skopeo VS regclient

I believe skopeo should allow you to: https://github.com/containers/skopeo

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

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.

This is possible with the help of regctl.

I've been working on some stuff last couple of days to give me this function. Together with regctl I've got some drafts working.

with more options like auth and certs. Infra might include backing disk and LB; if you need to scale, run several and keep them in sync with one of many open tools eg regclient.

Also plenty of cloud services now have registries like GHCR, ECR, etc. which are basically pay per Gb.

https://docs.docker.com/registry

https://github.com/regclient/regclient

I had a similar problem and ended up using regctl. You might have to tweak your docker config depending on the registries you use, by setting a file type ci/cd envvar with the name DOCKER_CONFIG