Add instance-level maven endpoint for download

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

doc/user/project/packages/maven_repository.md

@@ -119,6 +119,31 @@ on the home page of your project.
 If you have a self-hosted GitLab installation, replace `gitlab.com` with your
 domain name.
 
+## Instance level Maven endpoint
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/8274) in GitLab Premium 11.6.
+
+If you rely on many packages, it might be inefficient to include the `repository` section 
+with a unique URL for each package. Instead, you can use the instance level endpoint for 
+all maven packages stored in GitLab. Only packages you have access to 
+will be available for download. Here's how the relevant `repository` section of 
+your `pom.xml` would look like:
+
+```xml
+<repositories>
+  <repository>
+    <id>gitlab-maven</id>
+    <url>https://gitlab.com/api/v4/packages/maven</url>
+  </repository>
+</repositories>
+```
+
+If you have a self-hosted GitLab installation, replace `gitlab.com` with your
+domain name.
+
+You still need a project specific URL for uploading a package 
+in the `distributionManagement` section.
+
 ## Uploading packages
 
 Once you have set up the [authorization](#authorizing-with-the-gitlab-maven-repository)

ee/app/finders/packages/maven_package_finder.rb

 # frozen_string_literal: true
 class Packages::MavenPackageFinder
-  attr_reader :project, :path
+  attr_reader :path, :project
 
-  def initialize(project, path)
-    @project = project
+  def initialize(path, project = nil)
     @path = path
+    @project = project
   end
 
   def execute
@@ -17,9 +17,17 @@ class Packages::MavenPackageFinder
 
   private
 
+  def scope
+    if project
+      project.packages
+    else
+      ::Packages::Package.all
+    end
+  end
+
   # rubocop: disable CodeReuse/ActiveRecord
   def packages
-    project.packages.joins(:maven_metadatum)
+    scope.joins(:maven_metadatum)
       .where(packages_maven_metadata: { path: path })
   end
   # rubocop: enable CodeReuse/ActiveRecord

ee/app/services/packages/find_or_create_maven_package_service.rb

@@ -5,7 +5,7 @@ module Packages
 
     def execute
       package = ::Packages::MavenPackageFinder
-        .new(project, params[:path]).execute
+        .new(params[:path], project).execute
 
       unless package
         if params[:file_name] == MAVEN_METADATA_FILE

ee/changelogs/unreleased/7769-instance-level-maven-endpoint.yml

+---
+title: Add an instance-level endpoint for downloading maven packages
+merge_request: 8274
+author:
+type: added

ee/lib/api/maven_packages.rb

@@ -12,7 +12,6 @@ module API
     before do
       require_packages_enabled!
       authenticate_non_get!
-      authorize_packages_feature!
     end
 
     helpers do
@@ -54,10 +53,44 @@ module API
       end
     end
 
+    desc 'Download the maven package file at instance level' do
+      detail 'This feature was introduced in GitLab 11.6'
+    end
+    params do
+      requires :path, type: String, desc: 'Package path'
+      requires :file_name, type: String, desc: 'Package file name'
+    end
+    route_setting :authentication, job_token_allowed: true
+    get 'packages/maven/*path/:file_name', requirements: MAVEN_ENDPOINT_REQUIREMENTS do
+      file_name, format = extract_format(params[:file_name])
+
+      package = ::Packages::MavenPackageFinder.new(params[:path]).execute!
+
+      forbidden! unless package.project.feature_available?(:packages)
+
+      authorize!(:read_package, package.project)
+
+      package_file = ::Packages::PackageFileFinder
+        .new(package, file_name).execute!
+
+      case format
+      when 'md5'
+        package_file.file_md5
+      when 'sha1'
+        package_file.file_sha1
+      when nil
+        present_carrierwave_file!(package_file.file)
+      end
+    end
+
     params do
       requires :id, type: String, desc: 'The ID of a project'
     end
     resource :projects, requirements: API::PROJECT_ENDPOINT_REQUIREMENTS do
+      before do
+        authorize_packages_feature!
+      end
+
       desc 'Download the maven package file' do
         detail 'This feature was introduced in GitLab 11.3'
       end
@@ -72,7 +105,7 @@ module API
         file_name, format = extract_format(params[:file_name])
 
         package = ::Packages::MavenPackageFinder
-          .new(user_project, params[:path]).execute!
+          .new(params[:path], user_project).execute!
 
