Separate purge/cleanup and try sleep hack

plugin.sh

@@ -58,10 +58,18 @@ run_stack_wait() {
 
 run_purge() {
   echo "--- start purge ---"
-  docker -H "$DOCKER_HOST" system prune --all --volumes --force
+  docker -H "$DOCKER_HOST" stack rm "$PLUGIN_STACK"
+  # See https://github.com/moby/moby/issues/30942#issuecomment-540699206
+  until [ -z "$(docker stack ps "$PLUGIN_STACK" -q)" ]; do sleep 1; done
   echo "--- end purge ---"
 }
 
+run_cleanup() {
+  echo "--- start cleanup ---"
+  docker -H "$DOCKER_HOST" system prune --all --volumes --force
+  echo "--- end cleanup ---"
+}
+
 run_plugin() {
   echo "--- start ssh-stack-deploy ---"
   load_deploy_key
@@ -77,6 +85,8 @@ run_plugin() {
   if [ "$PLUGIN_PURGE" == "true" ]; then
     run_purge
   fi
+
+  run_cleanup
   echo "--- end ssh-stack-deploy ---"
 }