Upgrade CDK

upgrade-cdk automates the CDK (Charmed Distribution of Kubernetes) upgrade workflow using the Jubilant library.

Features:

• Charm refresh – refresh charms from a CSV manifest in the correct order
• Config management – validate and apply application configuration
• State monitoring – wait for units to reach active/idle after each step
• ETCD backup – snapshot the etcd cluster before any upgrade begins
• Sequential unit upgrades – upgrade control-plane and worker units one at a time with interactive confirmation
• Blue-green worker migration – replace workers one-by-one with new machines using full cordon + drain + remove lifecycle

Usage:

upgrade-cdk <controller>:<model> <channel>

upgrade-cdk <controller>:<model> <channel> [charms.csv]

upgrade-cdk <controller>:<model> <channel> --bluegreen

upgrade-cdk <controller>:<model> <channel> [charms.csv] --bluegreen --parallel 3

When no CSV file is given the bundled charms.csv is used.

Why classic confinement? upgrade-cdk requires unrestricted filesystem access to:

• Juju credentials at ~/.local/share/juju (written by the juju snap)
• Kubernetes config at ~/.kube/config or $KUBECONFIG
• SSH keys used for juju scp operations
• The juju snap binary at /snap/bin/juju