ci/external-mr: add checkout external MR option

This patch adds the possibility to run `deployment-pipeline`
checking out an external public repository.

Signed-off-by: Leandro Belli <leandro.belli@arm.com>
Change-Id: I9ce6d3ec62588c693fd011e7846702193e8472fd

.gitlab/.gitlab-ci.yml

@@ -14,6 +14,17 @@ variables:
       - "weekly-pipeline"
     description: "The CI pipeline to run"
 
+  FETCH_PUBLIC_MR:
+    value : "false"
+    options:
+      - "false"
+      - "true"
+    description: "Fetch branch from public MR"
+
+  FETCH_PUBLIC_MR_NUMBER:
+    description: "MR number to fetch"
+
+
 include:
   - local: .gitlab/pipelines/deployment-pipeline.yml
     rules:

.gitlab/pipelines/deployment-pipeline.yml

@@ -6,52 +6,97 @@
 #
 
 stages:
+  - test-workspace
   - linting
   - static-analysis
   - unit-testing
   - build
   - scmi-test
 
 include:
+  - local: .gitlab/templates/setup-workspace.yml
   - local: .gitlab/templates/linting.yml
   - local: .gitlab/templates/static-analysis.yml
   - local: .gitlab/templates/unit-test.yml
   - local: .gitlab/templates/build-test.yml
   - local: .gitlab/templates/scmi-test.yml
   - local: .gitlab/templates/coverity-test.yml
 
+
+pull-mr:
+  stage: .pre
+  extends: .pull-mr
+
 check-lint:
-  extends: .check-lint
+  extends:
+    - .check-lint
+    - .git-strategy-on-mr
   stage: linting
+  dependencies:
+    - pull-mr
 
 check-copyright:
-  extends: .check-copyright
+  before_script:
+    - ls .gitlab/templates
+  extends:
+    - .check-copyright
+    - .git-strategy-on-mr
   stage: linting
+  dependencies:
+    - pull-mr
 
 check-style:
-  extends: .check-style
+  extends:
+    - .check-style
+    - .git-strategy-on-mr
   stage: linting
+  dependencies:
+    - pull-mr
 
 banned-api:
-  extends: .banned-api
+  extends:
+    - .banned-api
+    - .git-strategy-on-mr
   stage: static-analysis
+  dependencies:
+    - pull-mr
 
 coverity-test:
   stage: static-analysis
-  extends: .coverity-test
+  extends:
+    - .coverity-test
+    - .git-strategy-on-mr
+  dependencies:
+    - pull-mr
 
 check-fwk:
-  extends: .check-fwk
+  extends:
+    - .check-fwk
+    - .git-strategy-on-mr
   stage: unit-testing
+  dependencies:
+    - pull-mr
 
 check-modules:
-  extends: .check-modules
+  extends:
+    - .check-modules
+    - .git-strategy-on-mr
   stage: unit-testing
+  dependencies:
+    - pull-mr
 
 build-products:
-  extends: .build-products
+  extends:
+    - .build-products
+    - .git-strategy-on-mr
   stage: build
+  dependencies:
+    - pull-mr
 
 scmi-test:
-  extends: .scmi-test
+  extends:
+    - .scmi-test
+    - .git-strategy-on-mr
   stage: scmi-test
+  dependencies:
+    - pull-mr

.gitlab/templates/setup-workspace.yml

@@ -0,0 +1,50 @@
+#
+# Arm SCP/MCP Software
+# Copyright (c) 2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+
+.pull-mr:
+  image: ${CI_REGISTRY_IMAGE}/ci-base:latest
+  variables:
+    GIT_STRATEGY: clone
+    GIT_CHECKOUT: "false"
+  script:
+    - |
+      MR_INFO=$(curl --fail \
+        "${PUBLIC_REPO_API_URL}/merge_requests/${FETCH_PUBLIC_MR_NUMBER}")
+      SCP_REFSPEC=$(printf "%s" "$MR_INFO" | jq -r .source_branch)
+
+      git fetch $PUBLIC_REPO_URL $SCP_REFSPEC
+
+      echo "Fetched commit:"
+      git rev-list --format=%B --max-count=1 FETCH_HEAD
+      git checkout FETCH_HEAD
+      git submodule update --init --recursive --depth 1
+
+      git fetch origin main
+      CI_MERGE_REQUEST_DIFF_BASE_SHA=$(git merge-base FETCH_HEAD origin/main)
+
+      # Save ENV variables
+      mkdir -p .env
+
+      echo "CI_MERGE_REQUEST_DIFF_BASE_SHA=$CI_MERGE_REQUEST_DIFF_BASE_SHA" \
+        >> .env/workspace.env
+  artifacts:
+    reports:
+      dotenv: .env/workspace.env
+    paths:
+      - . # Save workspace
+  rules:
+    - if: $FETCH_PUBLIC_MR == "true"
+
+.git-strategy-on-mr:
+  rules:
+    - if: $FETCH_PUBLIC_MR == "true"
+      variables:
+        GIT_STRATEGY: none
+    - if: $FETCH_PUBLIC_MR == "false"
+      variables:
+        GIT_STRATEGY: fetch