feat: add --format flag to artifact inspect

Many commands support the `--format` flag which accept a go template to
allow for formatting for certain values, but it is not
yet implemented for artifact inspect command.

Adding this feature will allow easy formatting in scripts as well as
running it on a terminal.

This feature is implemented for artifact inspect by taking reference
from images and network commands implementation.

Fixes: [#27112](#27112)

Signed-off-by: Akash Yadav <akashyadav256526@gmail.com>

Author: skyraider256526

cmd/podman/artifact/inspect.go

@@ -1,23 +1,28 @@
 package artifact
 
 import (
+	"os"
+
 	"github.com/containers/podman/v5/cmd/podman/common"
+	"github.com/containers/podman/v5/cmd/podman/inspect"
 	"github.com/containers/podman/v5/cmd/podman/registry"
 	"github.com/containers/podman/v5/cmd/podman/utils"
 	"github.com/containers/podman/v5/pkg/domain/entities"
 	"github.com/spf13/cobra"
+	"go.podman.io/common/pkg/report"
 )
 
 var (
 	inspectCmd = &cobra.Command{
 		Use:               "inspect [ARTIFACT...]",
 		Short:             "Inspect an OCI artifact",
 		Long:              "Provide details on an OCI artifact",
-		RunE:              inspect,
+		RunE:              artifactInspect,
 		Args:              cobra.MinimumNArgs(1),
 		ValidArgsFunction: common.AutocompleteArtifacts,
 		Example:           `podman artifact inspect quay.io/myimage/myartifact:latest`,
 	}
+	inspectOpts *entities.InspectOptions
 )
 
 func init() {
@@ -26,25 +31,45 @@ func init() {
 		Parent:  artifactCmd,
 	})
 
-	// TODO When things firm up on inspect looks, we can do a format implementation
-	// flags := inspectCmd.Flags()
-	// formatFlagName := "format"
-	// flags.StringVar(&inspectFlag.format, formatFlagName, "", "Format volume output using JSON or a Go template")
+	inspectOpts = new(entities.InspectOptions)
+
+	flags := inspectCmd.Flags()
+	formatFlagName := "format"
+	flags.StringVarP(&inspectOpts.Format, formatFlagName, "f", "json", "Format volume output using JSON or a Go template")
 
 	// This is something we wanted to do but did not seem important enough for initial PR
 	// remoteFlagName := "remote"
 	// flags.BoolVar(&inspectFlag.remote, remoteFlagName, false, "Inspect the image on a container image registry")
 
 	// TODO When the inspect structure has been defined, we need to uncomment and redirect this.  Reminder, this
 	// will also need to be reflected in the podman-artifact-inspect man page
-	// _ = inspectCmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(&machine.InspectInfo{}))
+	_ = inspectCmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(&entities.ArtifactInspectReport{}))
 }
 
-func inspect(_ *cobra.Command, args []string) error {
+func artifactInspect(_ *cobra.Command, args []string) error {
 	artifactOptions := entities.ArtifactInspectOptions{}
 	inspectData, err := registry.ImageEngine().ArtifactInspect(registry.Context(), args[0], artifactOptions)
 	if err != nil {
 		return err
 	}
-	return utils.PrintGenericJSON(inspectData)
+
+	switch {
+	case report.IsJSON(inspectOpts.Format) || inspectOpts.Format == "":
+		return utils.PrintGenericJSON(inspectData)
+	default:
+		// Landing here implies user has given a custom --format
+		var rpt *report.Formatter
+		format := inspect.InspectNormalize(inspectOpts.Format, inspectOpts.Type)
+		rpt, err = report.New(os.Stdout, "inspect").Parse(report.OriginUser, format)
+		if err != nil {
+			return err
+		}
+		defer rpt.Flush()
+
+		// Storing and passing inspectData in an array to [Execute] is workaround to avoid getting an error.
+		// Which seems to happen when type passed to [Execute] is not a slice.
+		// Error: template: inspect:1:8: executing "inspect" at <.>: range can't iterate over {0x6600020c444 sha256:4bafff5c1b2c950651101d22d3dbf76744446aeb5f79fc926674e0db1083qew456}
+		data := []any{inspectData}
+		return rpt.Execute(data)
+	}
 }

cmd/podman/inspect/inspect.go

@@ -176,7 +176,7 @@ func (i *inspector) inspect(namesOrIDs []string) error {
 	default:
 		// Landing here implies user has given a custom --format
 		var rpt *report.Formatter
-		format := inspectNormalize(i.options.Format, i.options.Type)
+		format := InspectNormalize(i.options.Format, i.options.Type)
 		rpt, err = report.New(os.Stdout, "inspect").Parse(report.OriginUser, format)
 		if err != nil {
 			return err
@@ -258,7 +258,22 @@ func (i *inspector) inspectAll(ctx context.Context, namesOrIDs []string) ([]any,
 	return data, allErrs, nil
 }
 
