s6-overlay VS litestream-s6-example

FROM docker.io/grafana/grafana-oss:9.5.12-ubuntu # Set USER to root escalating priviliges to perform installation of litestream and s6-overlay USER root RUN apt-get -qq update && \ apt-get -qq install -y xz-utils \ && rm -rf /var/libs/apt/lists/* # https://github.com/benbjohnson/litestream-s6-example/blob/main/Dockerfile # Download the static build of Litestream directly into the path & make it executable. ADD https://github.com/benbjohnson/litestream/releases/download/v0.3.11/litestream-v0.3.11-linux-amd64.tar.gz /tmp/litestream.tar.gz RUN tar -C / -xvzf /tmp/litestream.tar.gz ARG S6_OVERLAY_VERSION="3.1.5.0" # Download the s6-overlay for process supervision. ADD https://github.com/just-containers/s6-overlay/releases/download/v${S6_OVERLAY_VERSION}/s6-overlay-noarch.tar.xz /tmp RUN tar -C / -Jxpf /tmp/s6-overlay-noarch.tar.xz ADD https://github.com/just-containers/s6-overlay/releases/download/v${S6_OVERLAY_VERSION}/s6-overlay-x86_64.tar.xz /tmp RUN tar -C / -Jxpf /tmp/s6-overlay-x86_64.tar.xz # Copy s6 init & service definitions. COPY etc/s6-overlay /etc/s6-overlay # Copy Litestream configuration file. COPY etc/litestream.yml /etc/litestream.yml # The kill grace time is set to zero because our app handles shutdown through SIGTERM. ENV S6_KILL_GRACETIME=0 # Sync disks is enabled so that data is properly flushed. ENV S6_SYNC_DISKS=1 # Reset USER to 472 to reset the escalated privileges USER 472 # # Run the s6 init process on entry. ENTRYPOINT [ "/init" ]

Learn S6-Overlay that allows to have one docker container for multiple processes... make immich docker compose not a two page 8 containers long? But just one clean container with healthcheck. Convince the devs to switch to it.

Custom base docker image with S6 overlay (for more details : just-containers/s6-overlay)

https://github.com/just-containers/s6-overlay can do what you need.

Used s6-overlay[1] to start a lot daemons in a docker-image for demo purposes - postgres, tomcat, mysql, php-fpm, apache (don't ask why ;) - s6 worked really well and was reliable and stable - I enjoyed it very much. It was also possible to reliable pass SIGTERM to the daemons in the image for clean shutdown and it was easily possible to configure logging to stdout with a prefix. Modelling dependencies (waiting on database before starting app etc.pp) is possible via shell-scripts. It's super flexible but out of the box it's more like a collection of powerful tools not a complete package - but that's good. It's in the tradition of djb daemontools and is very unix - as in doesn't talk a lot and you better know how each part works but - and that's really cool - it's modular and simple and once you get a grip on it you can easily reason about it. systemd takes a completely different approach and also solves a kind of differnt problem - this is like small pieces of lego that compose well instead of one big chunk of glib/dbus/glibc only c-code.

1: https://github.com/just-containers/s6-overlay

Every container has some entrypoint, whether it launches a single binary, runs a "process supervisor" like s6, or does some pre-setup before running a service, like a database.

If you *really* want to make your own containers with PUID/PGID support checkout "S6-overlay" and the linuxserver "baseimage". Somewhere in the startup they end up running:

FROM ubuntu:20.04 ARG S6_OVERLAY_VERSION=3.1.0.1 ARG DEBIAN_FRONTEND=noninteractive ENV TZ="America/New_York" RUN apt-get update && apt-get install -y xz-utils ADD https://github.com/just-containers/s6-overlay/releases/download/v${S6_OVERLAY_VERSION}/s6-overlay-noarch.tar.xz /tmp RUN tar -C / -Jxpf /tmp/s6-overlay-noarch.tar.xz ADD https://github.com/just-containers/s6-overlay/releases/download/v${S6_OVERLAY_VERSION}/s6-overlay-x86_64.tar.xz /tmp RUN tar -C / -Jxpf /tmp/s6-overlay-x86_64.tar.xz RUN apt-get autoclean && rm -rf /tmp/* ENTRYPOINT ["/init"]

Not sure about unbound or what have inside the pihole base image, you may try to run the service in foreground or use some tiny init service for that container (I just learnt that s6 may work for that, but you must be aware how it should be used)

Now on to how to use litestream with s6-overlay. benbjohnson creator of litestream has a repo over how to use litestream and s6-overlay with a go app container but the repo is publicly archived. Its probably so becuase its uses s6-0verlay version 2 while the newer version is 3 and its got a new design over how to organise your application and define the run scripts and dependencies.

The minor hack is in that trailing &. It tells the script to run the Litestream process in the background, which is how I can execute two long-running processes in the same Docker container. Ben Johnson has published a cleaner solution, but I'm using the hacky version for ease of demonstration.