Introduce ENV var for source/target repository

In case of a external pull request pipeline, this will now include
information about the source and the target repositories in new ENV
vars:
- CI_EXTERNAL_PULL_REQUEST_SOURCE_REPOSITORY
- CI_EXTERNAL_PULL_REQUEST_TARGET_REPOSITORY

This information is useful for users who need to influence external
repositories based on the result of a Gitlab pipeline.

app/models/external_pull_request.rb

@@ -63,6 +63,8 @@ class ExternalPullRequest < ApplicationRecord
   def predefined_variables
     Gitlab::Ci::Variables::Collection.new.tap do |variables|
       variables.append(key: 'CI_EXTERNAL_PULL_REQUEST_IID', value: pull_request_iid.to_s)
+      variables.append(key: 'CI_EXTERNAL_PULL_REQUEST_SOURCE_REPOSITORY', value: source_repository)
+      variables.append(key: 'CI_EXTERNAL_PULL_REQUEST_TARGET_REPOSITORY', value: target_repository)
       variables.append(key: 'CI_EXTERNAL_PULL_REQUEST_SOURCE_BRANCH_SHA', value: source_sha)
       variables.append(key: 'CI_EXTERNAL_PULL_REQUEST_TARGET_BRANCH_SHA', value: target_sha)
       variables.append(key: 'CI_EXTERNAL_PULL_REQUEST_SOURCE_BRANCH_NAME', value: source_branch)

changelogs/unreleased/223831-pr-repository-env-var.yml

+---
+title: "Add ENV vars that expose source and target repository for CI Pipelines that run on an External Pull Requests."
+merge_request: 37616
+author: Rafael Dohms @rdohms
+type: added

doc/ci/variables/predefined_variables.md

@@ -56,6 +56,8 @@ Kubernetes-specific environment variables are detailed in the
 | `CI_ENVIRONMENT_SLUG`                         | 8.15   | all    | A simplified version of the environment name, suitable for inclusion in DNS, URLs, Kubernetes labels, etc. Only present if [`environment:name`](../yaml/README.md#environmentname) is set.                                                                                                                                                                 |
 | `CI_ENVIRONMENT_URL`                          | 9.3    | all    | The URL of the environment for this job. Only present if [`environment:url`](../yaml/README.md#environmenturl) is set.                                                                                                                                                                                                                                     |
 | `CI_EXTERNAL_PULL_REQUEST_IID`                | 12.3   | all    | Pull Request ID from GitHub if the [pipelines are for external pull requests](../ci_cd_for_external_repos/index.md#pipelines-for-external-pull-requests). Available only if `only: [external_pull_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the pull request is open.                                                                                                         |
+| `CI_EXTERNAL_PULL_REQUEST_SOURCE_REPOSITORY`  | 13.3   | all    | The source repository name of the pull request if [the pipelines are for external pull requests](../ci_cd_for_external_repos/index.md#pipelines-for-external-pull-requests). Available only if `only: [external_pull_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the pull request is open.                                                                                          |
+| `CI_EXTERNAL_PULL_REQUEST_TARGET_REPOSITORY`  | 13.3   | all    | The target repository name of the pull request if [the pipelines are for external pull requests](../ci_cd_for_external_repos/index.md#pipelines-for-external-pull-requests). Available only if `only: [external_pull_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the pull request is open.                                                                                          |
 | `CI_EXTERNAL_PULL_REQUEST_SOURCE_BRANCH_NAME` | 12.3   | all    | The source branch name of the pull request if [the pipelines are for external pull requests](../ci_cd_for_external_repos/index.md#pipelines-for-external-pull-requests). Available only if `only: [external_pull_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the pull request is open.                                                                                          |
 | `CI_EXTERNAL_PULL_REQUEST_SOURCE_BRANCH_SHA`  | 12.3   | all    | The HEAD SHA of the source branch of the pull request if [the pipelines are for external pull requests](../ci_cd_for_external_repos/index.md#pipelines-for-external-pull-requests). Available only if `only: [external_pull_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the pull request is open.                                                                               |
 | `CI_EXTERNAL_PULL_REQUEST_TARGET_BRANCH_NAME` | 12.3   | all    | The target branch name of the pull request if [the pipelines are for external pull requests](../ci_cd_for_external_repos/index.md#pipelines-for-external-pull-requests). Available only if `only: [external_pull_requests]` or [`rules`](../yaml/README.md#rules) syntax is used and the pull request is open.                                                                                          |

spec/models/ci/pipeline_spec.rb

@@ -813,6 +813,8 @@ RSpec.describe Ci::Pipeline, :mailer do
         expect(subject.to_hash)
           .to include(
             'CI_EXTERNAL_PULL_REQUEST_IID' => pull_request.pull_request_iid.to_s,
+            'CI_EXTERNAL_PULL_REQUEST_SOURCE_REPOSITORY' => pull_request.source_repository,
+            'CI_EXTERNAL_PULL_REQUEST_TARGET_REPOSITORY' => pull_request.target_repository,
             'CI_EXTERNAL_PULL_REQUEST_SOURCE_BRANCH_SHA' => pull_request.source_sha,
             'CI_EXTERNAL_PULL_REQUEST_TARGET_BRANCH_SHA' => pull_request.target_sha,
             'CI_EXTERNAL_PULL_REQUEST_SOURCE_BRANCH_NAME' => pull_request.source_branch,