Vault >= 1.15 is deployed
In the case of upgrading vault-k8s, it is recommended to have at least 5 units deployed and active to ensure minimal to no downtime.

Upgrade Procedure

Create a backup of your Vault data following this guide (in case anything goes wrong during the upgrade).
run juju refresh vault --channel=$VAULT_HIGHER_VERSION where VAULT_HIGHER_VERSION is any version higher than the one you have currently deployed.