feat: command to list repositories in a remote registry (#525)

Signed-off-by: Juncheng Zhu <[email protected]>

cmd/oras/repository/cmd.go

@@ -24,6 +24,7 @@ func Cmd() *cobra.Command {
 	}
 
 	cmd.AddCommand(
+		listCmd(),
 		showTagsCmd(),
 	)
 	return cmd

cmd/oras/repository/list.go

@@ -0,0 +1,72 @@
+/*
+Copyright The ORAS Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package repository
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"oras.land/oras/cmd/oras/internal/option"
+)
+
+type repositoryOptions struct {
+	option.Remote
+	option.Common
+	hostname string
+	last     string
+}
+
+func listCmd() *cobra.Command {
+	var opts repositoryOptions
+	cmd := &cobra.Command{
+		Use:   "list [flags] REGISTRY",
+		Short: "[Preview] List the repositories under the registry",
+		Long: `[Preview] List the repositories under the registry
+
+** This command is in preview and under development. **
+
+Example - List the repositories under the registry:
+  oras repository list localhost:5000
+
+Example - List the repositories under the registry that include values lexically after last:
+  oras repository list localhost:5000 --last "last_repo"
+`,
+		Args:    cobra.ExactArgs(1),
+		Aliases: []string{"ls"},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			opts.hostname = args[0]
+			return listRepository(opts)
+		},
+	}
+
+	cmd.Flags().StringVar(&opts.last, "last", "", "start after the repository specified by `last`")
+	option.ApplyFlags(&opts, cmd.Flags())
+	return cmd
+}
+
+func listRepository(opts repositoryOptions) error {
+	ctx, _ := opts.SetLoggerLevel()
+	reg, err := opts.Remote.NewRegistry(opts.hostname, opts.Common)
+	if err != nil {
+		return err
+	}
+	return reg.Repositories(ctx, opts.last, func(repos []string) error {
+		for _, repo := range repos {
+			fmt.Println(repo)
+		}
+		return nil
+	})
+}

cmd/oras/repository/show-tags.go

@@ -32,7 +32,7 @@ type showTagsOptions struct {
 func showTagsCmd() *cobra.Command {
 	var opts showTagsOptions
 	cmd := &cobra.Command{
-		Use:   "show-tags REPO [flags]",
+		Use:   "show-tags [flags] REPOSITORY",
 		Short: "[Preview] Show tags of the target repository",
 		Long: `[Preview] Show tags of the target repository
 
@@ -61,13 +61,10 @@ func showTags(opts showTagsOptions) error {
 	if err != nil {
 		return err
 	}
-	if showTagErr := repo.Tags(ctx, opts.last, func(tags []string) error {
+	return repo.Tags(ctx, opts.last, func(tags []string) error {
 		for _, tag := range tags {
 			fmt.Println(tag)
 		}
 		return nil
-	}); showTagErr != nil {
-		return showTagErr
-	}
-	return nil
+	})
 }