Add docker_volumes_remove_anonymous: remove leftover unmounted anonymous volumes (issue 1796)

modules/docker/cmd/docker-tools/docker.go

@@ -1215,3 +1215,67 @@ func (c *Client) DaemonConfig(ctx context.Context) (map[string]any, error) {
 	answer["note"] = "keys read only at start take effect at the daemon's next restart; with live-restore on, a restart keeps every container running"
 	return answer, nil
 }
+
+// RemoveVolumesAsk is what docker_volumes_remove_anonymous is asked to take.
+type RemoveVolumesAsk struct {
+	DryRun        bool
+	Why           string
+	CreatedBefore *time.Time
+}
+
+// RemoveAnonymousVolumes removes the leftover anonymous volumes (novox/hq issue 1796): those docker
+// labels anonymous, which no container mounts in any state, so none a mesh-held container holds. The
+// classification is Volumes' own, not a copy. Every other volume is answered with why it stays. Each
+// is removed by its own `docker volume rm`, never forced and never `volume prune`, so one the daemon
+// refuses is reported and the rest still go.
+func (c *Client) RemoveAnonymousVolumes(ctx context.Context, a RemoveVolumesAsk) (map[string]any, error) {
+	if !a.DryRun && strings.TrimSpace(a.Why) == "" {
+		return nil, fmt.Errorf("why is required when dry_run is false")
+	}
+	all, err := c.Volumes(ctx, false, false)
+	if err != nil {
+		return nil, err
+	}
+	candidates := []string{}
+	skipped := []map[string]any{}
+	skip := func(name, why string) { skipped = append(skipped, map[string]any{"name": name, "why": why}) }
+	for _, v := range all["volumes"].([]map[string]any) {
+		name := fmt.Sprint(v["name"])
+		switch by := v["mounted_by"].([]map[string]any); {
+		case v["anonymous"] != true:
+			skip(name, "not anonymous: a named volume is data")
+		case v["mesh_held"] == true:
+			skip(name, "mounted by a container the mesh holds")
+		case len(by) > 0:
+			skip(name, fmt.Sprintf("mounted by %v (%v)", by[0]["container"], by[0]["state"]))
+		case a.CreatedBefore != nil && !volumeOlder(fmt.Sprint(v["created"]), *a.CreatedBefore):
+			skip(name, "not created before "+a.CreatedBefore.Format(time.RFC3339)+" (created "+fmt.Sprint(v["created"])+")")
+		default:
+			candidates = append(candidates, name)
+		}
+	}
+	answer := map[string]any{"dry_run": a.DryRun, "skipped": skipped,
+		"space_freed": "not reported: docker volume rm names what it removed; docker_disk_usage shows the space"}
+	if a.DryRun {
+		answer["would_remove"] = candidates
+		answer["note"] = "nothing was removed: call again with dry_run false and why to remove them"
+		return answer, nil
+	}
+	removed := []string{}
+	for _, name := range candidates {
+		if _, err := c.docker(ctx, "volume", "rm", name); err != nil {
+			skip(name, "docker refused: "+err.Error())
+			continue
+		}
+		removed = append(removed, name)
+	}
+	answer["skipped"] = skipped
+	answer["removed"], answer["count"], answer["why"] = removed, len(removed), a.Why
+	return answer, nil
+}
+
+// volumeOlder is whether a volume's CreatedAt is before the cutoff; one that cannot be read is not.
+func volumeOlder(created string, cutoff time.Time) bool {
+	t, err := time.Parse(time.RFC3339Nano, created)
+	return err == nil && t.Before(cutoff)
+}