         package_file = ::Packages::PackageFileFinder
           .new(package, file_name).execute!

ee/spec/finders/packages/maven_package_finder_spec.rb

@@ -6,16 +6,32 @@ describe Packages::MavenPackageFinder do
   let(:package) { create(:maven_package, project: project) }
 
   describe '#execute!' do
-    it 'returns a package' do
-      finder = described_class.new(project, package.maven_metadatum.path)
+    context 'within the project' do
+      it 'returns a package' do
+        finder = described_class.new(package.maven_metadatum.path, project)
 
-      expect(finder.execute!).to eq(package)
+        expect(finder.execute!).to eq(package)
+      end
+
+      it 'raises an error' do
+        finder = described_class.new('com/example/my-app/1.0-SNAPSHOT', project)
+
+        expect { finder.execute! }.to raise_error(ActiveRecord::RecordNotFound)
+      end
     end
 
-    it 'raises an error' do
-      finder = described_class.new(project, 'com/example/my-app/1.0-SNAPSHOT')
+    context 'across all projects' do
+      it 'returns a package' do
+        finder = described_class.new(package.maven_metadatum.path)
+
+        expect(finder.execute!).to eq(package)
+      end
+
+      it 'raises an error' do
+        finder = described_class.new('com/example/my-app/1.0-SNAPSHOT')
 
-      expect { finder.execute! }.to raise_error(ActiveRecord::RecordNotFound)
+        expect { finder.execute! }.to raise_error(ActiveRecord::RecordNotFound)
+      end
     end
   end
 end

ee/spec/requests/api/maven_packages_spec.rb

@@ -15,6 +15,106 @@ describe API::MavenPackages do
     stub_licensed_features(packages: true)
   end
 
+  describe 'GET /api/v4/packages/maven/*path/:file_name' do
+    let(:package) { create(:maven_package, project: project) }
+    let(:maven_metadatum) { package.maven_metadatum }
+    let(:package_file_xml) { package.package_files.find_by(file_type: 'xml') }
+
+    context 'a public project' do
+      it 'returns the file' do
+        download_file(package_file_xml.file_name)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(response.content_type.to_s).to eq('application/octet-stream')
+      end
+
+      it 'returns sha1 of the file' do
+        download_file(package_file_xml.file_name + '.sha1')
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(response.content_type.to_s).to eq('text/plain')
+        expect(response.body).to eq(package_file_xml.file_sha1)
+      end
+    end
+
+    context 'internal project' do
+      before do
+        project.team.truncate
+        project.update!(visibility_level: Gitlab::VisibilityLevel::INTERNAL)
+      end
+
+      it 'returns the file' do
+        download_file_with_token(package_file_xml.file_name)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(response.content_type.to_s).to eq('application/octet-stream')
+      end
+
+      it 'denies download when no private token' do
+        download_file(package_file_xml.file_name)
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+
+      it 'allows download with job token' do
+        download_file(package_file_xml.file_name, job_token: job.token)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(response.content_type.to_s).to eq('application/octet-stream')
+      end
+    end
+
+    context 'private project' do
+      before do
+        project.update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
+      end
+
+      it 'returns the file' do
+        download_file_with_token(package_file_xml.file_name)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(response.content_type.to_s).to eq('application/octet-stream')
+      end
+
+      it 'denies download when not enough permissions' do
+        project.add_guest(user)
+
+        download_file_with_token(package_file_xml.file_name)
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+
+      it 'denies download when no private token' do
+        download_file(package_file_xml.file_name)
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+
+      it 'allows download with job token' do
+        download_file(package_file_xml.file_name, job_token: job.token)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(response.content_type.to_s).to eq('application/octet-stream')
+      end
+    end
+
+    it 'rejects request if feature is not in the license' do
+      stub_licensed_features(packages: false)
+
+      download_file(package_file_xml.file_name)
+
+      expect(response).to have_gitlab_http_status(403)
+    end
+
+    def download_file(file_name, params = {}, request_headers = headers)
+      get api("/packages/maven/#{maven_metadatum.path}/#{file_name}"), params, request_headers
+    end
+
+    def download_file_with_token(file_name, params = {}, request_headers = headers_with_token)
+      download_file(file_name, params, request_headers)
+    end
+  end
+
   describe 'GET /api/v4/projects/:id/packages/maven/*path/:file_name' do
     let(:package) { create(:maven_package, project: project) }
     let(:maven_metadatum) { package.maven_metadatum }