Add podman system prune --external

This just calls GC on the local storage, which will remove any leftover
directories from previous containers that are not in the podman db anymore.
This is useful primarily for transient store mode, but can also help in
the case of an unclean shutdown.

Also adds some e2e test to ensure prune --external works.

Signed-off-by: Alexander Larsson <alexl@redhat.com>

cmd/podman/system/prune.go

@@ -47,6 +47,7 @@ func init() {
 	flags := pruneCommand.Flags()
 	flags.BoolVarP(&force, "force", "f", false, "Do not prompt for confirmation.  The default is false")
 	flags.BoolVarP(&pruneOptions.All, "all", "a", false, "Remove all unused data")
+	flags.BoolVar(&pruneOptions.External, "external", false, "Remove container data in storage not controlled by podman")
 	flags.BoolVar(&pruneOptions.Volume, "volumes", false, "Prune volumes")
 	filterFlagName := "filter"
 	flags.StringArrayVar(&filters, filterFlagName, []string{}, "Provide filter values (e.g. 'label=<key>=<value>')")
@@ -55,8 +56,8 @@ func init() {
 
 func prune(cmd *cobra.Command, args []string) error {
 	var err error
-	// Prompt for confirmation if --force is not set
-	if !force {
+	// Prompt for confirmation if --force is not set, unless --external
+	if !force && !pruneOptions.External {
 		reader := bufio.NewReader(os.Stdin)
 		volumeString := ""
 		if pruneOptions.Volume {
@@ -113,7 +114,9 @@ func prune(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	fmt.Printf("Total reclaimed space: %s\n", units.HumanSize((float64)(response.ReclaimedSpace)))
+	if !pruneOptions.External {
+		fmt.Printf("Total reclaimed space: %s\n", units.HumanSize((float64)(response.ReclaimedSpace)))
+	}
 	return nil
 }
 

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

@@ -18,6 +18,15 @@ By default, volumes are not removed to prevent important data from being deleted
 
 Recursively remove all unused pods, containers, images, networks, and volume data. (Maximum 50 iterations.)
 
+#### **--external**
+
+Removes all leftover container storage files from local storage that are not managed by podman. In normal circumstances no such data should exist, but in case of an unclean shutdown the podman database may be corrupted and cause his.
+
+However, when using transient storage mode, the podman database does not persist. This means containers can will leave the writable layers on disk after a reboot. If you use transient store
+it it recommended that you run **podman system prune --external** once some time after each boot.
+
+This option is incompatible with **--all** and **--filter** and drops the default behaviour of removing unused resources.
+
 #### **--filter**=*filters*
 
 Provide filter values.

libpod/runtime.go

@@ -959,6 +959,10 @@ func (r *Runtime) StorageConfig() storage.StoreOptions {
 	return r.storageConfig
 }
 
+func (r *Runtime) GarbageCollect() error {
+	return r.store.GarbageCollect()
+}
+
 // RunRoot retrieves the current c/storage temporary directory in use by Libpod.
 func (r *Runtime) RunRoot() string {
 	if r.store == nil {

pkg/api/handlers/libpod/system.go

@@ -19,8 +19,9 @@ func SystemPrune(w http.ResponseWriter, r *http.Request) {
 	runtime := r.Context().Value(api.RuntimeKey).(*libpod.Runtime)
 
 	query := struct {
-		All     bool `schema:"all"`
-		Volumes bool `schema:"volumes"`
+		All      bool `schema:"all"`
+		Volumes  bool `schema:"volumes"`
+		External bool `schema:"external"`
 	}{}
 
 	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
@@ -38,9 +39,10 @@ func SystemPrune(w http.ResponseWriter, r *http.Request) {
 	containerEngine := abi.ContainerEngine{Libpod: runtime}
 
 	pruneOptions := entities.SystemPruneOptions{
-		All:     query.All,
-		Volume:  query.Volumes,
-		Filters: *filterMap,
+		All:      query.All,
+		Volume:   query.Volumes,
+		Filters:  *filterMap,
+		External: query.External,
 	}
 	report, err := containerEngine.SystemPrune(r.Context(), pruneOptions)
 	if err != nil {

pkg/bindings/system/types.go

@@ -14,9 +14,10 @@ type EventsOptions struct {
 //
 //go:generate go run ../generator/generator.go PruneOptions
 type PruneOptions struct {
-	All     *bool
-	Filters map[string][]string
-	Volumes *bool
+	All      *bool
+	Filters  map[string][]string
+	Volumes  *bool
+	External *bool
 }
 
 // VersionOptions are optional options for getting version info

pkg/domain/entities/system.go

@@ -18,9 +18,10 @@ type ServiceOptions struct {
 
 // SystemPruneOptions provides options to prune system.
 type SystemPruneOptions struct {
-	All     bool
-	Volume  bool
-	Filters map[string][]string `json:"filters" schema:"filters"`
+	All      bool
+	Volume   bool
+	Filters  map[string][]string `json:"filters" schema:"filters"`
+	External bool
 }
 
 // SystemPruneReport provides report after system prune is executed.

pkg/domain/infra/abi/system.go

@@ -160,6 +160,18 @@ func (ic *ContainerEngine) SetupRootless(_ context.Context, noMoveProcess bool)
 // SystemPrune removes unused data from the system. Pruning pods, containers, networks, volumes and images.
 func (ic *ContainerEngine) SystemPrune(ctx context.Context, options entities.SystemPruneOptions) (*entities.SystemPruneReport, error) {
 	var systemPruneReport = new(entities.SystemPruneReport)
+
+	if options.External {
+		if options.All || options.Volume || len(options.Filters) > 0 {
+			return nil, fmt.Errorf("system prune --external cannot be combined with other options")
+		}
+		err := ic.Libpod.GarbageCollect()
+		if err != nil {
+			return nil, err
+		}
+		return systemPruneReport, nil
+	}
+
 	filters := []string{}
 	for k, v := range options.Filters {
 		filters = append(filters, fmt.Sprintf("%s=%s", k, v[0]))

pkg/domain/infra/tunnel/system.go

@@ -19,7 +19,7 @@ func (ic *ContainerEngine) SetupRootless(_ context.Context, noMoveProcess bool)
 
 // SystemPrune prunes unused data from the system.
 func (ic *ContainerEngine) SystemPrune(ctx context.Context, opts entities.SystemPruneOptions) (*entities.SystemPruneReport, error) {
-	options := new(system.PruneOptions).WithAll(opts.All).WithVolumes(opts.Volume).WithFilters(opts.Filters)
+	options := new(system.PruneOptions).WithAll(opts.All).WithVolumes(opts.Volume).WithFilters(opts.Filters).WithExternal(opts.External)
 	return system.Prune(ic.ClientCtx, options)
 }
 

test/e2e/prune_test.go

@@ -3,6 +3,7 @@ package integration
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 
 	. "github.com/containers/podman/v4/test/utils"
 	. "github.com/onsi/ginkgo"
@@ -522,4 +523,87 @@ var _ = Describe("Podman prune", func() {
 
 		podmanTest.Cleanup()
 	})
+
+	It("podman system prune --all --external fails", func() {
+		prune := podmanTest.Podman([]string{"system", "prune", "--all", "--enternal"})
+		prune.WaitWithDefaultTimeout()
+		Expect(prune).Should(Exit(125))
+	})
+
+	It("podman system prune --external leaves referenced containers", func() {
+		containerStorageDir := filepath.Join(podmanTest.Root, podmanTest.ImageCacheFS+"-containers")
+
+		create := podmanTest.Podman([]string{"create", "--name", "test", BB})
+		create.WaitWithDefaultTimeout()
+		Expect(create).Should(Exit(0))
+
+		// Container should exist
+		Expect(podmanTest.NumberOfContainers()).To(Equal(1))
+
+		// have: containers.json, containers.lock and container dir
+		dirents, err := os.ReadDir(containerStorageDir)
+		Expect(err).To(BeNil())
+		Expect(dirents).To(HaveLen(3))
+
+		prune := podmanTest.Podman([]string{"system", "prune", "--external", "-f"})
+		prune.WaitWithDefaultTimeout()
+		Expect(prune).Should(Exit(0))
+
+		// Container should still exist
+		Expect(podmanTest.NumberOfContainers()).To(Equal(1))
+
+		// still have: containers.json, containers.lock and container dir
+		dirents, err = os.ReadDir(containerStorageDir)
+		Expect(err).To(BeNil())
+		Expect(dirents).To(HaveLen(3))
+
+	})
+
+	It("podman system prune --external removes unreferenced containers", func() {
+		SkipIfRemote("Can't drop database while daemon running")
+
+		containerStorageDir := filepath.Join(podmanTest.Root, podmanTest.ImageCacheFS+"-containers")
+		dbDir := filepath.Join(podmanTest.Root, "libpod")
+
+		// Create container 1
+		create := podmanTest.Podman([]string{"create", "--name", "test", BB})
+		create.WaitWithDefaultTimeout()
+		Expect(create).Should(Exit(0))
+
+		Expect(podmanTest.NumberOfContainers()).To(Equal(1))
+
+		// containers.json, containers.lock and container 1 dir
+		dirents, err := os.ReadDir(containerStorageDir)
+		Expect(err).To(BeNil())
+		Expect(dirents).To(HaveLen(3))
+
+		// Drop podman database and storage, losing track of container 1 (but directory remains)
+		err = os.Remove(filepath.Join(containerStorageDir, "containers.json"))
+		Expect(err).To(BeNil())
+		err = os.RemoveAll(dbDir)
+		Expect(err).To(BeNil())
+
+		Expect(podmanTest.NumberOfContainers()).To(Equal(0))
+
+		// Create container 2
+		create = podmanTest.Podman([]string{"create", "--name", "test", BB})
+		create.WaitWithDefaultTimeout()
+		Expect(create).Should(Exit(0))
+
+		Expect(podmanTest.NumberOfContainers()).To(Equal(1))
+
+		// containers.json, containers.lock and container 1&2 dir
+		dirents, err = os.ReadDir(containerStorageDir)
+		Expect(err).To(BeNil())
+		Expect(dirents).To(HaveLen(4))
+
+		prune := podmanTest.Podman([]string{"system", "prune", "--external", "-f"})
+		prune.WaitWithDefaultTimeout()
+		Expect(prune).Should(Exit(0))
+
+		// container 1 dir should be gone now
+		dirents, err = os.ReadDir(containerStorageDir)
+		Expect(err).To(BeNil())
+		Expect(dirents).To(HaveLen(3))
+	})
 })