CE port for pipelines for external pull requestsce-detect-github-pull-requests

Detect if pipeline runs for a GitHub pull request

When using a mirror for CI/CD only we register a pull_request
webhook. When a pull_request webhook is received, if the
source branch SHA matches the actual head of the branch in the
repository we create immediately a new pipeline for the
external pull request. Otherwise we store the
pull request info for when the push webhook is received.

When using "only/except: external_pull_requests" we can detect
if the pipeline has a open pull request on GitHub and create or
not the job based on that.

2 files changed, 33 insertions, 1 deletions

diff --git a/app/services/ci/create_pipeline_service.rb b/app/services/ci/create_pipeline_service.rb
index 29317f1176e..94b581a0eef 100644
--- a/app/services/ci/create_pipeline_service.rb
+++ b/app/services/ci/create_pipeline_service.rb
@@ -18,7 +18,8 @@ module Ci
                 Gitlab::Ci::Pipeline::Chain::Limit::Activity,
                 Gitlab::Ci::Pipeline::Chain::Limit::JobActivity].freeze
 
-    def execute(source, ignore_skip_ci: false, save_on_errors: true, trigger_request: nil, schedule: nil, merge_request: nil, **options, &block)
+    # rubocop: disable Metrics/ParameterLists
+    def execute(source, ignore_skip_ci: false, save_on_errors: true, trigger_request: nil, schedule: nil, merge_request: nil, external_pull_request: nil, **options, &block)
       @pipeline = Ci::Pipeline.new
 
       command = Gitlab::Ci::Pipeline::Chain::Command.new(
@@ -32,6 +33,7 @@ module Ci
         trigger_request: trigger_request,
         schedule: schedule,
         merge_request: merge_request,
+        external_pull_request: external_pull_request,
         ignore_skip_ci: ignore_skip_ci,
         save_incompleted: save_on_errors,
         seeds_block: block,
@@ -62,6 +64,7 @@ module Ci
 
       pipeline
     end
+    # rubocop: enable Metrics/ParameterLists
 
     def execute!(*args, &block)
       execute(*args, &block).tap do |pipeline|
diff --git a/app/services/external_pull_requests/create_pipeline_service.rb b/app/services/external_pull_requests/create_pipeline_service.rb
new file mode 100644
index 00000000000..36411465ff1
--- /dev/null
+++ b/app/services/external_pull_requests/create_pipeline_service.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+# This service is responsible for creating a pipeline for a given
+# ExternalPullRequest coming from other providers such as GitHub.
+
+module ExternalPullRequests
+  class CreatePipelineService < BaseService
+    def execute(pull_request)
+      return unless pull_request.open? && pull_request.actual_branch_head?
+
+      create_pipeline_for(pull_request)
+    end
+
+    private
+
+    def create_pipeline_for(pull_request)
+      Ci::CreatePipelineService.new(project, current_user, create_params(pull_request))
+        .execute(:external_pull_request_event, external_pull_request: pull_request)
+    end
+
+    def create_params(pull_request)
+      {
+        ref: pull_request.source_ref,
+        source_sha: pull_request.source_sha,
+        target_sha: pull_request.target_sha
+      }
+    end
+  end
+end