Work on Go module proxy

- Call package authorization helpers
- Add change long entry
- Fix rubocop violations
- Add basic documentation

doc/administration/packages/index.md

@@ -13,6 +13,7 @@ The Packages feature allows GitLab to act as a repository for the following:
 | [Conan Repository](../../user/packages/conan_repository/index.md) | The GitLab Conan Repository enables every project in GitLab to have its own space to store [Conan](https://conan.io/) packages. | 12.4+ |
 | [Maven Repository](../../user/packages/maven_repository/index.md) | The GitLab Maven Repository enables every project in GitLab to have its own space to store [Maven](https://maven.apache.org/) packages. | 11.3+ |
 | [NPM Registry](../../user/packages/npm_registry/index.md)   | The GitLab NPM Registry enables every project in GitLab to have its own space to store [NPM](https://www.npmjs.com/) packages. | 11.7+ |
+| [Go Proxy](../../user/packages/go_proxy/index.md) | The GitLab Go Proxy enables every project in GitLab to be fetched via the [Go proxy protocol](https://proxy.golang.org/). | ??.??+ |
 
 Don't you see your package management system supported yet?
 Please consider contributing

doc/user/packages/go_proxy/index.md

+# GitLab Go Proxy **(PREMIUM)**
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/27376) in [GitLab Premium](https://about.gitlab.com/pricing/) ??.??.
+
+The GitLab Go Proxy implements the Go proxy protocol.
+
+NOTE: **Note:**
+GitLab does not (yet) display Go modules in the **Packages** section of a project.
+Only the Go proxy protocol is supported at this time.
+
+## Enabling the Go proxy
+
+NOTE: **Note:**
+This option is available only if your GitLab administrator has
+[enabled support for the Package Registry](../../../administration/packages/index.md). **(PREMIUM ONLY)**
+
+After the Package Registry is enabled, it will be available for all new projects
+by default. To enable it for existing projects, or if you want to disable it:
+
+1. Navigate to your project's **Settings > General > Permissions**.
+1. Find the Packages feature and enable or disable it.
+1. Click on **Save changes** for the changes to take effect.
+
+You should then be able to see the **Packages** section on the left sidebar.

ee/app/models/packages/go_module.rb

 # frozen_string_literal: true
 
-class Packages::GoModule #< ApplicationRecord
+class Packages::GoModule
   SEMVER_TAG_REGEX = Regexp.new("^#{::Packages::GoModuleVersion::SEMVER_REGEX.source}$").freeze
 
   # belongs_to :project
 
-  attr_reader :project, :name, :path, :versions
+  attr_reader :project, :name, :path
 
   def initialize(project, name)
     @project = project
@@ -15,17 +15,17 @@ class Packages::GoModule #< ApplicationRecord
       if @name == package_base
         ''
       elsif @name.start_with?(package_base + '/')
-        @name[(package_base.length+1)..]
+        @name[(package_base.length + 1)..]
       else
         nil
       end
   end
 
   def versions
-    @versions ||= project.repository.tags.
-      filter { |tag| SEMVER_TAG_REGEX.match?(tag.name) && !tag.dereferenced_target.nil? }.
-      map    { |tag| ::Packages::GoModuleVersion.new self, tag }.
-      filter { |ver| ver.valid? }
+    @versions ||= project.repository.tags
+      .filter { |tag| SEMVER_TAG_REGEX.match?(tag.name) && !tag.dereferenced_target.nil? }
+      .map    { |tag| ::Packages::GoModuleVersion.new self, tag }
+      .filter { |ver| ver.valid? }
   end
 
   def find_version(name)

ee/app/models/packages/go_module_version.rb

 # frozen_string_literal: true
 
-class Packages::GoModuleVersion #< ApplicationRecord
+class Packages::GoModuleVersion
   SEMVER_REGEX = /v(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-([-.A-Z0-9]+))?(?:\+([-.A-Z0-9]+))?/i.freeze
   VERSION_SUFFIX_REGEX = /\/v([1-9]\d*)$/i.freeze
 

ee/app/presenters/packages/go/module_version_presenter.rb

@@ -16,4 +16,4 @@ module Packages
       end
     end
   end
-end
\ No newline at end of file
+end

ee/changelogs/unreleased/27376-go-package-mvc.yml

+---
+title: Implement Go module proxy MVC (package manager for Go)
+merge_request: 27746
+author: Ethan Reesor
+type: added

ee/lib/api/go_proxy.rb

@@ -3,7 +3,9 @@ module API
   class GoProxy < Grape::API
     helpers ::API::Helpers::PackagesHelpers
 
-    MODULE_VERSION_REQUIREMENTS = { :module_version => ::Packages::GoModuleVersion::SEMVER_REGEX }
+    MODULE_VERSION_REQUIREMENTS = { module_version: ::Packages::GoModuleVersion::SEMVER_REGEX }.freeze
+
+    before { require_packages_enabled! }
 
     helpers do
       def find_module
@@ -23,6 +25,11 @@ module API
       requires :module_name, type: String, desc: 'Module name'
     end
     resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      before do
+        authorize_read_package!
+        authorize_packages_feature!
+      end
+
       namespace ':id/packages/go/*module_name/@v' do
         desc 'Get all tagged versions for a given Go module' do
           detail 'See `go help goproxy`, GET $GOPROXY/<module>/@v/list'
@@ -41,7 +48,7 @@ module API
         params do
           requires :module_version, type: String, desc: 'Module version'
         end
-        get ':module_version.info', :requirements => MODULE_VERSION_REQUIREMENTS do
+        get ':module_version.info', requirements: MODULE_VERSION_REQUIREMENTS do
           mod = find_module
 
           ver = mod.find_version params[:module_version]
@@ -56,7 +63,7 @@ module API
         params do
           requires :module_version, type: String, desc: 'Module version'
         end
-        get ':module_version.mod', :requirements => MODULE_VERSION_REQUIREMENTS do
+        get ':module_version.mod', requirements: MODULE_VERSION_REQUIREMENTS do
           mod = find_module
 
           ver = mod.find_version params[:module_version]
@@ -72,7 +79,7 @@ module API
         params do
           requires :module_version, type: String, desc: 'Module version'
         end
-        get ':module_version.zip', :requirements => MODULE_VERSION_REQUIREMENTS do
+        get ':module_version.zip', requirements: MODULE_VERSION_REQUIREMENTS do
           mod = find_module
 
           ver = mod.find_version params[:module_version]
@@ -95,4 +102,4 @@ module API
       end
     end
   end
-end
\ No newline at end of file
+end

ee/lib/ee/api/entities/go_module_version.rb

 # frozen_string_literal: true
 
 module EE
-    module API
-      module Entities
-        class GoModuleVersion < Grape::Entity
-          expose :name, as: 'Version'
-          expose :time, as: 'Time'
-        end
+  module API
+    module Entities
+      class GoModuleVersion < Grape::Entity
+        expose :name, as: 'Version'
+        expose :time, as: 'Time'
       end
     end
   end
+end