Remove current pipeline droplet on master

I relalized that we let MR pipeline droplets running in order to be able to
investigate, and remove them after merging to master.
*But* for master deploys we don't terminate the droplet so we keep bumping
into our budget limit often.

.gitlab-ci.yml

@@ -175,9 +175,32 @@ behave-grafana:
       - test/**/*
       - openappstack/**/*
 
-# Remove droplet after merge
-terminate_droplet_after_merge:
+terminate_current_pipeline_droplet:
+  variables:
+    HOSTNAME: "ci-${CI_PIPELINE_ID}"
   stage: cleanup
+  before_script:
+    - echo "Terminate the current pipeline droplet on success but only for \
+      the master branch, since we wanted to have MR droplets running even for \
+      successful deploys to be able to investgate."
+  script:
+    - python3 -c "import greenhost_cloud; greenhost_cloud.terminate_droplets_by_name(\"^${HOSTNAME}\$\")"
+  only:
+    changes:
+      - .gitlab-ci.yml
+      - ansible/**/*
+      - helmfiles/**/*
+      - test/**/*
+      - openappstack/**/*
+    refs:
+      - master
+
+terminate_mr_droplet_after_merge:
+  stage: cleanup
+  before_script:
+    - echo "We leave MR droplets running even when the pipeline is successful \
+      to be able to investigate a MR. We need to terminate them when the MR \
+      is merged into master."
   script: |
     if [ "$(git show -s --pretty=%p HEAD | wc -w)" -gt 1 ]
     then
@@ -196,7 +219,7 @@ terminate_droplet_after_merge:
 terminate_old_droplets:
   stage: cleanup
   script:
-    # Remove droplet older than 2 days
+    - echo "Terminate stale, old droplets after 2 days."
     - python3 -c "import greenhost_cloud; greenhost_cloud.terminate_droplets_by_name(\"^ci-\", 2)"
   only:
     changes: