Add basic CI/CD functionality

This MR adds a basic CD/CD pipeline, which validates the top-level pipeline.cwl workflow with an example input.

.gitlab-ci.yml

@@ -6,7 +6,7 @@ workflow:
     - when: always
 
 stages:
-  - build
+  - prepare
   - test
 
 include:
@@ -14,14 +14,26 @@ include:
   - template: Security/Dependency-Scanning.gitlab-ci.yml
   - template: Security/Secret-Detection.gitlab-ci.yml
 
-build-image:
-  stage: build
-  image: docker:latest
-  before_script: 
-    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+build_ci_runner_image:
+  stage: prepare
+  image: docker
+  tags:
+    - dind
   script:
-    - docker build docker/ci-runner --tag $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG
+    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+    - |
+      if docker pull $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG; then
+        docker build --cache-from $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG --tag $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG docker/ci-runner
+      else
+        docker pull $CI_REGISTRY_IMAGE/ci-build-runner:latest || true
+        docker build --cache-from $CI_REGISTRY_IMAGE/ci-build-runner:latest --tag $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG docker/ci-runner
+      fi
     - docker push $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG  # push the image
+    - |
+      if [[ "$CI_COMMIT_BRANCH" == "$CI_DEFAULT_BRANCH" ]]; then
+        docker image tag $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG $CI_REGISTRY_IMAGE/ci-build-runner:latest
+        docker push $CI_REGISTRY_IMAGE/ci-build-runner:latest
+      fi
 
 sast:
   variables: