docker: add healthcheck

[MNThomson]

Context

Added a Docker HEALTHCHECK to both the production & dev Dockerfiles.

Now ok, this bash is absolutely cursed and could be removed by just running apt install curl. I didn't install curl since no other apt packages are installed in the runtime image and I'm assuming we want to keep the production image small. If that's acceptable though, adding curl is probably a better route.

Test

$ docker build -t libsql . && docker run --name libsql libsql

# another terminal
$ docker ps
CONTAINER ID   IMAGE    COMMAND                  CREATED              STATUS
6ac6656767ec   libsql   "/usr/local/bin/dock…"   About a minute ago   Up About a minute (healthy)

$ docker inspect --format='{{json .State.Health}}' libsql | jq

{
  "Status": "healthy",
  "FailingStreak": 0,
  "Log": [
    {
      "Start": "2024-07-15T19:43:48.64977628-07:00",
      "End": "2024-07-15T19:43:48.703180793-07:00",
      "ExitCode": 0,
      "Output": ""
    }
  ]
}

Modifying docker-health.sh to point to a port that clearly isn't running or to /doesnotexist will cause the healthcheck to fail (to simulate the /health endpoint not responding):

$ docker ps
CONTAINER ID   IMAGE    COMMAND                  CREATED              STATUS
9c889dd1ef0d   libsql   "/usr/local/bin/dock…"   About a minute ago   Up About a minute (unhealthy)

[haaawk]

What's the benefit of having those health checks @MNThomson ?

[haaawk]

Could you please rebase the PR and resolve conflicts @MNThomson ?

[flexchar]

I can chime in regards to benefits of health check - it enables modern reverse proxies such as Træfik to postpone routing traffic to unhealthy containers and monitoring services to listen and send notifications when container becomes unhealthy.

On Kubernetes environment, it is how K knows when to restart the container or which one to route from service.

It's actually a good thing. :)

[haaawk]

Thanks @flexchar . It seems that we could merge this once @MNThomson resolves the conflicts

[MNThomson]

Thanks @flexchar! Healthchecks help the container scheduler know when to recreate containers (and especially help in container dependency graphs).

Rebased @haaawk, should be good to go!