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// Package zfsutil wraps the zfs(8)/jail(8) CLI operations Skiff relies on as
// its only state store - no separate app-metadata database.
package zfsutil
import (
"context"
"fmt"
"io"
"strings"
"skiff/internal/sh"
)
func snapRef(dataset, tag string) string {
return fmt.Sprintf("%s@%s", dataset, tag)
}
// Clone creates a new dataset from a (read-only) snapshot of base, mounted
// at mountpoint. base must already have a snapshot named baseSnapshot.
func Clone(ctx context.Context, out io.Writer, base, baseSnapshot, dataset, mountpoint string) error {
return sh.Run(ctx, out, "", "zfs", "clone", "-o", "mountpoint="+mountpoint, snapRef(base, baseSnapshot), dataset)
}
func Snapshot(ctx context.Context, out io.Writer, dataset, tag string) error {
return sh.Run(ctx, out, "", "zfs", "snapshot", snapRef(dataset, tag))
}
// Rollback discards everything written to dataset since the snapshot named
// tag, including any newer snapshots. This is Skiff's entire undo mechanism:
// used both for the automatic post-health-check-failure rollback and for a
// manual `skiff rollback` days later.
func Rollback(ctx context.Context, out io.Writer, dataset, tag string) error {
return sh.Run(ctx, out, "", "zfs", "rollback", "-r", snapRef(dataset, tag))
}
// DestroySnapshot removes a snapshot that was never needed as a rollback
// target - e.g. one taken right before an apply step that failed before
// anything actually changed. Left behind, it collides with the same tag on
// the next retry.
func DestroySnapshot(ctx context.Context, out io.Writer, dataset, tag string) error {
return sh.Run(ctx, out, "", "zfs", "destroy", snapRef(dataset, tag))
}
// Create makes a new, empty dataset mounted at mountpoint - unlike Clone,
// it has no origin snapshot to inherit from.
func Create(ctx context.Context, out io.Writer, dataset, mountpoint string) error {
return sh.Run(ctx, out, "", "zfs", "create", "-o", "mountpoint="+mountpoint, dataset)
}
// Rename renames a dataset. It deliberately does not touch the dataset's
// mountpoint property, which zfs(8) leaves unchanged on a rename - callers
// that care where the renamed dataset mounts must call SetMountpoint too.
func Rename(ctx context.Context, out io.Writer, oldName, newName string) error {
return sh.Run(ctx, out, "", "zfs", "rename", oldName, newName)
}
func SetMountpoint(ctx context.Context, out io.Writer, dataset, mountpoint string) error {
return sh.Run(ctx, out, "", "zfs", "set", "mountpoint="+mountpoint, dataset)
}
func Mount(ctx context.Context, out io.Writer, dataset string) error {
return sh.Run(ctx, out, "", "zfs", "mount", dataset)
}
func Unmount(ctx context.Context, out io.Writer, dataset string) error {
return sh.Run(ctx, out, "", "zfs", "unmount", dataset)
}
// Destroy removes an entire dataset and any snapshots on it, as opposed to
// DestroySnapshot's single dataset@tag. Recursive because callers use this
// to discard a whole discarded OS-layer clone - an operator's own manual
// snapshot on it shouldn't be able to block that.
func Destroy(ctx context.Context, out io.Writer, dataset string) error {
return sh.Run(ctx, out, "", "zfs", "destroy", "-r", dataset)
}
// Snapshots lists snapshot names (without the dataset@ prefix), newest last.
func Snapshots(ctx context.Context, dataset string) ([]string, error) {
raw, err := sh.Output(ctx, "", "zfs", "list", "-H", "-t", "snapshot", "-o", "name", "-s", "creation", "-r", dataset)
if err != nil {
return nil, err
}
var names []string
for _, line := range strings.Split(strings.TrimSpace(raw), "\n") {
if line == "" {
continue
}
parts := strings.SplitN(line, "@", 2)
if len(parts) == 2 {
names = append(names, parts[1])
}
}
return names, nil
}
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