image-spec VS skopeo

A buildpack is a software, designed to transform application source code into executable (OCI) images that can run on a variety of cloud platforms. At its core, a buildpack is a directory that includes a specific file named buildpack.toml. This file contains metadata and configuration details that dictate how the buildpack should behave. Buildpacks in simple terms, is a set of standards defining how the different steps that are required to build a compliant container image can be automated. Using those standards, there are projects that have been built round enabling that using an CLI or an API. The most common way of doing that is through the Cloud Native Buildpacks' Pack project. Pack is a CLI command that can run in the same system the developers are using to actually go through creating a Dockerfile.

Eventually, once zstd support gets fully supported, and tiny gzip compression windows are not a limitation, then compressing a full layer would almost certainly have a better ratio over several smaller layers

https://github.com/opencontainers/image-spec/issues/803

Please note that label-schema has been superseded by https://github.com/opencontainers/image-spec/blob/main/annotations.md<^

GitHub Container Registry stores container images within your organization or personal account, and allows you to associate an image with a repository. It currently supports both the Docker Image Manifest V2, Schema 2 and Open Container Initiative (OCI) specifications.

We build all services as containerized workloads, i.e., OCI images - sometimes called Docker images. We deploy these to the Kubernetes product offered by the cloud vendor. Whenever we need some capability, containers are the answer. This insulates our applications from the vendor. In principle, we could switch providers as long as Kubernetes is available.

Build images with anything that makes OCI compliant images, push, and profit.

it's funny that you mention this because it is actually the thing that is next on my agenda for the image, as you can probably see already I bake in OCI image annotations in our image, which is great for including some core pieces of meta data. In addition to this though I will soon be including custom labels for Base64 encoded YAMLs for Kubernetes deployments using this image. I will look at including helm configuration as well. Then it should be just as easy as: $ docker pull registry.gitlab.com/crafty-controller/crafty-4:latest $ docker image inspect registry.gitlab.com/crafty-controller/crafty-4:latest | jq -r ".[].Config.Labels.\"org.arcadiatech.crafty.k8s.deployment\"" | base64 -d | kubectl apply -f -

They still don't do anything really of substance, they're just gateways to their vendor's world - booking systems, payment systems, etc. You learn those as you go along. Yes, as a potential employee, you need to be able to tick those boxes on your CV, but if you understand the underlying technology, it's mostly a matter of booking your own AWS or Azure server for $5-10 a month for a few weeks, and fooling around. (Docker is a bit different in the sense that they were the first to popularize today's de-facto container image standard, the "Docker container", which has since been accepted as a proper standard and renamed to "OCI image format"; but at the end of the day, at this point in time, Docker in itself is still just a company out for the money, and the multi-GB installation of their product can, for the essential functionality part, be replaced by a few hundred lines of Bash code. The cool boys today don't use Docker, they use [Podman(https://podman.io/), which is essentially a much more lightweight drop-in replacement ;-) )

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.