Multiple pipeline support for Build status

This allows user to specify the pipeline ID
when several pipelines has been triggered
on the same branch and commit.
Signed-off-by: Gaetan Semet <gaetan.semet@renault.com>

changelogs/unreleased/21671-multiple-pipeline-status-api.yml

+---
+title: Multiple pipeline support for Commit status
+merge_request: 21671
+author: Gaetan Semet
+type: changed

doc/api/commits.md

@@ -581,6 +581,7 @@ POST /projects/:id/statuses/:sha
 | `target_url` |  string  | no  | The target URL to associate with this status
 | `description` | string  | no  | The short description of the status
 | `coverage` | float  | no    | The total code coverage
+| `pipeline_id` |  integer  | no  | The id of the pipeline to set status. Use in case of several pipeline on same sha.
 
 ```bash
 curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/projects/17/statuses/18f3e63d05582537db6d183d9d557be09e1f90c8?state=success"

lib/api/commit_statuses.rb

@@ -52,6 +52,7 @@ module API
         optional :name,        type: String,  desc: 'A string label to differentiate this status from the status of other systems. Default: "default"'
         optional :context,     type: String,  desc: 'A string label to differentiate this status from the status of other systems. Default: "default"'
         optional :coverage,    type: Float,   desc: 'The total code coverage'
+        optional :pipeline_id, type: Integer, desc: 'An existing pipeline id, when multiple pipelines on the same commit sha have been triggered'
       end
       # rubocop: disable CodeReuse/ActiveRecord
       post ':id/statuses/:sha' do
@@ -72,8 +73,12 @@ module API
         not_found! 'References for commit' unless ref
 
         name = params[:name] || params[:context] || 'default'
+        pipeline = if params[:pipeline_id]
+                     @project.ci_pipelines.find_by(id: params[:pipeline_id])
+                   else
+                     @project.pipeline_for(ref, commit.sha)
+                   end
 
-        pipeline = @project.pipeline_for(ref, commit.sha)
         unless pipeline
           pipeline = @project.ci_pipelines.create!(
             source: :external,