rules_docker VS nerdctl

My company uses Bazel's rules docker to build our images: https://github.com/bazelbuild/rules_docker

They're pretty great and have a lot of the caching and parallelism benefits mentioned in the post for free out of the box, along with determinism (which Docker files don't have because you can run arbitrary shell commands). Our backend stack is also built with Bazel so we get a nice tight integration to build our images that is pretty straightforward.

We've also built some nice tooling around this to automatically put our maven dependencies into different layers using Bazel query and buildozer. Since maven deps don't change often we get a lot of nice caching advantages.

I've seen rules_docker is looking for maintainers here ; Does this mean it doesn't use it that much internally? If so, how do they go about using other services e.g docker-compose for running external services e.g database?

Did you mean this one? https://github.com/bazelbuild/rules_docker

I was very interested in this Bazel-based way of building containers but its README page says "it is on minimal life support," which does not inspire confidence. How's your experience using it?

As others have said docker in docker or a separate build server are your best options using docker. You can also use Bazel (which doesn't require the docker daemon) to build docker images which will build deterministic images every time due to not incorporating the timestamp: https://github.com/bazelbuild/rules_docker

There's some BazelCon talks about people doing similar stuff but not actually open sourcing their code.

P.S. if you use rules_docker please feel free to open a PR to add your company to our README: https://github.com/bazelbuild/rules_docker/#adopters

The docker utility isn't the only way to build and run containers. There's also cri-o, podman, and crun among others for running containers. For building there is podman again, Jib for Java applications, and bazel plus many others. The docker approach of using a client to connect to a daemon required to run as root has turned out to be slow and insecure.

During the last 3 years I've had the pleasure of using Bazel's rules_docker to generate all my container images (https://github.com/bazelbuild/rules_docker).

In a nutshell, rules_docker is a set of build rules for the Bazel build system (https://bazel.build). What's pretty nice about these rules is that they don't rely on a Docker daemon. They are rules that directly construct image tarballs that you can either load into your local Docker daemon or push to a registry.

What's nice about this approach is that image generation works on any operating system. For example, even on a Mac or Windows system that doesn't have Docker installed, you're able to build Linux containers. They are also fully reproducible, meaning that you often don't need to upload layers when pushing (either because they haven't changed, or because some colleague/CI job already pushed those layers).

I guess rules_docker works fine for a variety of programming languages. I've mainly used it with Go, though.

Direct use of containerd? containerd? turns out I didn't know anything about container technology. containerd was originally developed by Docker in 2015 as a daemon that provided basic container management capabilities under Docker. containerd's scope has gradually expanded and now seems to cover almost everything in the Docker Engine. For example, nerdctl is a CLI for containerd; the UX is almost identical to the Docker CLI, and Docker Compose is also supported (nerdctl compose).

Nerdctl[1] (for containerd) works fine with docker-compose.yml for my purposes (which are not much). The only issue I encountered was with environment variable substitution not working the same as docker-compose, but I didn't look hard for a solution and edited my compose file

1. https://github.com/containerd/nerdctl mine came bundled with Rancher desktop, and 'nerdctl compose up' is all I've needed

I haven't tried it personally but you might be able to export the tar from docker host with docker cli and then load it on containerd host using nerdctl - https://github.com/containerd/nerdctl

It looks like the real nice thing here is having a formula for QEMU with the ARM patch applied: https://github.com/simnalamburt/qemu/tree/hvf

With this I believe you could also used [nerd](https://github.com/containerd/nerdctl) instead of podman but I haven't tested it yet.

One area, where containerd didn't had a first class support was CLI. the default containerd CLI "ctr" has a very naive implementation. The reason for that I believe is, containerd as a system was never meant to be consumed by humans, and was designed to be consumed by higher layers e.g. orchestration systems like nomad or k8s. However, with the deprecation of dockershim in k8s, and users moving to containerd, a new docker compatible CLI came out:

https://github.com/AkihiroSuda/nerdctl

If you just have containerd running on your system (with no docker daemon running), you can just install nerdctl and add

alias docker="nerdctl"

to your ~/.bashrc file.

Then you can just run any docker commands the way you used to with docker, and it will run those commands against the containerd API giving you the same CLI experience that you used to have with docker.