Roll nodes in a Rancher 2 custom cluster using DigitalOcean droplets

roll-nodes-rancher2-custom-cluster.sh

#!/bin/bash
# Prereqs:
# * Rancher CLI configured to access the Rancher setup and an existing custom cluster with 3 nodes
# * doctl to create and delete droplets (https://github.com/digitalocean/doctl/releases)
# API token for Digital Ocean access
DIGITALOCEAN_TOKEN=""
# Prefix for newly created nodes
PREFIX="yourname"
# Existing custom cluster name used to roll nodes
CLUSTERNAME="custom"
# Change Docker version here if needed
IFS='' read -r -d '' TEMPLATE <<"EOF"
#!/bin/bash
curl https://releases.rancher.com/install-docker/20.10.sh | sh
EOF

# Check for doctl
if ! $(command -v doctl >/dev/null 2>&1); then
  echo "doctl is not installed. Exiting..."
  exit 1
fi

## Check cluster state
# Should have 3 nodes
echo "Waiting for node count 3 in cluster"
until [ $(rancher node ls --format='{{.Name}}' | wc -l) -eq 3 ]; do
  echo -n "."
done
echo "Found 3 nodes"

# Should be active
echo "Waiting for cluster $CLUSTERNAME to be active"
until rancher cluster ls | grep $CLUSTERNAME | grep -q active >/dev/null 2>&1; do
  echo -n "."
  sleep 10
done
echo "Cluster $CLUSTERNAME is active"


## Add a new node first
# Create add command
JOINCOMMAND=$(rancher cluster add-node ${CLUSTERNAME} --etcd --controlplane --worker | tail -1)

# Create userdata
echo "${TEMPLATE}" > "userdata_${CLUSTERNAME}.txt"
echo $JOINCOMMAND >> "userdata_${CLUSTERNAME}.txt"

RSTRING=$(tr -dc 'a-zA-Z0-9' < /dev/urandom | fold -w 10 | head -n 1 | tr '[:upper:]' '[:lower:]')
echo "Creating node ${PREFIX}-etcd-rotate-${RSTRING}"
doctl --access-token $DIGITALOCEAN_TOKEN compute droplet create "${PREFIX}-etcd-rotate-${RSTRING}" --size s-2vcpu-4gb --image ubuntu-16-04-x64 --region ams3 --user-data-file "userdata_${CLUSTERNAME}.txt" --wait >/dev/null 2>&1                                                  

echo "Waiting for node ${PREFIX}-etcd-rotate-${RSTRING} to register to cluster ${CLUSTERNAME}"
until rancher nodes | grep "${PREFIX}-etcd-rotate-${RSTRING}" >/dev/null 2>&1; do
  echo -n "."
  sleep 10
done
echo "Node ${PREFIX}-etcd-rotate-${RSTRING} is registered"

echo "Waiting for cluster $CLUSTERNAME to be active"
until rancher cluster ls | grep $CLUSTERNAME | grep -q active >/dev/null 2>&1; do
  echo -n "."
  sleep 10
done
echo "Cluster $CLUSTERNAME is active"


## Delete a node
# Select a node to delete
NODETODELETE=$(rancher node ls --format='{{.Name}}' | head -1)
echo "Selected ${NODETODELETE} to delete from cluster"

# Delete the node from Rancher
echo "Deleting ${NODETODELETE} from cluster"
rancher nodes delete $NODETODELETE

# Wait for cluster to be active
echo "Waiting for cluster $CLUSTERNAME to be active"
until rancher cluster ls | grep $CLUSTERNAME | grep -q active >/dev/null 2>&1; do
  echo -n "."
  sleep 20
done
echo "Cluster $CLUSTERNAME is active"

echo "Deleting ${NODETODELETE} from DigitalOcean"
doctl --access-token $DIGITALOCEAN_TOKEN compute droplet delete $NODETODELETE --force >/dev/null 2>&1