TODO.md

@@ -22,6 +22,17 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
+- 2026-10-07: Made per-name retention work when the hostname contains `_`
+  ([issue #230](https://git.eeqj.de/sneak/vaultik/issues/230)). A
+  snapshot ID is `hostname_name_timestamp`, and the name was read as
+  everything between the first and the last `_`, so with
+  `hostname: my_host` the name `home` came out as `host_home`.
+  `snapshot purge --keep-latest --snapshot home` then printed "No
+  snapshots to delete", and `snapshot create --prune` purged nothing
+  without a message. The name is now read using the hostname the
+  `snapshots` table stores with each snapshot, cut at its first `.` as it
+  is in the ID.
+
 - 2026-10-07: Made `remote info` stop reporting a snapshot's blobs as
   orphaned when its manifest cannot be read, and stop printing raw
   names from under `metadata/`

internal/snapshot/snapshot.go

@@ -105,17 +105,21 @@ func (sm *SnapshotManager) CreateSnapshot(
 	return sm.CreateSnapshotWithName(ctx, hostname, "", version, gitRevision)
 }
 
+// ShortHostname returns hostname up to its first dot. A snapshot ID starts
+// with this form, while the snapshots table stores the full hostname.
+func ShortHostname(hostname string) string {
+	short, _, _ := strings.Cut(hostname, ".")
+
+	return short
+}
+
 // CreateSnapshotWithName creates a new snapshot record with an optional
 // snapshot name. The snapshot ID format is: hostname_name_timestamp or
 // hostname_timestamp if name is empty.
 func (sm *SnapshotManager) CreateSnapshotWithName(
 	ctx context.Context, hostname, name, version, gitRevision string,
 ) (string, error) {
-	// Use short hostname (strip domain if present)
-	shortHostname := hostname
-	if before, _, ok := strings.Cut(hostname, "."); ok {
-		shortHostname = before
-	}
+	shortHostname := ShortHostname(hostname)
 
 	// Build snapshot ID with optional name
 	timestamp := time.Now().UTC().Format("2006-01-02T15:04:05Z")

internal/vaultik/helpers.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/dustin/go-humanize"
+	"sneak.berlin/go/vaultik/internal/snapshot"
 	"sneak.berlin/go/vaultik/internal/types"
 )
 
@@ -46,12 +47,9 @@ const (
 	year  = 365 * day
 )
 
-// Snapshot IDs split on "_" into hostname, optional name parts, and a
-// trailing timestamp.
-const (
-	minSnapshotIDParts     = 2
-	minSnapshotIDNameParts = 3
-)
+// A snapshot ID split on "_" has at least a hostname and a trailing
+// timestamp.
+const minSnapshotIDParts = 2
 
 // SnapshotInfo contains information about a snapshot.
 //
@@ -121,20 +119,27 @@ func parseSnapshotTimestamp(snapshotID string) (time.Time, error) {
 	return timestamp.UTC(), nil
 }
 
-// parseSnapshotName extracts the snapshot name from a snapshot ID.
-// Format: hostname_snapshotname_timestamp — the middle part(s) between hostname
-// and the RFC3339 timestamp are the snapshot name (may contain underscores).
-// Returns the snapshot name, or empty string if the ID is malformed.
-func parseSnapshotName(snapshotID string) string {
-	parts := strings.Split(snapshotID, "_")
-	if len(parts) < minSnapshotIDNameParts {
-		// Format: hostname_timestamp — no snapshot name
+// parseSnapshotName extracts the snapshot name from a snapshot ID of the
+// form hostname_name_timestamp, given the hostname stored with that
+// snapshot. The hostname and the name may both contain underscores, so the
+// name is what is left after removing the short hostname and its "_" from
+// the front and the last "_" and the timestamp from the end. Returns "" for
+// an ID with no name (hostname_timestamp), and for an ID that does not start
+// with that hostname, which CreateSnapshotWithName never writes.
+func parseSnapshotName(snapshotID, hostname string) string {
+	prefix := snapshot.ShortHostname(hostname) + "_"
+
+	rest, ok := strings.CutPrefix(snapshotID, prefix)
+	if !ok {
 		return ""
 	}
-	// Format: hostname_name_timestamp — middle parts are the name.
-	// The last part is the RFC3339 timestamp, the first part is the hostname,
-	// everything in between is the snapshot name (which may itself contain underscores).
-	return strings.Join(parts[1:len(parts)-1], "_")
+
+	end := strings.LastIndex(rest, "_")
+	if end < 0 {
+		return ""
+	}
+
+	return rest[:end]
 }
 
