nerdctl VS buildkit

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.

> We are uding docker-in-docker at the moment

You can also run a "less privileged" container with all the features of Docker by using rootless buildkit in Kubernetes. Here are some examples:

https://github.com/moby/buildkit/tree/master/examples/kubern...

https://github.com/moby/buildkit/blob/master/examples/kubern...

It's also possible to run dedicated buildkitd workers and connect to them remotely.

- BuildOp evaluates its input as additional LLB operations to add to the graph to allow for dynamic build graphs (also unused in the Dockerfile frontend)

With the Dockerfile Explorer, we run the Dockerfile frontend[1] that BuildKit uses inside of WASM to parse and produce the LLB output locally in your browser. We then embed the Monaco Editor so that you can change your Dockerfile to see how it impacts the LLB output that BuildKit will use to build your Docker image.

You can see a quick video and read more details on how it all works here: https://depot.dev/blog/dockerfile-explorer.

We'd love any feedback or ideas folks would like around this type of tool!

[0] https://github.com/moby/buildkit#exploring-llb

Now since Kubernetes works off of containerd I'll be taking a different approach on handling container builds by using nerdctl and the buildkit that comes bundled with it. I'll do this on the amd64 control plane node since it's beefier than my Raspberry Pi workers for handling builds and build related services. Go ahead and download and unpack the latest nerdctl release as of writing (make sure to check the release page in case there's a new one):

There's a 2-year-old moby/buildkit GitHub issue about frequent build cache misses when using the BuildKit docker-container driver and multi-stage builds. Anyone else in this sub run into this problem and/or have reasonable workarounds? It seems like something that should come up pretty often.

A couple months ago I encountered a bug in buildkit - when enabling OpenTelemetry tracing, we got occasional panics. With a bit of investigation, we found the cause, fixed and tested in our fork and internal deployments, and pushed to upstream.

I do some search in the internet and there seems to be no good solution, so I just create a feature request: https://github.com/moby/buildkit/issues/3859

Yeah, only Linux containers at the moment, BuildKit is the way we are constructing pipelines and doing caching. Split on if we will support non-linux hosts, but definitely want to find a good solution to not doing Docker-in-Docker.

Relevant issues are https://github.com/moby/buildkit/issues/3011 and https://github.com/moby/buildkit/issues/1512.