skopeo VS buildkit

I decided to go searching for an alternative means to pull a docker image. In my search I discovered Skopeo, an alternative method to download Docker images that proved to be surprisingly effective. It not only downloaded the image faster, it also allowed me to save my image in a tar file, which means you can pull an image on one system and share that image to another system, loading it easily to docker instance on that system. This can be very beneficial if you have multiple systems and don't want to download an image multiple times.

But I'd suggest looking into if it's solved by other tools already, like regclient/regclient and their regsync features or something like containers/skopeo.

Have a use case where we have a CLI (built with cobra) for our dev teams which can execute common tasks. One of those tasks we want to implement is to copy docker images from the internet to our internal registry. A tool such as skopeo can do this and much more. Instead of essentially re-writing the functionality directly into our CLI we'd like to embed it. This would also negate the need for the dev teams to manage multiple CLI tools.

Self hoisting here, I put this together to make it easier to generate single (extra) layer docker images without needing a docker agent, capabilities, chroot, etc: https://github.com/andrewbaxter/dinker

Caveat: it doesn't work on Fly.io. They seem to be having some issue with OCI manifests: https://github.com/containers/skopeo/issues/1881 . They're also having issues with new docker versions pushing from CI: https://community.fly.io/t/deploying-to-fly-via-github-actio... ... the timing of this post seems weird.

FWIW the article says

> create a Docker image, also known as an OCI image

I don't think this is quite right. From my investigation, Docker and OCI images are basically content addressed trees, starting with a root manifest that points to other files and their hashes (root -> images -> layers -> layer configs + files). The OCI manifests and configs are separate to Docker manifests and configs and basically Docker will support both side by side.

skopeo is another tool worth looking into. we've started deploying amd and arm nodes into our k8s clusters, and this tool was incredibly easy to build around for getting multi-arch images into our container registry.

I would use skopeo, the tool is quite handy for working with remote images. https://github.com/containers/skopeo

Using distroless images not only reduces the size of the container image it also reduces the surface attack. The need for container image signing is because even with the distroless images there is a chance of facing some security threats such as receiving a malicious image. We can use cosign or skopeo for container signing and verifying. You can read more about securing containers with Cosign and Distroless Images in this blog.

Look at using tools like skopeo or crane

You could try some commandline tool like skopeo to fetch the image tags regularly and do some shell magic to notify you on any change you want

This is what Podman, an open-source daemonless and rootless container engine, was developed with in mind. Podman runs using the runC container runtime process, directly on the Linux kernel, and launches containers and pods as child processes. In addition, it was developed for the Docker developer, with most commands and syntax seamlessly mirroring Docker's. Buildah, an image builder, and Skopeo, the image utility tool, are both complimentary to Podman as well, and extend the range of operations able to be performed.

> 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.