 // parseDuration parses a duration string with support for human-friendly units:

internal/vaultik/helpers_test.go

@@ -11,33 +11,55 @@ func TestParseSnapshotName(t *testing.T) {
 	tests := []struct {
 		name       string
 		snapshotID string
+		hostname   string
 		want       string
 	}{
 		{
 			name:       "standard format with name",
 			snapshotID: "myhost_home_2026-01-12T14:41:15Z",
+			hostname:   "myhost",
 			want:       "home",
 		},
 		{
 			name:       "standard format with different name",
 			snapshotID: "server1_system_2026-02-15T09:30:00Z",
+			hostname:   "server1",
 			want:       "system",
 		},
 		{
 			name:       "name with underscores",
 			snapshotID: "myhost_my_special_backup_2026-03-01T00:00:00Z",
+			hostname:   "myhost",
 			want:       "my_special_backup",
 		},
+		{
+			name:       "hostname with underscores",
+			snapshotID: "my_host_docs_2026-03-01T00:00:00Z",
+			hostname:   "my_host",
+			want:       "docs",
+		},
+		{
+			name:       "stored hostname with domain",
+			snapshotID: "my_host_mail_2026-03-01T00:00:00Z",
+			hostname:   "my_host.example.com",
+			want:       "mail",
+		},
+		{
+			name:       "no name",
+			snapshotID: "my_host_2026-03-01T00:00:00Z",
+			hostname:   "my_host",
+			want:       "",
+		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			got := parseSnapshotName(tt.snapshotID)
+			got := parseSnapshotName(tt.snapshotID, tt.hostname)
 			if got != tt.want {
-				t.Errorf("parseSnapshotName(%q) = %q, want %q",
-					tt.snapshotID, got, tt.want)
+				t.Errorf("parseSnapshotName(%q, %q) = %q, want %q",
+					tt.snapshotID, tt.hostname, got, tt.want)
 			}
 		})
 	}

internal/vaultik/purge_local_remote_consistency_test.go

@@ -42,7 +42,7 @@ func setupConsistencyTest(
 		completedAt := startedAt.Add(5 * time.Minute)
 		snap := &database.Snapshot{
 			ID:             types.SnapshotID(id),
-			Hostname:       testHostname,
+			Hostname:       snapHostname,
 			VaultikVersion: testLabel,
 			StartedAt:      startedAt,
 			CompletedAt:    &completedAt,

internal/vaultik/purge_per_name_test.go

@@ -17,8 +17,10 @@ import (
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
 
-// Snapshot IDs reused across the purge tests.
+// Snapshot IDs reused across the purge tests, and the hostname they were
+// taken on.
 const (
+	snapHostname = "testhost"
 	snapSystemT0 = "testhost_system_2026-01-01T00:00:00Z"
 	snapHomeT0   = "testhost_home_2026-01-01T00:00:00Z"
 	snapHomeT1   = "testhost_home_2026-01-01T01:00:00Z"
@@ -26,9 +28,12 @@ const (
 )
 
 // setupPurgeTest creates a Vaultik instance with an in-memory database and mock
-// storage pre-populated with the given snapshot IDs. Each snapshot is marked as
-// completed. Remote metadata stubs are created so syncWithRemote keeps them.
-func setupPurgeTest(t *testing.T, snapshotIDs []string) *vaultik.Vaultik {
+// storage pre-populated with the given snapshot IDs, all taken on hostname.
+// Each snapshot is marked as completed. Remote metadata stubs are created so
+// syncWithRemote keeps them.
+func setupPurgeTest(
+	t *testing.T, hostname string, snapshotIDs []string,
+) *vaultik.Vaultik {
 	t.Helper()
 
 	ctx := context.Background()
@@ -51,7 +56,7 @@ func setupPurgeTest(t *testing.T, snapshotIDs []string) *vaultik.Vaultik {
 		completedAt := startedAt.Add(5 * time.Minute)
 		snap := &database.Snapshot{
 			ID:             types.SnapshotID(id),
-			Hostname:       "testhost",
+			Hostname:       types.Hostname(hostname),
 			VaultikVersion: testLabel,
 			StartedAt:      startedAt,
 			CompletedAt:    &completedAt,
@@ -120,7 +125,7 @@ func TestPurgeKeepLatest_PerName(t *testing.T) {
 		"testhost_system_2026-01-01T04:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -148,7 +153,7 @@ func TestPurgeKeepLatest_SingleName(t *testing.T) {
 		"testhost_home_2026-01-01T02:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -176,7 +181,7 @@ func TestPurgeKeepLatest_WithNameFilter(t *testing.T) {
 		"testhost_home_2026-01-01T04:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -198,7 +203,7 @@ func TestPurgeKeepLatest_NoSnapshots(t *testing.T) {
 	log.Initialize(log.Config{})
 	t.Parallel()
 