-func inspectNormalize(row string, inspectType string) string {
+// InspectNormalize modifies a given row string based on the specified inspect type.
+// It replaces specific field names within the row string for standardization.
+// For the `image` inspect type, it includes additional field replacements like `.Config.Healthcheck`.
+//
+// Parameters:
+// - row: The input string that represents a data row to be modified.
+// - inspectType: The type of inspection (e.g., "image") to determine specific replacements.
+//
+// Returns:
+// - A new string with the necessary replacements applied based on the inspect type.
+//
+// InspectNormalize does not need to be exported but to avoid de-duplication of code. We had to export it.
+// It can be reverted back once `podman artifact inspect` can use [Inspect] to fetch artifact data instead of
+// fetching it itself.
+// The reason why we did it in this way can be further read [here](https://github.com/containers/podman/pull/27182#issuecomment-3402465389).
+func InspectNormalize(row string, inspectType string) string {
 	m := regexp.MustCompile(`{{\s*\.Id\s*}}`)
 	row = m.ReplaceAllString(row, "{{.ID}}")
 

docs/source/markdown/podman-artifact-inspect.1.md

@@ -20,15 +20,58 @@ annotation using RFC3339Nano format, showing when the artifact was initially cre
 
 ## OPTIONS
 
-#### **--help**
+#### **--format**, **-f**=*format*
 
-Print usage statement.
+Format the output using the given Go template.
+The keys of the returned JSON can be used as the values for the --format flag (see examples below).
+
+Valid placeholders for the Go template are listed below:
+
+| **Placeholder**          | **Description**                                    |
+| ------------------------ | -------------------------------------------------- |
+| .Artifact ...            | Artifact details (nested struct)                   |
+| .Digest                  | Artifact digest (sha256:+64-char hash)             |
+| .Manifest ...            | Artifact manifest details (struct)                 |
+| .Name                    | Artifact name (string)                             |
+| .TotalSizeBytes          | Total Size of the artifact in bytes                |
 
 ## EXAMPLES
 
 Inspect an OCI image in the local store.
-```
+
+```shell
 $ podman artifact inspect quay.io/myartifact/myml:latest
+{
+     "Manifest": {
+          "schemaVersion": 2,
+          "mediaType": "application/vnd.oci.image.manifest.v1+json",
+          "config": {
+               "mediaType": "application/vnd.oci.empty.v1+json",
+               "digest": "sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a",
+               "size": 2,
+               "data": "e30="
+          },
+          "layers": [
+               {
+                    "mediaType": "text/plain; charset=utf-8",
+                    "digest": "sha256:f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2",
+                    "size": 5,
+                    "annotations": {
+                         "org.opencontainers.image.title": "foobar.txt"
+                    }
+               }
+          ]
+     },
+     "Name": "quay.io/myartifact/mytxt:latest",
+     "Digest": "sha256:6c28fa07a5b0a1cee29862c1f6ea38a66df982495b14da2c052427eb628ed8c6"
+}
+```
+
+Inspect artifact digest for the specified artifact:
+
+```shell
+$ podman artifact inspect quay.io/myartifact/mytxt:latest --format {{.Digest}}
+sha256:6c28fa07a5b0a1cee29862c1f6ea38a66df982495b14da2c052427eb628ed8c6
 ```
 
 ## SEE ALSO

test/e2e/artifact_test.go

@@ -636,6 +636,18 @@ var _ = Describe("Podman artifact", func() {
 		// Verify we have 2 layers
 		Expect(a.Manifest.Layers).To(HaveLen(2))
 	})
+
+	It("podman artifact inspect with --format", func() {
+		artifact1File, err := createArtifactFile(4192)
+		Expect(err).ToNot(HaveOccurred())
+		artifact1Name := "localhost/test/artifact1"
+		addArtifact1 := podmanTest.PodmanExitCleanly("artifact", "add", artifact1Name, artifact1File)
+
+		artifactDigest := addArtifact1.OutputToString()
+
+		podmanTest.PodmanExitCleanly("artifact", "inspect", artifactDigest, "--format", "{{.Digest}}")
+		podmanTest.PodmanExitCleanly("artifact", "inspect", artifactDigest[:12], "--format", "{{.Name}}")
+	})
 })
 
 func digestToFilename(digest string) string {