s6-overlay VS bocker

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)

A (joke?) one-liner I came up with while thinking about solutions to centralized container management across multiple SSH hosts. Shame on me.

The name is inspired by bocker [0], albeit this doesn't re-implement docker-compose in bash, I found it to be fitting enough.

I'd love to see someone come up with a smarter and/or shorter way to do this.

[0] https://github.com/p8952/bocker

When I did a talk about docker I also wanted to show a bit of what it does under the hood without going through all the layers and without too much details. This ~120 lines of shell script is really good in providing just an intro into what's needed for containers: https://github.com/p8952/bocker/blob/master/bocker

i tried it and like the concnpt, but until it can be launched via a systemd userspace service (without previously manually booting it) among other problems i will keep using docker (or bocker)

> But you couldn't reimplement podman in a few hundred lines of code.

You don't even need a few hundred: https://github.com/p8952/bocker

And then there's 'dokku' which IIRC, started as a bash version of Heroku.

> Not all ideas have the same quality.

They really do. I've heard all kinds of things in my career, but almost none I would want to dedicate a portion of my life building. Not because they are bad ideas or won't work, but because of the person with the idea or it just didn't interest me. Those people went on to be moderately successful (like hundreds of millions worth) but I'm glad I wasn't on that ride.

Bocker is in this same category...docker clone in bash that's helpful in seeing what's really happening underneath with nsenter, namespaces, network bridging, cgroups, etc.

https://github.com/p8952/bocker

Docker implemented in around 100 lines of bash: https://github.com/p8952/bocker

This is the most mindblowing example for enterprise security teams that think Docker is a new threat on a single tenant Linux host.

No, buddies, all this stuff is already there. If you were fine with your visibility before*, you're still fine. Go find a real problem while we play with our developer dopamine.

* NARRATOR: They shouldn't have been.

Bocker[1] does a reasonably good job of showing the value of Docker was mostly in Docker hub.

[1] https://github.com/p8952/bocker

There is a cool project I've seen called "bocker" (https://github.com/p8952/bocker) which is something of a proof of concept of implementing Docker with bash, which speaks a bit to how Docker is indeed in many ways an amalgam of lower level primitives (such as chroot as you mentioned). Pretty neat!