wdcli: Implement backup & snapshot

This commit implements command backup and snapshot.

cmd/backup.go

@@ -0,0 +1,116 @@
+package cmd
+
+import (
+	"io/fs"
+	"os"
+
+	wisski_distillery "github.com/FAU-CDI/wisski-distillery"
+	"github.com/FAU-CDI/wisski-distillery/env"
+	"github.com/FAU-CDI/wisski-distillery/internal/logging"
+	"github.com/FAU-CDI/wisski-distillery/internal/targz"
+	"github.com/tkw1536/goprogram/exit"
+)
+
+// Backup is the 'backup' command
+var Backup wisski_distillery.Command = backup{}
+
+type backup struct {
+	StagingOnly bool `short:"s" long:"staging-only" description:"Do not package into a backup archive, but only create a staging directory"`
+	Positionals struct {
+		Dest string `positional-arg-name:"DEST" description:"Destination path to write backup archive to. Defaults to the snapshots/archives/ directory"`
+	} `positional-args:"true"`
+}
+
+func (backup) Description() wisski_distillery.Description {
+	return wisski_distillery.Description{
+		Requirements: env.Requirements{
+			NeedsConfig: true,
+		},
+		Command:     "backup",
+		Description: "Makes a backup of the entire distillery",
+	}
+}
+
+var errBackupFailed = exit.Error{
+	Message:  "Failed to make a backup",
+	ExitCode: exit.ExitGeneric,
+}
+
+func (bk backup) Run(context wisski_distillery.Context) error {
+	dis := context.Environment
+	var err error
+
+	// determine the target path for the archive
+	var sPath string
+	if !bk.StagingOnly {
+		// regular mode: create a temporary staging directory
+		logging.LogMessage(context.IOStream, "Creating new snapshot staging directory")
+		sPath, err = dis.NewSnapshotStagingDir("")
+		if err != nil {
+			return errSnapshotFailed.Wrap(err)
+		}
+		defer func() {
+			logging.LogMessage(context.IOStream, "Removing snapshot staging directory")
+			os.RemoveAll(sPath)
+		}()
+	} else {
+		// staging mode: use dest as a destination
+		sPath = bk.Positionals.Dest
+		if sPath == "" {
+			sPath, err = dis.NewSnapshotStagingDir("")
+			if err != nil {
+				return errSnapshotFailed.Wrap(err)
+			}
+		}
+
+		// create the directory (if it doesn't already exist)
+		logging.LogMessage(context.IOStream, "Creating staging directory")
+		err = os.Mkdir(sPath, fs.ModePerm)
+		if !os.IsExist(err) && err != nil {
+			return errSnapshotFailed.WithMessageF(err)
+		}
+		err = nil
+	}
+	context.Println(sPath)
+
+	logging.LogOperation(func() error {
+		// take a snapshot into the staging area!
+		backup := dis.Backup(context.IOStream, env.BackupDescription{
+			Dest: sPath,
+		})
+
+		// write out the report, ignoring any errors!
+		backup.WriteReport(context.IOStream)
+
+		return nil
+	}, context.IOStream, "Generating Backup")
+
+	// if we requested to only have a staging area, then we are done
+	if bk.StagingOnly {
+		context.Printf("Wrote %s\n", sPath)
+		return nil
+	}
+
+	// create the archive path
+	archivePath := bk.Positionals.Dest
+	if archivePath == "" {
+		archivePath = dis.NewSnapshotArchivePath("")
+	}
+
+	// and write everything into it!
+	// TODO: Should we move the open call to here?
+	var count int64
+	if err := logging.LogOperation(func() error {
+		context.IOStream.Println(archivePath)
+
+		count, err = targz.Package(archivePath, sPath, func(dst, src string) {
+			context.Println(dst)
+		})
+		return err
+	}, context.IOStream, "Writing backup archive"); err != nil {
+		return errSnapshotFailed.Wrap(err)
+	}
+	context.Printf("Wrote %d byte(s) to %s\n", count, archivePath)
+
+	return nil
+}