volume prune: add dry-run support

cmd/podman/volumes/prune.go

@@ -45,6 +45,7 @@ func init() {
 	_ = pruneCommand.RegisterFlagCompletionFunc(filterFlagName, common.AutocompleteVolumePruneFilters)
 	flags.BoolP("force", "f", false, "Do not prompt for confirmation")
 	flags.BoolP("all", "a", false, "Remove all unused volumes, both anonymous and named")
+	flags.Bool("dry-run", false, "Show what would be pruned without actually pruning")
 }
 
 func prune(cmd *cobra.Command, _ []string) error {
@@ -74,7 +75,13 @@ func prune(cmd *cobra.Command, _ []string) error {
 		pruneOptions.Filters.Set("all", "true")
 	}
 
-	if !force {
+	dryRun, _ := cmd.Flags().GetBool("dry-run")
+	if force && dryRun {
+		return errors.New("--force and --dry-run cannot be used together")
+	}
+	pruneOptions.DryRun = dryRun
+
+	if !force && !dryRun {
 		reader := bufio.NewReader(os.Stdin)
 		if allFlag {
 			fmt.Println("WARNING! This will remove all volumes not used by at least one container. The following volumes will be removed:")
@@ -135,6 +142,9 @@ func prune(cmd *cobra.Command, _ []string) error {
 	if err != nil {
 		return err
 	}
+	if dryRun {
+		fmt.Println("Volumes that would be pruned:")
+	}
 	return utils.PrintVolumePruneResults(responses, false)
 }
 

docs/source/markdown/podman-volume-prune.1.md

@@ -21,6 +21,10 @@ removal unless **--force** is used.
 
 Remove all unused volumes (anonymous and named). Without this option, only anonymous unused volumes are removed.
 
+#### **--dry-run**
+
+Show which volumes would be pruned without removing them.
+
 #### **--filter**
 
