include a healthcheck binary for use in a docker compose environment

[rgl]

in order to have a healthcheck in docker compose we need a command that returns a 0 exit code.

we either need a mailpit sub-command or an http client (e.g. curl) binary available inside the container.

for example, this docker compose file, uses curl (but a better approach would be to implement something equivalent of this example, but as a mailpit sub-command, e.g., mailpit readyz):

# see https://github.com/compose-spec/compose-spec/blob/master/spec.md
# see https://github.com/opencontainers/image-spec/blob/master/annotations.md
services:
  mailpit:
    # see https://hub.docker.com/r/axllent/mailpit
    # see https://github.com/axllent/mailpit
    # see https://mailpit.axllent.org/docs/install/docker/
    image: axllent/mailpit:v1.13.3
    command:
      - --smtp-auth-accept-any
      - --smtp-auth-allow-insecure
    ports:
      # smtp.
      # http://localhost:1025
      - 1025:1025
      # http.
      # http://localhost:8025
      - 8025:8025
    healthcheck:
      test: ["CMD", "curl", "--silent", "--fail-with-body", "--max-time", "5", "http://localhost:8025/readyz"]
      interval: 15s
      timeout: 5s
      retries: 2
    restart: on-failure

with this in place, we can use docker compose up --wait, to make it wait for all the containers/services within the docker compose environment to being healthy.

[axllent]

Thanks for the input @rgl, I'll look into this. The easiest solution would be to add curl to the Docker image - but I do see the benefits of a subcommand with a limited set of arguments, more specifically the listening interface & port (both as a commandline option and existing ENV variables). This way the docker image would only need to run mailpit ready (or similar) and return the exit status.

[axllent]

This has been released in v1.15.1. I added a readyz subcommand which, in Docker, should auto-detect the port, webroot and HTTPS status of the running daemon. I also added this to the Dockerfile so you probably do not need to specify your own (unless you wish to use different defaults) 👍

Please confirm it works as you expect?

[rgl]

It works as expected! Thank you!