image prune: support removing external containers

Support removing external containers (e.g., build containers) during
image prune.

Fixes: containers#11472
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

cmd/podman/images/prune.go

@@ -41,6 +41,7 @@ func init() {
 
 	flags := pruneCmd.Flags()
 	flags.BoolVarP(&pruneOpts.All, "all", "a", false, "Remove all images not in use by containers, not just dangling ones")
+	flags.BoolVarP(&pruneOpts.External, "external", "", false, "Remove images even when they are used by external containers (e.g., by build containers)")
 	flags.BoolVarP(&force, "force", "f", false, "Do not prompt for confirmation")
 
 	filterFlagName := "filter"

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

@@ -17,6 +17,10 @@ The image prune command does not prune cache images that only use layers that ar
 
 Remove dangling images and images that have no associated containers.
 
+#### **--external**
+
+Remove images even when they are used by external containers (e.g., build containers).
+
 #### **--filter**=*filters*
 
 Provide filter values.

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/containernetworking/cni v1.0.1
 	github.com/containernetworking/plugins v1.0.1
 	github.com/containers/buildah v1.23.0
-	github.com/containers/common v0.46.0
+	github.com/containers/common v0.46.1-0.20210928081721-32e20295f1c6
 	github.com/containers/conmon v2.0.20+incompatible
 	github.com/containers/image/v5 v5.16.0
 	github.com/containers/ocicrypt v1.1.2
@@ -61,7 +61,6 @@ require (
 	github.com/syndtr/gocapability v0.0.0-20200815063812-42c35b437635
 	github.com/uber/jaeger-client-go v2.29.1+incompatible
 	github.com/vbauerster/mpb/v6 v6.0.4
-	github.com/vbauerster/mpb/v7 v7.1.4 // indirect
 	github.com/vishvananda/netlink v1.1.1-0.20210330154013-f5de75959ad5
 	go.etcd.io/bbolt v1.3.6
 	golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97

go.sum

@@ -250,8 +250,8 @@ github.com/containernetworking/plugins v1.0.1/go.mod h1:QHCfGpaTwYTbbH+nZXKVTxNB
 github.com/containers/buildah v1.23.0 h1:qGIeSNOczUHzvnaaOS29HSMiYAjw6JgIXYksAyvqnLs=
 github.com/containers/buildah v1.23.0/go.mod h1:K0iMKgy/MffkkgELBXhSXwTy2HTT6hM0X8qruDR1FwU=
 github.com/containers/common v0.44.0/go.mod h1:7sdP4vmI5Bm6FPFxb3lvAh1Iktb6tiO1MzjUzhxdoGo=
-github.com/containers/common v0.46.0 h1:95zB7kYBQJW+aK5xxZnaobCwoPyYOf85Y0yUx0E5aRg=
-github.com/containers/common v0.46.0/go.mod h1:zxv7KjdYddSGoWuLUVp6eSb++Ow1zmSMB2jwxuNB4cU=
+github.com/containers/common v0.46.1-0.20210928081721-32e20295f1c6 h1:DojkCc4a9f3WB25Fk0GDap1/OkKU9UmDLvPJyqw3TBc=
+github.com/containers/common v0.46.1-0.20210928081721-32e20295f1c6/go.mod h1:L4+sJlqi+R7frlbiWBW0baPra/cH8u5ZYwbxkukw3Lk=
 github.com/containers/conmon v2.0.20+incompatible h1:YbCVSFSCqFjjVwHTPINGdMX1F6JXHGTUje2ZYobNrkg=
 github.com/containers/conmon v2.0.20+incompatible/go.mod h1:hgwZ2mtuDrppv78a/cOBNiCm6O0UMWGx1mu7P00nu5I=
 github.com/containers/image/v5 v5.16.0 h1:WQcNSzb7+ngS2cfynx0vUwhk+scpgiKlldVcsF8GPbI=

libpod/runtime_img.go

@@ -48,6 +48,27 @@ func (r *Runtime) RemoveContainersForImageCallback(ctx context.Context) libimage
 	}
 }
 
+// IsExternalContainerCallback returns a callback that be used in `libimage` to
+// figure out whether a given container is an external one.  A container is
+// considered external if it is not present in libpod's database.
+func (r *Runtime) IsExternalContainerCallback(_ context.Context) libimage.IsExternalContainerFunc {
+	// NOTE: pruning external containers is subject to race conditions
+	// (e.g., when a container gets removed). To address this and similar
+	// races, pruning had to happen inside c/storage.  Containers has to be
+	// labelled with "podman/libpod" along with callbacks similar to
+	// libimage.
+	return func(idOrName string) (bool, error) {
+		_, err := r.LookupContainer(idOrName)
+		if err == nil {
+			return false, nil
+		}
+		if errors.Is(err, define.ErrNoSuchCtr) {
+			return true, nil
+		}
+		return false, nil
+	}
+}
+
 // newBuildEvent creates a new event based on completion of a built image
 func (r *Runtime) newImageBuildCompleteEvent(idOrName string) {
 	e := events.NewEvent(events.Build)

pkg/api/handlers/libpod/images.go

@@ -150,7 +150,8 @@ func PruneImages(w http.ResponseWriter, r *http.Request) {
 	runtime := r.Context().Value(api.RuntimeKey).(*libpod.Runtime)
 	decoder := r.Context().Value(api.DecoderKey).(*schema.Decoder)
 	query := struct {
-		All bool `schema:"all"`
+		All      bool `schema:"all"`
+		External bool `schema:"external"`
 	}{
 		// override any golang type defaults
 	}
@@ -190,8 +191,9 @@ func PruneImages(w http.ResponseWriter, r *http.Request) {
 	imageEngine := abi.ImageEngine{Libpod: runtime}
 