 Provide filter values.
@@ -98,6 +102,12 @@ Prune unused volumes that do NOT have a specific label key:
 $ podman volume prune --filter label!=environment
 ```
 
+Preview all unused volumes without removing them.
+
+```
+$ podman volume prune --all --dry-run
+```
+
 ## SEE ALSO
 **[podman(1)](podman.1.md)**, **[podman-volume(1)](podman-volume.1.md)**
 

libpod/runtime_volume.go

@@ -111,31 +111,44 @@ func (r *Runtime) GetAllVolumes() ([]*Volume, error) {
 }
 
 // PruneVolumes removes unused volumes from the system
-func (r *Runtime) PruneVolumes(ctx context.Context, filterFuncs []VolumeFilter) ([]*reports.PruneReport, error) {
+func (r *Runtime) PruneVolumes(ctx context.Context, filterFuncs []VolumeFilter, dryRun bool) ([]*reports.PruneReport, error) {
 	preports := make([]*reports.PruneReport, 0)
 	vols, err := r.Volumes(filterFuncs...)
 	if err != nil {
 		return nil, err
 	}
 
 	for _, vol := range vols {
+		dangling, err := vol.IsDangling()
+		if err != nil {
+			preports = append(preports, &reports.PruneReport{
+				Id:  vol.Name(),
+				Err: err,
+			})
+		}
+		if !dangling {
+			continue
+		}
+
 		report := new(reports.PruneReport)
 		volSize, err := vol.Size()
 		if err != nil {
 			volSize = 0
 		}
 		report.Size = volSize
 		report.Id = vol.Name()
-		var timeout *uint
-		if err := r.RemoveVolume(ctx, vol, false, timeout); err != nil {
-			if !errors.Is(err, define.ErrVolumeBeingUsed) && !errors.Is(err, define.ErrVolumeRemoved) {
-				report.Err = err
+		if !dryRun {
+			var timeout *uint
+			if err := r.RemoveVolume(ctx, vol, false, timeout); err != nil {
+				if !errors.Is(err, define.ErrVolumeBeingUsed) && !errors.Is(err, define.ErrVolumeRemoved) {
+					report.Err = err
+				} else {
+					// We didn't remove the volume for some reason
+					continue
+				}
 			} else {
-				// We didn't remove the volume for some reason
-				continue
+				vol.newVolumeEvent(events.Prune)
 			}
-		} else {
-			vol.newVolumeEvent(events.Prune)
 		}
 		preports = append(preports, report)
 	}

pkg/api/handlers/compat/volumes.go

@@ -298,7 +298,7 @@ func PruneVolumes(w http.ResponseWriter, r *http.Request) {
 		filterFuncs = append(filterFuncs, filterFunc)
 	}
 
-	pruned, err := runtime.PruneVolumes(r.Context(), filterFuncs)
+	pruned, err := runtime.PruneVolumes(r.Context(), filterFuncs, false)
 	if err != nil {
 		utils.InternalServerError(w, err)
 		return

pkg/api/handlers/libpod/volumes.go

@@ -146,7 +146,16 @@ func PruneVolumes(w http.ResponseWriter, r *http.Request) {
 }
 
 func pruneVolumesHelper(r *http.Request) ([]*reports.PruneReport, error) {
+	decoder := r.Context().Value(api.DecoderKey).(*schema.Decoder)
 	runtime := r.Context().Value(api.RuntimeKey).(*libpod.Runtime)
+
+	query := struct {
+		DryRun bool `schema:"dryrun"`
+	}{}
+
+	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
+		return nil, err
+	}
 	filterMap, err := util.PrepareFilters(r)
 	if err != nil {
 		return nil, err
@@ -162,7 +171,7 @@ func pruneVolumesHelper(r *http.Request) ([]*reports.PruneReport, error) {
 		filterFuncs = append(filterFuncs, filterFunc)
 	}
 
-	reports, err := runtime.PruneVolumes(r.Context(), filterFuncs)
+	reports, err := runtime.PruneVolumes(r.Context(), filterFuncs, query.DryRun)
 	if err != nil {
 		return nil, err
 	}

pkg/api/server/register_volumes.go

@@ -95,6 +95,12 @@ func (s *APIServer) registerVolumeHandlers(r *mux.Router) error {
 	//        - `anonymous` When true/false, restrict to anonymous or named volumes only.
 	//        - `until=<timestamp>` Prune volumes created before this timestamp. The `<timestamp>` can be Unix timestamps, date formatted timestamps, or Go duration strings (e.g. `10m`, `1h30m`) computed relative to the daemon machine’s time.
 	//        - `label` (`label=<key>`, `label=<key>=<value>`, `label!=<key>`, or `label!=<key>=<value>`) Prune volumes with (or without, in case `label!=...` is used) the specified labels.
+	//  - in: query
+	//    name: dryrun
+	//    type: boolean
+	//    required: false
+	//    default: false
+	//    description: Show which volumes would be pruned without removing them.
 	// responses:
 	//   '200':
 	//      "$ref": "#/responses/volumePruneLibpod"

pkg/bindings/test/volumes_test.go

@@ -226,4 +226,20 @@ var _ = Describe("Podman volumes", func() {
 		Expect(err).ToNot(HaveOccurred())
 		Expect(pruned).To(HaveLen(1))
 	})
+
+	It("prune volume with dry-run", func() {
+		vol, err := volumes.Create(connText, entities.VolumeCreateOptions{Name: "vol"}, nil)
+		Expect(err).ToNot(HaveOccurred())
+
+		options := new(volumes.PruneOptions).
+			WithFilters(map[string][]string{"all": {"true"}}).
+			WithDryRun(true)
+
+		vols, err := volumes.Prune(connText, options)
+		Expect(err).ToNot(HaveOccurred())
+		Expect(reports.PruneReportsIds(vols)).To(ContainElement(vol.Name))
+
+		_, err = volumes.Inspect(connText, vol.Name, nil)
+		Expect(err).ToNot(HaveOccurred())
+	})
 })

pkg/bindings/volumes/types.go

@@ -24,6 +24,8 @@ type ListOptions struct {
 type PruneOptions struct {
 	// Filters applied to the pruning of volumes
 	Filters map[string][]string
+	// DryRun lists volumes that would be pruned without removing them.
+	DryRun *bool
 }
 
 // RemoveOptions are optional options for removing volumes

