Employ use of drone version/tag instead of separate images, lb as global schedule.

templates/drone/4/docker-compose.yml.tpl

@@ -1,7 +1,7 @@
 version: '2'
 services:
   agent:
-    image: ${drone_agent_image}
+    image: drone/agent:${drone_version}
     environment:
       DRONE_SERVER: ${drone_server}
       DRONE_SECRET: ${drone_secret}
@@ -27,7 +27,7 @@ services:
       io.rancher.scheduler.affinity:container_label_soft_ne: io.rancher.stack_service.name=$${stack_name}/$${service_name}
       io.rancher.container.hostname_override: container_name
   server:
-    image: ${drone_server_image}
+    image: drone/drone:${drone_version}
     environment:
       DRONE_HOST: ${drone_host}
       GIN_MODE: ${gin_mode}
@@ -111,7 +111,6 @@ services:
     image: rancher/lb-service-haproxy:v0.6.4
     ports:
       - ${host_port}:${host_port}
-    links:
-      - server:server
     labels:
+      io.rancher.scheduler.global: 'true'
       io.rancher.scheduler.affinity:host_label_soft: drone_lb=true