Docker-Compose Restart Policy

Question

I looked thru the docs for docker-compose and I see that Version 3 has a deploy restart policy but it's only for swarm. I tried setting restart_policy on my service but got this error:

ERROR: The Compose file './docker-compose.yml' is invalid because:
Unsupported config option for services.web: 'restart_policy'

Is there any way to set a restart policy on services created using docker-compose outside of a swarm?

Answer 1

It looks like a gap in the documentation

In 3rd version, we can still use "restart" inside services same as before in v.2 (except for deploy into swarm)

version: '3'
services:
  my-service:
    restart: on-failure:5 

https://docs.docker.com/compose/compose-file/#restart

Answer 2

Even if you're NOT in swarm mode, there is an option called --compatibility which will work with restart_policy, this will attempt to restart even if your not deploying. The only glitch, is the sub-keys of 'delay' and 'window' will be ignored. Here is an example:

version: '3.7'
services:
  build:
    context: .
    dockerfile: Dockerfile
  container_name: example
  deploy:
    restart_policy:
      condition: on-failure
      max-attempts: 3

run this command:

docker-compose -f docker-compose.yml --compatability up

Answer 3

Version 2 supports restart policies, using the restart keyword, and should work fine for you if you don't need Swarm (which you said you don't need/want).

version: '2'
services:
  web:
    image: apache
    restart: always

https://docs.docker.com/compose/compose-file/compose-file-v2/#restart

Compose format version 3 has a parameter called restart_policy, but so far as I can tell from documentation it is only valid as part of deploy, which is only used when deploying to a Swarm. So version 3 is probably not useful in your case.