pkg/domain/entities/volumes.go

@@ -29,6 +29,7 @@ type VolumeInspectReport = types.VolumeInspectReport
 // - when filter "all" is true, all unused volumes are pruned.
 type VolumePruneOptions struct {
 	Filters url.Values `json:"filters" schema:"filters"`
+	DryRun  bool       `json:"dry_run" schema:"dryrun"`
 }
 
 type VolumeListOptions struct {

pkg/domain/infra/abi/volumes.go

@@ -144,11 +144,11 @@ func (ic *ContainerEngine) VolumePrune(ctx context.Context, options entities.Vol
 		}
 		funcs = append(funcs, filterFunc)
 	}
-	return ic.pruneVolumesHelper(ctx, funcs)
+	return ic.pruneVolumesHelper(ctx, funcs, options.DryRun)
 }
 
-func (ic *ContainerEngine) pruneVolumesHelper(ctx context.Context, filterFuncs []libpod.VolumeFilter) ([]*reports.PruneReport, error) {
-	pruned, err := ic.Libpod.PruneVolumes(ctx, filterFuncs)
+func (ic *ContainerEngine) pruneVolumesHelper(ctx context.Context, filterFuncs []libpod.VolumeFilter, dryRun bool) ([]*reports.PruneReport, error) {
+	pruned, err := ic.Libpod.PruneVolumes(ctx, filterFuncs, dryRun)
 	if err != nil {
 		return nil, err
 	}

pkg/domain/infra/tunnel/volumes.go

@@ -76,7 +76,7 @@ func (ic *ContainerEngine) VolumeInspect(_ context.Context, namesOrIds []string,
 }
 
 func (ic *ContainerEngine) VolumePrune(_ context.Context, opts entities.VolumePruneOptions) ([]*reports.PruneReport, error) {
-	options := new(volumes.PruneOptions).WithFilters(opts.Filters)
+	options := new(volumes.PruneOptions).WithFilters(opts.Filters).WithDryRun(opts.DryRun)
 	return volumes.Prune(ic.ClientCtx, options)
 }
 

test/e2e/volume_prune_test.go

@@ -5,6 +5,7 @@ package integration
 import (
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
+	. "go.podman.io/podman/v6/test/utils"
 )
 
 var _ = Describe("Podman volume prune", func() {
@@ -139,4 +140,80 @@ var _ = Describe("Podman volume prune", func() {
 		Expect(session.OutputToStringArray()).To(HaveLen(1))
 		Expect(session.OutputToStringArray()[0]).To(Equal(vol1))
 	})
+
+	It("podman volume prune --all --dry-run", func() {
+		vol1 := "vol1"
+		vol2 := "vol2"
+
+		podmanTest.PodmanExitCleanly("volume", "create", vol1)
+		podmanTest.PodmanExitCleanly("volume", "create", vol2)
+
+		session := podmanTest.PodmanExitCleanly("volume", "prune", "--all", "--dry-run")
+		Expect(session.OutputToString()).To(ContainSubstring("Volumes that would be pruned:"))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).To(ContainSubstring(vol2))
+
+		session = podmanTest.PodmanExitCleanly("volume", "ls", "-q")
+		Expect(session.OutputToStringArray()).To(HaveLen(2))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).To(ContainSubstring(vol2))
+	})
+
+	It("podman volume prune --filter --dry-run", func() {
+		vol1 := "vol1"
+		vol2 := "vol2"
+
+		podmanTest.PodmanExitCleanly("volume", "create", "--label", "dryrun=true", vol1)
+		podmanTest.PodmanExitCleanly("volume", "create", "--label", "dryrun=false", vol2)
+
+		session := podmanTest.PodmanExitCleanly("volume", "prune", "--dry-run", "--filter", "label=dryrun=true")
+		Expect(session.OutputToString()).To(ContainSubstring("Volumes that would be pruned:"))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).ToNot(ContainSubstring(vol2))
+
+		session = podmanTest.PodmanExitCleanly("volume", "ls", "-q")
+		Expect(session.OutputToStringArray()).To(HaveLen(2))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).To(ContainSubstring(vol2))
+	})
+
+	It("podman volume prune --dry-run only shows anonymous volumes", func() {
+		vol1 := "vol1"
+		anon_vol := podmanTest.PodmanExitCleanly("volume", "create").OutputToString()
+		podmanTest.PodmanExitCleanly("volume", "create", vol1)
+
+		session := podmanTest.PodmanExitCleanly("volume", "prune", "--dry-run")
+		Expect(session.OutputToString()).To(ContainSubstring("Volumes that would be pruned:"))
+		Expect(session.OutputToString()).To(ContainSubstring(anon_vol))
+
+		session = podmanTest.PodmanExitCleanly("volume", "ls", "-q")
+		Expect(session.OutputToStringArray()).To(HaveLen(2))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).To(ContainSubstring(anon_vol))
+	})
+
+	It("podman volume prune --all --dry-run excludes volumes in use", func() {
+		vol1 := "vol1"
+		vol2 := "vol2"
+
+		podmanTest.PodmanExitCleanly("volume", "create", vol1)
+		podmanTest.PodmanExitCleanly("volume", "create", vol2)
+		podmanTest.PodmanExitCleanly("create", "-v", "vol2:/data", ALPINE, "ls")
+
+		session := podmanTest.PodmanExitCleanly("volume", "prune", "--all", "--dry-run")
+		Expect(session.OutputToString()).To(ContainSubstring("Volumes that would be pruned:"))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).ToNot(ContainSubstring(vol2))
+
+		session = podmanTest.PodmanExitCleanly("volume", "ls", "-q")
+		Expect(session.OutputToStringArray()).To(HaveLen(2))
+		Expect(session.OutputToString()).To(ContainSubstring(vol1))
+		Expect(session.OutputToString()).To(ContainSubstring(vol2))
+	})
+
+	It("podman volume prune --force --dry-run fails", func() {
+		session := podmanTest.Podman([]string{"volume", "prune", "--force", "--dry-run"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(ExitWithError(125, "--force and --dry-run cannot be used together"))
+	})
 })