Upgrading

To upgrade Kubernetes or an add-on in a kURL cluster, generate a new installer script and run it on any primary in the cluster.

Kubernetes

If the install script detects an upgrade of Kubernetes is required, it will first drain and upgrade the primary where the script is running. Then if there are any remote primaries to upgrade, the script will drain each sequentially and print out a script that must be run on that node. The script will detect when Kubernetes has been upgraded on the remote node and proceed to drain the next node. After upgrading all primaries the same operation will be performed sequentially on all remote secondaries.

The install script supports upgrading at most two minor versions of Kubernetes. When upgrading two minor versions, the skipped minor version will be installed before proceeding to the desired version. For example, it's possible to upgrade directly from Kubernetes 1.17 to 1.19 but the install script will complete the installation of 1.18 before proceeding to 1.19.

Container Runtimes

Existing versions of docker and containerd will never be upgraded by the install script.

Airgap

Because upgraded components may have pods scheduled on any node in the cluster, images must be pre-loaded on every node prior to running the updated installer. After downloading and extracting the airgap bundle to every node in the cluster, run this script to ensure all required images are available:

cat tasks.sh | sudo bash -s load-images

The install script will also perform a check for required images and prompt the user to run this command if any are missing.