Merge branch 'fix-ci-login-to-registry' into 'master'

Fix the CI login to Container Registry (the gitlab-ci-token user)

## What does this MR do?

This fixes `docker login` not succeeding when trying to do CI login: `gitlab-ci-token with $CI_BUILD_TOKEN`.

cc @marin

See merge request !4236

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.8.0
+v 8.8.1 (unreleased)
+  - Fix MySQL compatibility in zero downtime migrations helpers
+  - Fix the CI login to Container Registry (the gitlab-ci-token user)
+
+v 8.8.0 (unreleased)
   - Implement GFM references for milestones (Alejandro Rodríguez)
   - Snippets tab under user profile. !4001 (Long Nguyen)
   - Fix error when using link to uploads in global snippets

app/controllers/jwt_controller.rb

@@ -36,7 +36,7 @@ class JwtController < ApplicationController
   end
 
   def authenticate_project(login, password)
-    if login == 'gitlab_ci_token'
+    if login == 'gitlab-ci-token'
       Project.find_by(builds_enabled: true, runners_token: password)
     end
   end

app/services/auth/container_registry_authentication_service.rb

@@ -6,7 +6,7 @@ module Auth
       return error('not found', 404) unless registry.enabled
 
       if params[:offline_token]
-        return error('unauthorized', 401) unless current_user
+        return error('unauthorized', 401) unless current_user || project
       else
         return error('forbidden', 403) unless scope
       end

spec/requests/jwt_controller_spec.rb

@@ -23,7 +23,7 @@ describe JwtController do
   context 'when using authorized request' do
     context 'using CI token' do
       let(:project) { create(:empty_project, runners_token: 'token', builds_enabled: builds_enabled) }
-      let(:headers) { { authorization: credentials('gitlab_ci_token', project.runners_token) } }
+      let(:headers) { { authorization: credentials('gitlab-ci-token', project.runners_token) } }
 
       subject! { get '/jwt/auth', parameters, headers }
 

spec/services/auth/container_registry_authentication_service_spec.rb

@@ -127,12 +127,12 @@ describe Auth::ContainerRegistryAuthenticationService, services: true do
   context 'project authorization' do
     let(:current_project) { create(:empty_project) }
 
-    context 'disallow to use offline_token' do
+    context 'allow to use offline_token' do
       let(:current_params) do
         { offline_token: true }
       end
 
-      it_behaves_like 'an unauthorized'
+      it_behaves_like 'an authenticated'
     end
 
     context 'allow to pull and push images' do