Restarting an unhealthy docker container based on healthcheck

Question

I am using Docker version 17.09.0-ce I see that containers are marked as unhealthy incase of health check failures.

Is there an option to get the container restart instead of keeping the container as unhealthy.

Answer 1

Restarting of unhealty container feature was in the original PR (https://github.com/moby/moby/pull/22719), but was removed after a discussion and considered to be done later as enhancement of RestartPolicy.

At this moment you can use this workaround to automatically restarting unhealty containers: https://hub.docker.com/r/willfarrell/autoheal/

Here is a sample compose file:

version: '2'
services:
  autoheal:
    restart: always
    image: willfarrell/autoheal
    environment:
      - AUTOHEAL_CONTAINER_LABEL=all
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock

Simply execute docker-compose up -d on this

Answer 2

For standalone containers, Docker does not have native integration to restart the container on health check failure though we can achieve the same using Docker events and a script. Health check is better integrated with Swarm. With health check integrated to Swarm, when a container in a service is unhealthy, Swarm automatically shuts down the unhealthy container and starts a new container to maintain the container count as specified in the replica count of a service.

Answer 3

Docker has a couple of ways to get details on container health. You can configure health checks and how often they run. Also, health checks can be run on applications running inside a container, like http (this would use curl --fail option.) You can view the health_status event to get details.

For detailed information on an unhealthy container the inspect command comes in handy, docker inspect --format='{{json .State.Health}}' container-name (see https://blog.newrelic.com/2016/08/24/docker-health-check-instruction/ for more details.)

You should resolve the error condition causing the "unhealthy" tag (anytime the health check command runs and gets an exit code of 1) first. This may or may not require that Docker restart the container, depending on the error. If you are starting/restarting your containers automatically, then either trapping the start errors or logging them and the health check status can help address errors quickly. Check the link if you are interested in auto start.

Answer 4

According to https://codeblog.dotsandbrackets.com/docker-health-check/

Create container and add " restart: always".

In the use of healthcheck, pay attention to the following points:

For standalone containers, Docker does not have native integration to restart the container on health check failure though we can achieve the same using Docker events and a script. Health check is better integrated with Swarm. With health check integrated to Swarm, when a container in a service is unhealthy, Swarm automatically shuts down the unhealthy container and starts a new container to maintain the container count as specified in the replica count of a service.