Script to migrate downstream rancher cluster to a new rancher URL.

migrate-cattle-agent-url.sh

#!/usr/bin/env bash
set -eu

# This script change the rancher manager URL (same rancher server) for downstream clusters.
# You need to access to the downstream cluster outside of rancher manager server, as you need to stop the cattle-agent deployment.
RANCHER_URL=https://rancher.mycompany.com

context=$(kubectl config current-context | cut -d'@' -f 2) # My context name is user@cluster
mkdir -p $context
secretName=$(kubectl get deploy cattle-cluster-agent -n cattle-system -o jsonpath="{.spec.template.spec.volumes[0].secret.secretName}")
secretUrlValue=$(kubectl get secret $secretName -n cattle-system -o jsonpath="{.data.url}" | base64 -d)
echo "> Context: $context, Secret Name: $secretName, Old URL: $secretUrlValue"

echo "> Saving secret..."
kubectl get secret $secretName -n cattle-system -o yaml > "$context/$secretName.orig.yaml";

# As the deployment is automatically restarted (webhook?), we need to scale to 0 twice
read -p "> Secret for $context saved. Press enter to scale deployment to 0."
kubectl scale deployment cattle-cluster-agent -n cattle-system --replicas 0
sleep 10
kubectl scale deployment cattle-cluster-agent -n cattle-system --replicas 0

read -p "> Deployment scaled to 0. Press enter to patch secret."
kubectl patch secret $secretName -n cattle-system --patch="{\"stringData\": { \"url\": \"${RANCHER_URL}\" }}"
kubectl get secret $secretName -n cattle-system -o yaml > "$context/$secretName.new.yaml";

read -p "> Secret $secretName patched. Press enter to set CATTLE_SERVER environment variable."
kubectl set env deployment/cattle-cluster-agent -n cattle-system "CATTLE_SERVER=${RANCHER_URL}"

read -p "> CATTLE_SERVER environment variable set. Press enter to scale deployment to 2."
kubectl scale deployment cattle-cluster-agent -n cattle-system --replicas 2