Add --show-kptfile option to porchctl rpkg get command (kptdev#513)

* Add --show-kptfile flag to porchctl get command to display Kptfile content

Signed-off-by: Aravindhan Ayyanathan <aravindhan.a@est.tech>

* Address copilot review comments

Signed-off-by: Aravindhan Ayyanathan <aravindhan.a@est.tech>

* Refactor namespace resolution and update documentation for --show-kptfile flag

Signed-off-by: Aravindhan Ayyanathan <aravindhan.a@est.tech>

---------

Signed-off-by: Aravindhan Ayyanathan <aravindhan.a@est.tech>

Author: aravindtga

docs/content/en/docs/4_tutorials_and_how-tos/working_with_package_revisions/inspecting-packages.md

@@ -140,6 +140,47 @@ Use `jq` to extract specific fields: `porchctl rpkg get <name> -n default -o jso
 
 ---
 
+### Viewing the Root Kptfile
+
+Display the root Kptfile of a specific package revision without downloading the entire package
+
+```bash
+porchctl rpkg get porch-test.my-app.v1 --show-kptfile --namespace default
+```
+
+**What this does:**
+
+- Fetches the PackageRevisionResources for the specified package revision
+- Extracts and displays only the root `Kptfile`
+- Useful for quickly inspecting package metadata, pipeline configuration, and status
+
+**Example output:**
+
+```yaml
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: my-app
+info:
+  description: My application package
+pipeline:
+  mutators:
+  - image: ghcr.io/kptdev/krm-functions-catalog/set-namespace:v0.4.5
+    configMap:
+      namespace: production
+status:
+  conditions:
+  - type: Rendered
+    status: "True"
+    reason: RenderSuccess
+```
+
+{{% alert title="Note" color="primary" %}}
+`--show-kptfile` requires exactly one package revision name and cannot be combined with `--name`, `--revision`, `--workspace`, or `--all-namespaces`.
+{{% /alert %}}
+
+---
+
 ### Reading PackageRevision Resources
 
 Read the actual contents of a PackageRevision:

docs/content/en/docs/7_cli_api/porchctl.md

@@ -406,6 +406,7 @@ porchctl rpkg get [PACKAGE] [flags]
 | `--name string` | Filter by package name (substring match) | |
 | `--revision int` | Filter by revision number | `-2` (all) |
 | `--workspace string` | Filter by workspace name | |
+| `--show-kptfile` | Display the root Kptfile of the specified package revision. Requires exactly one package revision name. Cannot be combined with `--name`, `--revision`, `--workspace`, or `-A`. | |
 | `-A, --all-namespaces` | List across all namespaces | |
 | `-o, --output string` | Output format | |
 | `--no-headers` | Don't print headers | |
@@ -425,6 +426,9 @@ porchctl rpkg get --namespace=example-namespace
 
