fasmide/god

Lightweight supervisord replacement

god

Lightweight supervisord-like thing for use as pid-eins in containers

CAUTION: this code have not seen much battletesting

Goals

• Simple limited featureset
• If any of god's processes exits, try to shutdown other processes or timeout
• Reap zombies (Use --init for this, available for docker-run, docker-service-create and the docker-compose format)
• Basic dependency-based start of processes

Known issues

• If shutdown signal is received while god waits for dependencies to fulfill - these processes may start even when supposed not to.

Signal logic

If SIGTERM, SIGQUIT or SIGINT is received, god will try to shutdown by sending SIGQUIT (can be overwritten with stop_signal) to all processes.

config.yml

shutdown_timeout: 9s # defaults to 1 minute
processes:
  - name: nginx
    cmd: nginx -g 'daemon off;' -c $NGINXCONF
    # Setting bash: true allows one to use environment variables
    # and other bash hackery by passing `cmd` to `bash -c` for convenience
    bash: true

  - name: cloudflared
    cmd: cloudflared tunnel --no-autoupdate --unix-socket /var/run/website.sock
    stop_signal: SIGQUIT # if for whatever reason the default SIGTERM wont do 
    # this process will not start until a `/var/run/website.sock` 
    requires:
      - exists: /var/run/website.sock
        timeout: 10s

  - name: php
    cmd: php-fpm

  # this "process" exits for demo purposes making the daemon send stop signals
  # to other processes and eventually exit
  - name: stop-everything-after-a-minute
    cmd: sleep 60

Docker example

Build

docker build -t cego/god .

Then use the image in a another docker multistage build

.... 

COPY --from=cego/god /god /god
COPY config.yml /config.yml

....

CMD ["/god"]