implement automatic snapshotting feature

cmd/autosnap.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"github.com/zrepl/zrepl/zfs"
+	"time"
+)
+
+type AutosnapContext struct {
+	Autosnap Autosnap
+}
+
+func doAutosnap(ctx AutosnapContext, log Logger) (err error) {
+
+	snap := ctx.Autosnap
+
+	filesystems, err := zfs.ZFSListMapping(snap.DatasetFilter)
+	if err != nil {
+		return fmt.Errorf("cannot filter datasets: %s", err)
+	}
+
+	suffix := time.Now().In(time.UTC).Format("20060102_150405_000")
+	snapname := fmt.Sprintf("%s%s", snap.Prefix, suffix)
+
+	hadError := false
+
+	for _, fs := range filesystems { // optimization: use recursive snapshots / channel programs here
+		log.Printf("snapshotting filesystem %s@%s", fs, snapname)
+		err := zfs.ZFSSnapshot(fs, snapname, false)
+		if err != nil {
+			log.Printf("error snapshotting %s: %s", fs, err)
+			hadError = true
+		}
+	}
+
+	if hadError {
+		err = fmt.Errorf("errors occurred during autosnap, check logs for details")
+	}
+
+	return
+
+}