dind: use network address for docker.

.gitlab-ci.yml

@@ -25,8 +25,15 @@ variables:
   ## (Optional) More verbose output from pipeline
   #CI_DEBUG_TRACE: "true"
 
+  # When using dind service, we need to instruct docker to talk with
+  # the daemon started inside of the service. The daemon is available
+  # with a network connection instead of the default
+  # /var/run/docker.sock socket.
+  DOCKER_HOST: tcp://docker:2376
+
   # shared volume for docker-in-docker
   DOCKER_TLS_CERTDIR: "/certs"
+  DOCKER_CERT_PATH: "$DOCKER_TLS_CERTDIR/client"
 
   PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"