debug: echo length of ci-vars

.gitlab-ci.yml

@@ -29,6 +29,8 @@ docker-push:
     - docker:dind
   before_script:
     # default repo is docker.io (aka docker hub)
+    - echo ${#DOCKER_ID}
+    - echo ${#DOCKER_HUB_AUTH}
     - docker login -u "$DOCKER_ID" -p "$DOCKER_HUB_AUTH"
   script:
     # every commit on main branch should build image as unstable