dumb-init VS Lean and Mean Docker containers

I think you are on the right track in thinking it’s a signal handling issue. You mentioned using some “bash scripts”, have you tried something like dumb-init?

At the other extreme, there's dumb-init - it implements the special pid-1 behaviors and acts as a wrapper around the one script you want to run. It's ideal for containers or virtual machines that don't need user logins or more than one service.

Oh, and another thing. Many containers launch their main process from a shell script. When this happens, the shell script receives the SIGTERM event, not the application. Your shell script MUST relay SIGTERM events back to the main process, and it doesn’t happen by default. You can use a shell script wrapper, like dumb-init (https://github.com/yelp/dumb-init), as your entry point if you need to use a shell script on container startup.

It's a plus because Gentoo fully supports the choice of Systemd or OpenRC. It also has minit, dumb-init, sysvinit, cinit in tree for the more adventurous. No one was calling the AUR bloat, the parent comment just mentions that Gentoo has an equivalent project, GURU.

, but I prefer to not have to make this assumption and use an init system instead.

[1]: https://github.com/Yelp/dumb-init

> It has no init system.

Apologies that I can't link directly to the "--init" flag but docker actually does have an init, it's just (err, was?) compiled into the binary: https://docs.docker.com/engine/reference/commandline/run/#op...

My recollection is that it either adopted, or inspired, https://github.com/Yelp/dumb-init#readme which folks used to put into their Dockerfile as the init system back in the day

Folks (ahem, I'm looking at you, eks-anywhere[0]) who bundle systemd into a docker container are gravely misguided, and the ones which do so for the ability to launch sshd alongside the actual container's main process are truly, truly lost

0: https://github.com/aws/eks-anywhere/issues/838#issuecomment-...

You can use something like dumb-init which is designed to correctly handle signals

And if you want to make the container quickly secure without bloats, maybe give this a try https://github.com/slimtoolkit/slim

Slim.ai presents the data in a more user friendly way than many of the other tools in this post. On top of its open source SlimToolkit for identifying the contents of an image, Slim.ai uses Trivy for vulnerability scanning.

What about https://github.com/slimtoolkit/slim?

A last practice that I do not use at all and which may interest you is to use slim toolkit to keep only the useful elements in your final image.

Anyone tried using https://github.com/docker-slim/docker-slim To minify an image?..

Distroless images are better left for people with serious need for lightweight images and good Linux knowledge because they require lot of planning with the build so that they stay light and work. If you need lighter images but docker isn't your main tool and you can't afford to take hours and hours of practicing different build strategies you can check docker-slim (https://dockersl.im/). With this tool you can easily size down the images.

Maybe this would help in that regard: https://github.com/docker-slim/docker-slim