ENH: use cached docker image building

.gitlab-ci.yml

@@ -20,12 +20,6 @@
 
 variables:
    CI_REGISTRY_IMAGE: $CI_REGISTRY/caosdb-pyint-testenv
-   # When using dind, it's wise to use the overlayfs driver for
-   # improved performance.
-   DOCKER_DRIVER: overlay2
-
-services:
-  - docker:19.03.0-dind
 
 stages:
   - setup
@@ -79,6 +73,9 @@ stages:
 # These volumes are inteded to be used for testing server-side scripting and
 # file-system features.
 #
+services:
+  - docker:19.03.0-dind
+
 test:
   tags: [docker]
   stage: test
@@ -88,11 +85,11 @@ test:
             CAOSDB_TAG=dev-latest;
         fi
       - echo $CAOSDB_TAG
-      - KNOWN_TAGS=$(curl -u testuser:$CI_REGISTRY_PASSWORD -X GET https://$CI_REGISTRY/v2/caosdb/tags/list)
+      - KNOWN_TAGS=$(curl -u indiscale:$CI_REGISTRY_PASSWORD -X GET https://$CI_REGISTRY/v2/caosdb/tags/list)
       - echo $KNOWN_TAGS
         # test if the caosdb registry knows our current tag
       - echo $KNOWN_TAGS | grep "$CAOSDB_TAG"
-      - docker login -u testuser -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+      - docker login -u indiscale -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
       - docker pull $CI_REGISTRY_IMAGE:latest
       - cd .docker
         # here the server and the mysql backend docker are being started
@@ -115,14 +112,14 @@ test:
     expire_in: 1 week
 
 build-testenv:
-  tags: [notls]
-  image: docker:18.09
+  tags: [cached-dind]
+  image: docker:19.03
   stage: setup
   only:
-      - schedules
+    - schedules
   script:
       - df -h
-      - docker login -u testuser -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+      - docker login -u indiscale -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
         # use here general latest or specific branch latest...
       - docker build 
         --file .docker/Dockerfile
@@ -141,7 +138,7 @@ cert:
       - cd .docker
       - CAOSHOSTNAME=caosdb-server ./cert.sh
 style:
-  tags: [notls]
+  tags: [docker]
   stage: style
   image: $CI_REGISTRY_IMAGE:latest
   script: