Add ContainerRepositories API

Add show endpoint for container repositories not
nested beneath projects or groups.

changelogs/unreleased/209916-container-repository-api.yml

+---
+title: Add container repositories API
+merge_request: 46495
+author:
+type: added

doc/api/container_registry.md

@@ -124,6 +124,48 @@ Example response:
 ]
 ```
 
+## Get details of a single repository
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/209916) in GitLab 13.6.
+
+Get details of a registry repository.
+
+```plaintext
+GET /registry/repositories/:id
+```
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `id`      | integer/string | yes | The ID of the registry repository accessible by the authenticated user. |
+| `tags`      | boolean | no | If the parameter is included as `true`, the response includes an array of `"tags"`. |
+| `tags_count` | boolean | no | If the parameter is included as `true`, the response includes `"tags_count"`. |
+
+```shell
+curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/registry/repositories/2?tags=true&tags_count=true"
+```
+
+Example response:
+
+```json
+{
+  "id": 2,
+  "name": "",
+  "path": "group/project",
+  "project_id": 9,
+  "location": "gitlab.example.com:5000/group/project",
+  "created_at": "2019-01-10T13:38:57.391Z",
+  "cleanup_policy_started_at": "2020-08-17T03:12:35.489Z",
+  "tags_count": 1,
+  "tags": [
+    {
+      "name": "0.0.1",
+      "path": "group/project:0.0.1",
+      "location": "gitlab.example.com:5000/group/project:0.0.1"
+    }
+  ]
+}
+```
+
 ## Delete registry repository
 
 Delete a repository in registry.

lib/api/api.rb

@@ -161,6 +161,7 @@ module API
       mount ::API::Commits
       mount ::API::CommitStatuses
       mount ::API::ContainerRegistryEvent
+      mount ::API::ContainerRepositories
       mount ::API::DeployKeys
       mount ::API::DeployTokens
       mount ::API::Deployments

lib/api/container_repositories.rb

+# frozen_string_literal: true
+
+module API
+  class ContainerRepositories < ::API::Base
+    include Gitlab::Utils::StrongMemoize
+    helpers ::API::Helpers::PackagesHelpers
+
+    before { authenticate! }
+
+    namespace 'registry' do
+      params do
+        requires :id, type: String, desc: 'The ID of a project'
+      end
+      resource :repositories, requirements: { id: /[0-9]*/ } do
+        desc 'Get a container repository' do
+          detail 'This feature was introduced in GitLab 13.6.'
+          success Entities::ContainerRegistry::Repository
+        end
+        params do
+          optional :tags, type: Boolean, default: false, desc: 'Determines if tags should be included'
+          optional :tags_count, type: Boolean, default: false, desc: 'Determines if the tags count should be included'
+        end
+        get ':id' do
+          authorize!(:read_container_image, repository)
+
+          present repository, with: Entities::ContainerRegistry::Repository, tags: params[:tags], tags_count: params[:tags_count], user: current_user
+        end
+      end
+    end
+
+    helpers do
+      def repository
+        strong_memoize(:repository) do
+          ContainerRepository.find(params[:id])
+        end
+      end
+    end
+  end
+end

lib/api/entities/container_registry.rb

@@ -10,6 +10,8 @@ module API
       end
 
       class Repository < Grape::Entity
+        include ::API::Helpers::RelatedResourcesHelpers
+
         expose :id
         expose :name
         expose :path
@@ -19,6 +21,13 @@ module API
         expose :expiration_policy_started_at, as: :cleanup_policy_started_at
         expose :tags_count, if: -> (_, options) { options[:tags_count] }
         expose :tags, using: Tag, if: -> (_, options) { options[:tags] }
+        expose :delete_api_path, if: ->(object, options) { Ability.allowed?(options[:user], :admin_container_image, object) }
+
+        private
+
+        def delete_api_path
+          expose_url api_v4_projects_registry_repositories_path(repository_id: object.id, id: object.project_id)
+        end
       end
 
       class TagDetails < Tag

spec/requests/api/container_repositories_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe API::ContainerRepositories do
+  let_it_be(:project) { create(:project, :private) }
+  let_it_be(:reporter) { create(:user) }
+  let_it_be(:guest) { create(:user) }
+  let_it_be(:repository) { create(:container_repository, project: project) }
+
+  let(:users) do
+    {
+      anonymous: nil,
+      guest: guest,
+      reporter: reporter
+    }
+  end
+
+  let(:api_user) { reporter }
+
+  before do
+    project.add_reporter(reporter)
+    project.add_guest(guest)
+
+    stub_container_registry_config(enabled: true)
+  end
+
+  describe 'GET /registry/repositories/:id' do
+    let(:url) { "/registry/repositories/#{repository.id}" }
+
+    subject { get api(url, api_user) }
+
+    it_behaves_like 'rejected container repository access', :guest, :forbidden
+    it_behaves_like 'rejected container repository access', :anonymous, :unauthorized
+
+    context 'for allowed user' do
+      it 'returns a repository' do
+        subject
+
+        expect(json_response['id']).to eq(repository.id)
+        expect(response.body).not_to include('tags')
+      end
+
+      it 'returns a matching schema' do
+        subject
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response).to match_response_schema('registry/repository')
+      end
+
+      context 'with tags param' do
+        let(:url) { "/registry/repositories/#{repository.id}?tags=true" }
+
+        before do
+          stub_container_registry_tags(repository: repository.path, tags: %w(rootA latest), with_manifest: true)
+        end
+
+        it 'returns a repository and its tags' do
+          subject
+
+          expect(json_response['id']).to eq(repository.id)
+          expect(response.body).to include('tags')
+        end
+      end
+
+      context 'with tags_count param' do
+        let(:url) { "/registry/repositories/#{repository.id}?tags_count=true" }
+
+        before do
+          stub_container_registry_tags(repository: repository.path, tags: %w(rootA latest), with_manifest: true)
+        end
+
+        it 'returns a repository and its tags_count' do
+          subject
+
+          expect(response.body).to include('tags_count')
+          expect(json_response['tags_count']).to eq(2)
+        end
+      end
+    end
+
+    context 'with invalid repository id' do
+      let(:url) { "/registry/repositories/#{non_existing_record_id}" }
+
+      it_behaves_like 'returning response status', :not_found
+    end
+  end
+end