set docker host and certdir

.gitlab-ci.yml

@@ -8,6 +8,8 @@ stages:
 
 variables:
   IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME
+  DOCKER_HOST: tcp://docker:2375
+  DOCKER_TLS_CERTDIR: ""
 
 cache:
   key: ${CI_PROJECT_ID}