GKE Nodepool Add Labels Without overwriting existing labels

GKE has a feature to add node labels to all nodes in the nodepool. GKE will add the label to both the nodes already running in the cluster and also to newly added nodes.

You can use the feature like this:

gcloud container node-pools update my-node-pool \
  --cluster my-cluster --labels sam=test

That would add the label sam: test all your nodepools. The docs however do mention the following: "The label update overwrites any existing labels on the node pool. If the node pool has existing labels that you want to keep, you must include those labels along with any new labels that you want to add."

Well that's lame. But worry not. It's relatively easy to script this with a few lines of bash.

Create a file named gke-nodepool-add-label.sh with the following content:

#!/usr/bin/env bash

set -x

LABELS=$(gcloud container node-pools describe $POOL_NAME \
         --cluster $CLUSTER_NAME --format "get(config.labels)" | tr ";" ",")
echo "Current labels: $LABELS"
gcloud container node-pools update $POOL_NAME \
  --cluster $CLUSTER_NAME --node-labels="$LABELS,$NEW_LABEL"

Make the file executable:

chmod +x gke-nodepool-add-label.sh

Now you can run the script like this to add a label without overwriting existing labels:

./gke-nodepool-add-label.sh my-cluster my-nodepool sam=test