Add changes required since GitLab 12.5

.gitlab-ci.yml

@@ -2,12 +2,12 @@ build_docker:
   only:
     - pushes
     - merge_requests
-  except:
-    - triggers
   tags:
     - docker-privileged
-    - docker-machine
-  image: docker:latest
+  image: docker:19.03.1
+  services:
+  # To obtain a Docker daemon, request a Docker-in-Docker service
+  - docker:19.03.1-dind
   before_script:
     - docker login -u $CI_REGISTRY_USER -p $CI_BUILD_TOKEN $CI_REGISTRY
     # Need to start the automounter for CVMFS:
@@ -22,3 +22,4 @@ build_docker:
   variables:
     FROM: clelange/cc7-cms # Override the image specified in the Dockerfile
     TO: ${CI_REGISTRY_IMAGE}:${CI_COMMIT_SHORT_SHA}
+    DOCKER_TLS_CERTDIR: "/certs"