 	pruneOptions := entities.ImagePruneOptions{
-		All:    query.All,
-		Filter: libpodFilters,
+		All:      query.All,
+		External: query.External,
+		Filter:   libpodFilters,
 	}
 	imagePruneReports, err := imageEngine.Prune(r.Context(), pruneOptions)
 	if err != nil {

pkg/api/server/register_images.go

@@ -1050,6 +1050,12 @@ func (s *APIServer) registerImagesHandlers(r *mux.Router) error {
 	//    description: |
 	//      Remove all images not in use by containers, not just dangling ones
 	//  - in: query
+	//    name: external
+	//    default: false
+	//    type: boolean
+	//    description: |
+	//      Remove images even when they are used by external containers (e.g, by build containers)
+	//  - in: query
 	//    name: filters
 	//    type: string
 	//    description: |

pkg/bindings/images/types.go

@@ -74,6 +74,8 @@ type ExportOptions struct {
 type PruneOptions struct {
 	// Prune all images
 	All *bool
+	// Prune images even when they're used by external containers
+	External *bool
 	// Filters to apply when pruning images
 	Filters map[string][]string
 }

pkg/domain/entities/images.go

@@ -251,8 +251,9 @@ type ImageListOptions struct {
 }
 
 type ImagePruneOptions struct {
-	All    bool     `json:"all" schema:"all"`
-	Filter []string `json:"filter" schema:"filter"`
+	All      bool     `json:"all" schema:"all"`
+	External bool     `json:"external" schema:"external"`
+	Filter   []string `json:"filter" schema:"filter"`
 }
 
 type ImageTagOptions struct{}

pkg/domain/infra/abi/images.go

@@ -41,13 +41,21 @@ func (ir *ImageEngine) Exists(_ context.Context, nameOrID string) (*entities.Boo
 
 func (ir *ImageEngine) Prune(ctx context.Context, opts entities.ImagePruneOptions) ([]*reports.PruneReport, error) {
 	pruneOptions := &libimage.RemoveImagesOptions{
-		Filters:  append(opts.Filter, "containers=false", "readonly=false"),
-		WithSize: true,
+		RemoveContainerFunc:     ir.Libpod.RemoveContainersForImageCallback(ctx),
+		IsExternalContainerFunc: ir.Libpod.IsExternalContainerCallback(ctx),
+		ExternalContainers:      opts.External,
+		Filters:                 append(opts.Filter, "readonly=false"),
+		WithSize:                true,
 	}
 
 	if !opts.All {
 		pruneOptions.Filters = append(pruneOptions.Filters, "dangling=true")
 	}
+	if opts.External {
+		pruneOptions.Filters = append(pruneOptions.Filters, "containers=external")
+	} else {
+		pruneOptions.Filters = append(pruneOptions.Filters, "containers=false")
+	}
 
 	var pruneReports []*reports.PruneReport
 

pkg/domain/infra/tunnel/images.go

@@ -95,7 +95,7 @@ func (ir *ImageEngine) Prune(ctx context.Context, opts entities.ImagePruneOption
 		f := strings.Split(filter, "=")
 		filters[f[0]] = f[1:]
 	}
-	options := new(images.PruneOptions).WithAll(opts.All).WithFilters(filters)
+	options := new(images.PruneOptions).WithAll(opts.All).WithFilters(filters).WithExternal(opts.External)
 	reports, err := images.Prune(ir.ClientCtx, options)
 	if err != nil {
 		return nil, err

test/system/040-ps.bats

@@ -92,24 +92,38 @@ load helpers
     # Force a buildah timeout; this leaves a buildah container behind
     PODMAN_TIMEOUT=5 run_podman 124 build -t thiswillneverexist - <<EOF
 FROM $IMAGE
+RUN touch /intermediate.image.to.be.pruned
 RUN sleep 30
 EOF
 
     run_podman ps -a
-    is "${#lines[@]}" "1" "podman ps -a does not see buildah container"
+    is "${#lines[@]}" "1" "podman ps -a does not see buildah containers"
 
     run_podman ps --external -a
-    is "${#lines[@]}" "2" "podman ps -a --external sees buildah container"
+    is "${#lines[@]}" "3" "podman ps -a --external sees buildah containers"
     is "${lines[1]}" \
        "[0-9a-f]\{12\} \+$IMAGE *buildah .* seconds ago .* storage .* ${PODMAN_TEST_IMAGE_NAME}-working-container" \
        "podman ps --external"
 
-    cid="${lines[1]:0:12}"
-
     # 'rm -a' should be a NOP
     run_podman rm -a
     run_podman ps --external -a
-    is "${#lines[@]}" "2" "podman ps -a --external sees buildah container"
+    is "${#lines[@]}" "3" "podman ps -a --external sees buildah containers"
+
+    # Cannot prune intermediate image as it's being used by a buildah
+    # container.
+    run_podman image prune -f
+    is "$output" "" "No image is pruned"
+
+    # --external for removing buildah containers.
+    run_podman image prune -f --external
+    is "${#lines[@]}" "1" "Image used by build container is pruned"
+
+    # One buildah container has been removed.
+    run_podman ps --external -a
+    is "${#lines[@]}" "2" "podman ps -a --external sees buildah containers"
+
+    cid="${lines[1]:0:12}"
 
     # We can't rm it without -f, but podman should issue a helpful message
     run_podman 2 rm "$cid"

test/system/330-corrupt-images.bats

@@ -78,7 +78,7 @@ function _corrupt_image_test() {
 
         # Run the requested command. Confirm it succeeds, with suitable warnings
         run_podman $*
-        is "$output" ".*error determining parent of image.*ignoring the error" \
+        is "$output" ".*Failed to determine parent of image.*ignoring the error" \
            "$* with missing $what_to_rm"
 
         run_podman images -a --noheading