This repository contains simple scripts and associated Docker image to aid in obtaining and bundling up the Kubernetes system images into a TAR archive which can then be used with docker load to bootstrap the image registry on offline/air-gapped systems.
Run the bundle-k8s-images.sh script passing in the desired Kubernetes version and optionally the kubeadm image version to use e.g.
> ./bundle-k8s-images.sh -k 1.10.11 -a v1.11
Will produce a k8s_v1.10.11_images.tar file.
Where options can be viewed by running with the -h option. Only required option is -k <k8s-version> to specify the desired Kubernetes version.
NB: This feature of kubeadm was only added from 1.11 onwards and kubeadm is typically only able to provide images for versions within 1 minor version of it. Therefore you should use an image version as close to the desired Kubernetes version as possible. The -a <kubeadm-version> option specifies the desired kubeadm image version, if omitted the script selects a version based on the specified -k <k8s-version> option which may not be correct when targeting older versions of Kubernetes.
WARNING: The set of images returned by kubeadm can be sensitive to the --feature-gates used on your cluster. You should use the -f <feature-gates> option to the script to specify any relevant feature gates or the set of bundled images may not be sufficient to bootstrap the registry correctly. For example to get images for clusters using the old kube-dns DNS provider:
> ./bundle-k8s-images.sh -k 1.10.11 -a 1.11 -f CoreDNS=false
The kubeadm image is publicly available on Docker Hub as rvesse/kubeadm with various tags covering 1.9 through 1.13. You can optionally build your own images using the other contents of this repository.
If you need to bundle additional images e.g. for your network overlay or other system services you can use the -e <image-ref> option as many times as you want to specify additional images to bundle e.g.
> ./bundle-k8s-images.sh -k 1.10.11 -a 1.11 -e quay.io/romana/agent:v2.0.2 -e quay.io/romana/listener:v2.0.2 -e quay.io/romana/daemon:v2.0.2
If you want to build your own images with Docker + kubeadm you can do so using the Dockerfile provided here. The provided buildImages.sh script will build images for all recent kubeadm versions. The script takes three arguments:
> ./buildImages.sh -r <repo> -n <image-name> -p
The <repo> and <image-name> arguments are used together with the versions to form a full image tag in the format <repo>/<name>:<version>.
The default versions which are built are hardcoded into the script as a Bash array. You can use the -v <version> option to build images for specified kubeadm versions. You can optionally specify -d to always include the default list of versions. If no versions are explicitly specified then the default list will be used.
If -p is given then the resulting images are also pushed to the selected <repo>.
You can use -l <version> to specify that a specific version should also be tagged as latest.