Include source in composer json payload

Include git source as part of the
Composer version spec json

app/models/packages/package.rb

@@ -29,6 +29,7 @@ class Packages::Package < ApplicationRecord
 
   delegate :recipe, :recipe_path, to: :conan_metadatum, prefix: :conan
   delegate :codename, :suite, to: :debian_distribution, prefix: :debian_distribution
+  delegate :target_sha, to: :composer_metadatum, prefix: :composer
 
   validates :project, presence: true
   validates :name, presence: true

changelogs/unreleased/247531-composer-source-jsonn.yml

+---
+title: Support for --prefer-source option for Composer registry
+merge_request: 56693
+author:
+type: changed

doc/user/packages/composer_repository/index.md

@@ -274,8 +274,21 @@ To install a package:
    composer update
    ```
 
+   Or to install the single package:
+
+   ```shell
+   composer req <package-name>:<package-version>
+   ```
+
    If successful, you should see output indicating that the package installed successfully.
 
+   You can also install from source (by pulling the Git repository directly) using the
+   `--prefer-source` option:
+
+   ```shell
+   composer update --prefer-source
+   ```
+
 WARNING:
 Never commit the `auth.json` file to your repository. To install packages from a CI/CD job,
 consider using the [`composer config`](https://getcomposer.org/doc/articles/handling-private-packages.md#satis) tool with your personal access token

lib/gitlab/composer/version_index.rb

@@ -28,20 +28,34 @@ module Gitlab
       def package_metadata(package)
         json = package.composer_metadatum.composer_json
 
-        json.merge('dist' => package_dist(package), 'uid' => package.id, 'version' => package.version)
+        json.merge(
+          'dist' => package_dist(package),
+          'source' => package_source(package),
+          'uid' => package.id,
+          'version' => package.version
+        )
       end
 
       def package_dist(package)
-        sha = package.composer_metadatum.target_sha
         archive_api_path = api_v4_projects_packages_composer_archives_package_name_path({ id: package.project_id, package_name: package.name, format: '.zip' }, true)
 
         {
           'type' => 'zip',
-          'url' => expose_url(archive_api_path) + "?sha=#{sha}",
-          'reference' => sha,
+          'url' => expose_url(archive_api_path) + "?sha=#{package.composer_target_sha}",
+          'reference' => package.composer_target_sha,
           'shasum' => ''
         }
       end
+
+      def package_source(package)
+        git_url = package.project.http_url_to_repo
+
+        {
+          'type' => 'git',
+          'url' => git_url,
+          'reference' => package.composer_target_sha
+        }
+      end
     end
   end
 end

spec/lib/gitlab/composer/version_index_spec.rb

@@ -27,6 +27,11 @@ RSpec.describe Gitlab::Composer::VersionIndex do
           'type' => 'zip',
           'url' => "http://localhost/api/v4/projects/#{project.id}/packages/composer/archives/#{package.name}.zip?sha=#{branch.target}"
         },
+        'source' => {
+          'reference' => branch.target,
+          'type' => 'git',
+          'url' => project.http_url_to_repo
+        },
         'name' => package.name,
         'uid' => package.id,
         'version' => package.version

spec/presenters/packages/composer/packages_presenter_spec.rb

@@ -9,8 +9,8 @@ RSpec.describe ::Packages::Composer::PackagesPresenter do
   let_it_be(:json) { { 'name' => package_name } }
   let_it_be(:group) { create(:group) }
   let_it_be(:project) { create(:project, :custom_repo, files: { 'composer.json' => json.to_json }, group: group) }
-  let_it_be(:package1) { create(:composer_package, :with_metadatum, project: project, name: package_name, version: '1.0.0', json: json) }
-  let_it_be(:package2) { create(:composer_package, :with_metadatum, project: project, name: package_name, version: '2.0.0', json: json) }
+  let!(:package1) { create(:composer_package, :with_metadatum, project: project, name: package_name, version: '1.0.0', json: json) }
+  let!(:package2) { create(:composer_package, :with_metadatum, project: project, name: package_name, version: '2.0.0', json: json) }
 
   let(:branch) { project.repository.find_branch('master') }
 
@@ -28,6 +28,11 @@ RSpec.describe ::Packages::Composer::PackagesPresenter do
           'type' => 'zip',
           'url' => "http://localhost/api/v4/projects/#{project.id}/packages/composer/archives/#{package.name}.zip?sha=#{branch.target}"
         },
+        'source' => {
+          'reference' => branch.target,
+          'type' => 'git',
+          'url' => "http://localhost/#{group.path}/#{project.path}.git"
+        },
         'name' => package.name,
         'uid' => package.id,
         'version' => package.version