Set 'latest' tag on every push to Docker Hub

Set a tag latest on every push to Docker Hub. This way, latest always points to the most recent version of the Git master branch. Not that the tag latest used to point to the latest release! So this changes behavior!

A new tag stable has been introduced, which is a substitute for the old latest tag. It can be set by manually running the job deploy_docker_tag_stable, and should point to the latest release.

Closes RAP-524

.gitlab-ci.yml

@@ -200,7 +200,9 @@ deploy_docker:
     - echo $DH_REGISTRY_PASSWORD | docker login -u $DH_REGISTRY_USER --password-stdin
   script:
     - docker tag $INTEGRATION_IMAGE astronrd/linc:$LINC_VERSION
+    - docker tag $INTEGRATION_IMAGE astronrd/linc:latest
     - docker push astronrd/linc:$LINC_VERSION
+    - docker push astronrd/linc:latest
   rules:
     # Only run on master
     - if: '$CI_COMMIT_BRANCH == "master"'
@@ -237,7 +239,7 @@ deploy_release:
     - if: '$CI_COMMIT_BRANCH =~ /^releases//'
       when: always
 
-deploy_docker_tag_latest:
+deploy_docker_tag_stable:
   stage: deploy
   needs: ["versioning", "download_data"]
   when: manual
@@ -248,5 +250,5 @@ deploy_docker_tag_latest:
     - echo $CI_REGISTRY_PASSWORD | docker login -u $CI_REGISTRY_USER --password-stdin $CI_REGISTRY
     - echo $DH_REGISTRY_PASSWORD | docker login -u $DH_REGISTRY_USER --password-stdin
   script:
-    - docker tag $INTEGRATION_IMAGE astronrd/linc:latest
-    - docker push astronrd/linc:latest
+    - docker tag $INTEGRATION_IMAGE astronrd/linc:stable
+    - docker push astronrd/linc:stable