amazon-eks-ami VS skopeo

Careful assuming system reserved will be present. Last I checked, AWS EKS does not have system reserved resources for the kubelet by default and as a result, pods can starve those for resources (e.g., https://github.com/awslabs/amazon-eks-ami/issues/79). This is of course more important for memory, but could impact CPU as well.

For example, this is available for AL2: https://github.com/awslabs/amazon-eks-ami

I found this document that lists the pod limits per node size. I suspect you will want to consider larger worker nodes or you will very quickly be unable to schedule additional workloads.

source

Issue 1 is a known issue due to memory reservation being to low, see e.g. https://github.com/awslabs/amazon-eks-ami/issues/1145

No, the new node is added if there are not enough resiurces to start a new pod. So if you have many pods with small resource usage you can hit the pod per node limit, on eks you have a max number of pods depending on the instance type - https://github.com/awslabs/amazon-eks-ami/blob/master/files/eni-max-pods.txt You can incerase that limit : https://docs.aws.amazon.com/eks/latest/userguide/cni-increase-ip-addresses.html

# of pods are essentially capped by the worker node choice.

below excerpt from: https://github.com/awslabs/amazon-eks-ami/blob/master/files/...

  # Mapping is calculated from AWS EC2 API using the following formula:

See also: EKS nodes lose readiness when containers exhaust memory

So it manifests itself in this way: your pod is scheduled but remains pending forever. You check the logs and you see that it's complaining that the an IP address. Ultimately, if you check here, you see the maximum number of pods that can be scheduled on any underlying ec2 instance, even if you have remaining IPs in your subnet. I found this to be one of the most poorly understood phenomena in EKS. Even those who claimed to "crack" it and wrote fancy blog posts about it fundamentally got it wrong. AFAIK this document reflects the official AWS guide on how to mitigate this.

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.