Implementing Consul healthcheck in Docker environment

Question

I am new with Consul/Registrator and Docker. I am confused about using the Consul healthcheck in Docker environment. It is described in the following link, within the section Docker + Interval: https://www.consul.io/docs/agent/checks.html

Here is the example of Consul healthcheck definition described in the link:

{
  "check": {
    "id": "mem-util",
    "name": "Memory utilization",
    "docker_container_id": "f972c95ebf0e",
    "shell": "/bin/bash",
    "args": ["/usr/local/bin/check_mem.py"],
    "interval": "10s"
  }
}

Is the healthcheck script within the docker image or outside of it (in the example: check_mem.py)? Should we know the ID of the container and manually insert in the field: docker_container_id? (this would be not very efficient way)

I have been googling around and the only answer that I can find is at the end of the following discussion: https://github.com/hashicorp/consul/issues/3182

But this code is some 'workaround' - it uses the docker 'primal' healthcheck and the registrator variable - ENV SERVICE_CHECK_SCRIPT. It does not use consul healthcheck script.

Can anybody help me with understanding how consul healthcheck works in docker environment.

Answer 1

The docker healthcheck runs within the docker container.

Your example is equivalent to docker exec f972c95ebf0e /bin/bash /usr/local/bin/check_mem.py