Alpine with S6-Overlay

I want a docker image that behaves more like a VM:

1. I can start / stop many processes, also the main process (usually PID 1) Why? To test things out. Changing environment variables, debugging with the coredump file or recompiling the app without crashing the container follows much more my development process
2. Logging to a seperate file with logrotation Why? Docker logs (and Kibana) are a pain in the ass!
3. Watchdog: k8s restarts containers when they are crashing. That should be done by the s6-overlay.

Tested

• Starting & Stopping services with s6-rc start myapp and s6-rc stop myapp
• Watchdog: Restart works, tested with kill
• docker exec into the container and run myapp manually, it uses the env vars of the shell
• Logging: /var/log/myapp/current is filled
• Logrotation: With ps aufxww, you can see that s6-log -b -- n20 s1000000 T /var/log/myapp is running, which means that it rotates when the file becomes 1MB, it keeps 20 files and with T prepends ISO 8601 timestamp to each line
• Cron
• Coredump