 # Get all with revision 0 (Draft/Proposed)
 porchctl rpkg get --revision=0
+
+# Display the root Kptfile of a specific package revision
+porchctl rpkg get example-repo.example-package-name.example-workspace --show-kptfile --namespace=example-namespace
 ```
 
 ---

pkg/cli/commands/rpkg/docs/docs.go

@@ -146,6 +146,11 @@ Flags:
   --revision
     Revision of the package to get. Any package whose revision
     matches this value will be included in the results.
+
+  --show-kptfile
+    Display the root Kptfile of the specified package revision.
+    Requires exactly one package revision name as an argument.
+    Cannot be combined with --name, --revision, --workspace, or --all-namespaces.
 `
 var GetExamples = `
   # get a specific package revision using its kubernetes resource name in the 'example-namespace' namespace
@@ -159,6 +164,9 @@ var GetExamples = `
 
   # get all package revisions with revision '0'
   $ porchctl rpkg get --revision=0
+
+  # display the root Kptfile of a specific package revision
+  $ porchctl rpkg get example-repo.example-package-name.example-workspace --show-kptfile --namespace=example-namespace
 `
 
 var InitShort = `Initializes a new package revision in a repository.`

pkg/cli/commands/rpkg/get/command.go

@@ -20,8 +20,10 @@ import (
 	"strconv"
 	"strings"
 
+	kptfilev1 "github.com/kptdev/kpt/pkg/api/kptfile/v1"
 	"github.com/kptdev/kpt/pkg/lib/errors"
 	"github.com/kptdev/kpt/pkg/lib/util/cmdutil"
+	porchapi "github.com/nephio-project/porch/api/porch/v1alpha1"
 	cliutils "github.com/nephio-project/porch/internal/cliutils"
 	"github.com/nephio-project/porch/pkg/cli/commands/rpkg/docs"
 	"github.com/spf13/cobra"
@@ -35,6 +37,7 @@ import (
 	"k8s.io/client-go/rest"
 	"k8s.io/klog/v2"
 	"k8s.io/kubectl/pkg/cmd/get"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 )
 
 const (
@@ -66,6 +69,7 @@ func newRunner(ctx context.Context, rcg *genericclioptions.ConfigFlags) *runner
 	cmd.Flags().Int64Var(&r.revision, "revision", -2, "Revision of the packages to get. Any package whose revision matches this value will be included in the results.")
 	cmd.Flags().StringVar(&r.workspace, "workspace", "",
 		"WorkspaceName of the packages to get. Any package whose workspaceName matches this value will be included in the results.")
+	cmd.Flags().BoolVar(&r.showKptfile, "show-kptfile", false, "Display the root Kptfile of the specified package revision. Requires a single package revision name as an argument.")
 
 	r.getFlags.AddFlags(cmd)
 	r.printFlags.AddFlags(cmd)
@@ -85,18 +89,22 @@ type runner struct {
 	packageName string
 	revision    int64
 	workspace   string
+	showKptfile bool
 	printFlags  *get.PrintFlags
 
 	requestTable bool
+
+	// client is used for --show-kptfile; set in preRunE or injected in tests
+	client client.Client
 }
 
-func (r *runner) preRunE(cmd *cobra.Command, _ []string) error {
-	// Check for --namespace or -n flag specified without a value
-	nsFlag := cmd.Flag("namespace")
-	nFlag := cmd.Flag("n")
-	if (nsFlag != nil && nsFlag.Changed && nsFlag.Value.String() == "") ||
-		(nFlag != nil && nFlag.Changed && nFlag.Value.String() == "") {
-		return fmt.Errorf("error: namespace flag specified without a value; please provide a value for --namespace/-n or omit the flag")
+func (r *runner) preRunE(cmd *cobra.Command, args []string) error {
+	if err := r.validateNamespaceFlag(cmd); err != nil {
+		return err
+	}
+
+	if r.showKptfile {
+		return r.preRunShowKptfile(args)
 	}
 
 	// Print the namespace if we're spanning namespaces
@@ -113,9 +121,65 @@ func (r *runner) preRunE(cmd *cobra.Command, _ []string) error {
 	return nil
 }
 
+func (r *runner) validateNamespaceFlag(cmd *cobra.Command) error {
+	nsFlag := cmd.Flag("namespace")
+	nFlag := cmd.Flag("n")
+	if (nsFlag != nil && nsFlag.Changed && nsFlag.Value.String() == "") ||
+		(nFlag != nil && nFlag.Changed && nFlag.Value.String() == "") {
+		return fmt.Errorf("namespace flag specified without a value; please provide a value for --namespace/-n or omit the flag")
+	}
+	return nil
+}
+
+// resolveNamespace ensures a namespace is set on ConfigFlags, falling back to
+// the kubeconfig default context namespace when none was explicitly provided.
+func (r *runner) resolveNamespace() error {
+	if r.getFlags.ConfigFlags.Namespace == nil || *r.getFlags.ConfigFlags.Namespace == "" {
+		namespace, _, err := r.getFlags.ConfigFlags.ToRawKubeConfigLoader().Namespace()
+		if err != nil {
+			return fmt.Errorf("error resolving namespace from kubeconfig: %w", err)
+		}
+		if namespace == "" {
+			return fmt.Errorf("namespace is not configured; please provide --namespace or set a default namespace in your kubeconfig")
+		}
+		r.getFlags.ConfigFlags.Namespace = &namespace
+	}
+	return nil
+}
+
+func (r *runner) preRunShowKptfile(args []string) error {
+	if len(args) != 1 {
+		return fmt.Errorf("--show-kptfile requires exactly one package revision name as an argument")
+	}
+	if r.packageName != "" || r.revision != -2 || r.workspace != "" {
+		return fmt.Errorf("--show-kptfile cannot be combined with --name, --revision, or --workspace")
+	}
+	if r.getFlags.AllNamespaces {
+		return fmt.Errorf("--show-kptfile cannot be combined with --all-namespaces")
+	}
+	if err := r.resolveNamespace(); err != nil {
+		return err
+	}
+	if r.client == nil {
+		c, err := cliutils.CreateClientWithFlags(r.getFlags.ConfigFlags)
+		if err != nil {
+			return err
+		}
+		r.client = c
+	}
+	return nil
+}
+
 func (r *runner) runE(cmd *cobra.Command, args []string) error {
 	const op errors.Op = command + ".runE"
 
+	if r.showKptfile {
+		if len(args) != 1 {
+			return errors.E(op, fmt.Errorf("--show-kptfile requires exactly one package revision name as an argument"))
+		}
+		return r.showKptfileContent(cmd, args[0])
+	}
+
 	var objs []runtime.Object
 	b, err := r.getFlags.ResourceBuilder()
 	if err != nil {
@@ -322,3 +386,33 @@ func (r *runner) filterTableRows(table *metav1.Table) error {
 	table.Rows = filtered
 	return nil
 }
+
+func (r *runner) showKptfileContent(cmd *cobra.Command, name string) error {
+	const op errors.Op = command + ".showKptfileContent"
+
+	if err := r.resolveNamespace(); err != nil {
+		return errors.E(op, err)
+	}
+
+	if r.client == nil {
+		return errors.E(op, fmt.Errorf("client is not initialized; ensure preRunE has been executed"))
+	}
+
+	var resources porchapi.PackageRevisionResources
+	if err := r.client.Get(r.ctx, client.ObjectKey{
+		Namespace: *r.getFlags.ConfigFlags.Namespace,
+		Name:      name,
+	}, &resources); err != nil {
+		return errors.E(op, err)
+	}
+
+	kptfile, ok := resources.Spec.Resources[kptfilev1.KptFileName]
+	if !ok {
+		return errors.E(op, fmt.Errorf("package revision %q does not contain a root Kptfile", name))
+	}
+
+	if _, err := fmt.Fprint(cmd.OutOrStdout(), kptfile); err != nil {
+		return errors.E(op, err)
+	}
+	return nil
+}