dumb-init VS dive

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

Cool, gonna try this soon. Would be great to use in combination with Dive (https://github.com/wagoodman/dive)

Dive is an open-source tool that allows you to explore the various layers of a Docker image. It shows you the content of each layer and helps you identify voluminous or unnecessary parts.

Dive is a great tool for debugging this. I like image reduction work just because it gives me a chance to play with Dive: https://github.com/wagoodman/dive

One easy low hanging fruit I see a LOT for ballooning image sizes is people including the kitchen sink SDK/CLI for their cloud provider (like AWS or GCP), when they really only need 1/100 of that. The full versions of both of these tools are several hundred mb each

This post is going to be shorter. I'd like to highlight a tool that I really enjoy working with called "Dive" It is an essential tool when working to build and optimize docker containers.

Whether you work with Docker regularly or even create your own Docker containers, Dive is a great tool for streamlining image sizes, potentially helping you save storage costs and speed up deployments.