic: err,
+					}
+				}
+
+				messages <- dir
+				return instance.Snapshot(iochild, SnapshotDescription{
+					Dest: dir,
+				})
+			}()
+		}
+
+	}()
+
+	// wait for the group, then close the message channel.
+	go func() {
+		wg.Wait()
+		close(messages)
+	}()
+
+	// print out all the messages
+	for message := range messages {
+		io.Println(message)
+	}
+}
+
+// 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 {
+	return logging.LogOperation(func() error {
+		reportPath := filepath.Join(backup.Description.Dest, "report.txt")
+		io.Println(reportPath)
+
+		// create the report file!
+		report, err := os.Create(reportPath)
+		if err != nil {
+			return err
+		}
+		defer report.Close()
+
+		// print the report into it!
+		_, err = fmt.Fprintf(report, "%#v\n", backup)
+		return err
+	}, io, "Writing backup report")
+}