-	v := setupPurgeTest(t, nil)
+	v := setupPurgeTest(t, snapHostname, nil)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -216,7 +221,7 @@ func TestPurgeKeepLatest_NameFilterNoMatch(t *testing.T) {
 		"testhost_system_2026-01-01T01:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -243,7 +248,7 @@ func TestPurgeOlderThan_WithNameFilter(t *testing.T) {
 		snapHomeT0,
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	// Purge only "home" snapshots older than 365 days
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
@@ -277,7 +282,7 @@ func TestPurgeKeepLatest_ThreeNames(t *testing.T) {
 		"testhost_home_2026-01-01T06:00:00Z",
 	}
 
-	v := setupPurgeTest(t, snapshotIDs)
+	v := setupPurgeTest(t, snapHostname, snapshotIDs)
 
 	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
 		KeepLatest: true,
@@ -291,3 +296,28 @@ func TestPurgeKeepLatest_ThreeNames(t *testing.T) {
 	assert.Contains(t, remaining, "testhost_system_2026-01-01T04:00:00Z")
 	assert.Contains(t, remaining, "testhost_media_2026-01-01T05:00:00Z")
 }
+
+// A hostname may contain underscores, so the snapshot name cannot be found
+// by splitting the ID at them. A purge by name must still select "docs".
+func TestPurgeKeepLatest_HostnameWithUnderscore(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	const (
+		system = "my_host_system_2026-01-01T00:00:00Z"
+		docsT1 = "my_host_docs_2026-01-01T01:00:00Z"
+		docsT2 = "my_host_docs_2026-01-01T02:00:00Z"
+	)
+
+	v := setupPurgeTest(t, "my_host", []string{system, docsT1, docsT2})
+
+	err := v.PurgeSnapshotsWithOptions(&vaultik.SnapshotPurgeOptions{
+		KeepLatest: true,
+		Force:      true,
+		Names:      []string{"docs"},
+	})
+	require.NoError(t, err)
+
+	assert.ElementsMatch(t, []string{system, docsT2},
+		listRemainingSnapshots(t, v))
+}

internal/vaultik/snapshot.go

@@ -14,6 +14,7 @@ import (
 
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/snapshot"
+	"sneak.berlin/go/vaultik/internal/types"
 )
 
 // Sentinel errors for snapshot management.
@@ -495,19 +496,23 @@ func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
 		nameFilter[n] = struct{}{}
 	}
 
-	// Collect completed snapshots, applying the name filter.
+	// Collect completed snapshots and their names, applying the name filter.
 	snapshots := make([]SnapshotInfo, 0, len(dbSnapshots))
+	names := make(map[types.SnapshotID]string, len(dbSnapshots))
+
 	for _, s := range dbSnapshots {
 		if s.CompletedAt == nil {
 			continue
 		}
 
+		name := parseSnapshotName(s.ID.String(), s.Hostname.String())
 		if len(nameFilter) > 0 {
-			if _, ok := nameFilter[parseSnapshotName(s.ID.String())]; !ok {
+			if _, ok := nameFilter[name]; !ok {
 				continue
 			}
 		}
 
+		names[s.ID] = name
 		snapshots = append(snapshots, SnapshotInfo{
 			ID:             s.ID,
 			Timestamp:      s.StartedAt,
@@ -520,7 +525,7 @@ func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
 		return snapshots[i].Timestamp.After(snapshots[j].Timestamp)
 	})
 
-	toDelete, err := selectSnapshotsToPurge(snapshots, opts)
+	toDelete, err := selectSnapshotsToPurge(snapshots, names, opts)
 	if err != nil {
 		return err
 	}
@@ -538,9 +543,11 @@ func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
 
 // selectSnapshotsToPurge applies the purge retention criteria to the
 // newest-first sorted snapshot list and returns the deletion
-// candidates.
+// candidates. names maps each snapshot's ID to its snapshot name.
 func selectSnapshotsToPurge(
-	snapshots []SnapshotInfo, opts *SnapshotPurgeOptions,
+	snapshots []SnapshotInfo,
+	names map[types.SnapshotID]string,
+	opts *SnapshotPurgeOptions,
 ) ([]SnapshotInfo, error) {
 	var toDelete []SnapshotInfo
 
@@ -551,7 +558,7 @@ func selectSnapshotsToPurge(
 		seen := make(map[string]bool)
 
 		for _, snap := range snapshots {
-			name := parseSnapshotName(snap.ID.String())
+			name := names[snap.ID]
 			if seen[name] {
 				toDelete = append(toDelete, snap)