manifest: add support for buildah manifest exists

Adds support for `buildah manifest exists <name>` which tells user if
requested manifest is present in local storage or not, if manifest is
present in local-storage command exits with exit code 0 otherwise 1.

Similar to: https://docs.podman.io/en/latest/markdown/podman-manifest-exists.1.html

Closes: https://github.com/containers/buildah/issues/4217

Signed-off-by: Aditya R <arajan@redhat.com>

cmd/buildah/manifest.go

@@ -55,6 +55,7 @@ func init() {
 		manifestInspectDescription  = "\n  Display the contents of a manifest list or image index."
 		manifestPushDescription     = "\n  Pushes manifest lists and image indexes to registries."
 		manifestRmDescription       = "\n  Remove one or more manifest lists from local storage."
+		manifestExistsDescription   = "\n  Check if a manifest list exists in local storage."
 		manifestCreateOpts          manifestCreateOpts
 		manifestAddOpts             manifestAddOpts
 		manifestRemoveOpts          manifestRemoveOpts
@@ -155,6 +156,19 @@ func init() {
 	manifestRemoveCommand.SetUsageTemplate(UsageTemplate())
 	manifestCommand.AddCommand(manifestRemoveCommand)
 
+	manifestExistsCommand := &cobra.Command{
+		Use:   "exists",
+		Short: "Check if a manifest list exists in local storage",
+		Long:  manifestExistsDescription,
+		Args:  cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return manifestExistsCmd(cmd, args)
+		},
+		Example: "buildah manifest exists mylist",
+	}
+	manifestExistsCommand.SetUsageTemplate(UsageTemplate())
+	manifestCommand.AddCommand(manifestExistsCommand)
+
 	manifestAnnotateCommand := &cobra.Command{
 		Use:   "annotate",
 		Short: "Add or update information about an entry in a manifest list or image index",
@@ -237,6 +251,39 @@ func init() {
 	manifestCommand.AddCommand(manifestRmCommand)
 }
 
+func manifestExistsCmd(c *cobra.Command, args []string) error {
+	if len(args) == 0 {
+		return errors.New("At least a name must be specified for the list")
+	}
+	name := args[0]
+
+	store, err := getStore(c)
+	if err != nil {
+		return err
+	}
+
+	systemContext, err := parse.SystemContextFromOptions(c)
+	if err != nil {
+		return fmt.Errorf("error building system context: %w", err)
+	}
+	runtime, err := libimage.RuntimeFromStore(store, &libimage.RuntimeOptions{SystemContext: systemContext})
+	if err != nil {
+		return err
+	}
+
+	_, err = runtime.LookupManifestList(name)
+	if err != nil {
+		if errors.Is(err, storage.ErrImageUnknown) {
+			if err := shutdownStore(c); err != nil {
+				return err
+			}
+			os.Exit(1)
+		}
+		return err
+	}
+	return nil
+}
+
 func manifestCreateCmd(c *cobra.Command, args []string, opts manifestCreateOpts) error {
 	if len(args) == 0 {
 		return errors.New("At least a name must be specified for the list")

docs/buildah-manifest-exists.1.md

@@ -0,0 +1,40 @@
+% buildah-manifest-exists(1)
+
+## NAME
+buildah\-manifest\-exists - Check if the given manifest list exists in local storage
+
+## SYNOPSIS
+**buildah manifest exists** *manifest*
+
+## DESCRIPTION
+**buildah manifest exists** checks if a manifest list exists in local storage. Buildah will
+return an exit code of `0` when the manifest list is found. A `1` will be returned otherwise.
+An exit code of `125` indicates there was another issue.
+
+
+## OPTIONS
+
+#### **--help**, **-h**
+
+Print usage statement.
+
+## EXAMPLE
+
+Check if a manifest list called `list1` exists (the manifest list does actually exist).
+```
+$ buildah manifest exists list1
+$ echo $?
+0
+$
+```
+
+Check if an manifest called `mylist` exists (the manifest list does not actually exist).
+```
+$ buildah manifest exists mylist
+$ echo $?
+1
+$
+```
+
+## SEE ALSO
+**[buildah(1)](buildah.1.md)**, **[buildah-manifest(1)](buildah-manifest.1.md)**

docs/buildah-manifest.1.md

@@ -22,6 +22,7 @@ The `buildah manifest` command provides subcommands which can be used to:
 | add      | [buildah-manifest-add(1)](buildah-manifest-add.1.md)           | Add an image to a manifest list or image index.                             |
 | annotate | [buildah-manifest-annotate(1)](buildah-manifest-annotate.1.md) | Add or update information about an image in a manifest list or image index. |
 | create   | [buildah-manifest-create(1)](buildah-manifest-create.1.md)     | Create a manifest list or image index.                                      |
+| exists   | [buildah-manifest-exists(1)](buildah-manifest-exists.1.md)     | Check if a manifest list exists in local storage.                           |
 | inspect  | [buildah-manifest-inspect(1)](buildah-manifest-inspect.1.md)   | Display the contents of a manifest list or image index.                     |
 | push     | [buildah-manifest-push(1)](buildah-manifest-push.1.md)         | Push a manifest list or image index to a registry or other location.        |
 | remove   | [buildah-manifest-remove(1)](buildah-manifest-remove.1.md)     | Remove an image from a manifest list or image index.                        |

tests/lists.bats

@@ -18,6 +18,10 @@ IMAGE_LIST_S390X_INSTANCE_DIGEST=sha256:882a20ee0df7399a445285361d38b711c299ca09
     assert "$output" =~ "that name is already in use"
     run_buildah manifest create --amend foo
     assert "$output" == "$listid"
+    # since manifest exists in local storage this should exit with `0`
+    run_buildah manifest exists foo
+    # since manifest does not exist in local storage this should exit with `1`
+    run_buildah 1 manifest exists foo2
 }
 
 @test "manifest-inspect-id" {
@@ -29,6 +33,10 @@ IMAGE_LIST_S390X_INSTANCE_DIGEST=sha256:882a20ee0df7399a445285361d38b711c299ca09
 @test "manifest-add" {
     run_buildah manifest create foo
     run_buildah manifest add foo ${IMAGE_LIST}
+    # since manifest exists in local storage this should exit with `0`
+    run_buildah manifest exists foo
+    # since manifest does not exist in local storage this should exit with `1`
+    run_buildah 1 manifest exists foo2
     run_buildah manifest rm foo
 }
 
@@ -211,4 +219,8 @@ IMAGE_LIST_S390X_INSTANCE_DIGEST=sha256:882a20ee0df7399a445285361d38b711c299ca09
     run_buildah manifest inspect test
     # must contain amd64
     expect_output --substring "amd64"
+    # since manifest exists in local storage this should exit with `0`
+    run_buildah manifest exists test:latest
+    # since manifest does not exist in local storage this should exit with `1`
+    run_buildah 1 manifest exists test2
 }