fix: use init option to prevent zombie ddev-router, for #5705

[stasadev]

The Issue

• ‹ddev poweroff› on more than one project sometimes leads to "Failed to stop project: Could not kill running container <traefik-router ID>"  #5705

API error (500): Could not kill running container d8079abded3b448b54fc3d22bc0abfe10ffbeb69cd7066027655bbf5598992d5, cannot remove - container d8079abded3b PID 1968501 is zombie and can not be killed. Use the --init option when creating containers to run an init inside the container that forwards signals and reaps processes

How This PR Solves The Issue

The error suggests to use init, it doesn't harm to try it for ddev-router:

Use the --init option when creating containers to run an init inside the container that forwards signals and reaps processes

Manual Testing Instructions

I cannot reproduce this error, at least it should not break the tests. See the issue.

Automated Testing Overview

Related Issue Link(s)

• https://stackoverflow.com/questions/49162358/docker-init-zombies-why-does-it-matter

Release/Deployment Notes

[github-actions]

Download the artifacts for this pull request:

• all-ddev-executables.zip
• ddev-linux-amd64.zip
• ddev-linux-arm64.zip
• ddev-macos-amd64.zip
• ddev-macos-arm64.zip
• ddev-windows-amd64-installer.zip

See Testing a PR

[jonaseberle]

That fixes it for me. Thank you Stanislav!

[stasadev]

Great! This will make things a little easier.

[rfay]

The SO article implies that this injects a tini process as parent of the traefik process. It seems like that could possibly have other implications. init is a strange name for them to give that behavior.

[stasadev]

Yeah, I don't really know what this change can bring and how safe it is.

[rfay]

I think this is fine. However, since we have only had the problem with the traefik router, why don't we just add the init option if we're running traefik? (Just move the init down a line.)

Apparently there is a path where the traefik binary doesn't handle signals correctly, and maybe that's what's happening.

With this, we see /sbin/docker-init injected as pid 1 in the container:

rfay@rfay-surface-goo:~/workspace/d10$ docker exec -it ddev-router bash
f70c5494795b:/mnt/ddev-global-cache/traefik$ ps -ef
PID   USER     TIME  COMMAND
    1 1000      0:00 /sbin/docker-init -- /entrypoint.sh --configFile=/mnt/ddev-global-cache/traefik/static_config.yaml
    7 1000      0:00 traefik traefik --configFile=/mnt/ddev-

docker-init is just `tini1 apparently packaged for docker's use, not sure why they use a different name:

f70c5494795b:/mnt/ddev-global-cache/traefik$ /sbin/docker-init -h
docker-init (tini version 0.19.0 - git.de40ad0)
Usage: docker-init [OPTIONS] PROGRAM -- [ARGS] | --version

Execute a program under the supervision of a valid init process (docker-init)

Command line options:

  --version: Show version and exit.
  -h: Show this help message and exit.
  -s: Register as a process subreaper (requires Linux >= 3.4).
  -p SIGNAL: Trigger SIGNAL when parent dies, e.g. "-p SIGKILL".
  -v: Generate more verbose output. Repeat up to 3 times.
  -w: Print a warning when processes are getting reaped.
  -g: Send signals to the child's process group.
  -e EXIT_CODE: Remap EXIT_CODE (from 0 to 255) to 0.
  -l: Show license and exit.

Environment variables:

  TINI_SUBREAPER: Register as a process subreaper (requires Linux >= 3.4).
  TINI_VERBOSITY: Set the verbosity level (default: 1).
  TINI_KILL_PROCESS_GROUP: Send signals to the child's process group.

I'm surprised not to see issues in the traefik queue about zombies.

[stasadev]

Great, thank you. I didn't know that this didn't happen with nginx-proxy, so it makes sense to only use it with Traefik.

I've restarted the tests to make sure everything is fine.