CE port for pipelines for external 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.

1 files changed, 15 insertions, 0 deletions

diff --git a/db/migrate/20190830075508_add_external_pull_request_id_to_ci_pipelines.rb b/db/migrate/20190830075508_add_external_pull_request_id_to_ci_pipelines.rb
new file mode 100644
index 00000000000..5abf56742b1
--- /dev/null
+++ b/db/migrate/20190830075508_add_external_pull_request_id_to_ci_pipelines.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class AddExternalPullRequestIdToCiPipelines < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    add_column :ci_pipelines, :external_pull_request_id, :bigint
+  end
+
+  def down
+    remove_column :ci_pipelines, :external_pull_request_id
+  end
+end