(kuberay-gke-bucket)=
# Configuring KubeRay to use Google Cloud Storage Buckets in GKE

If you are already familiar with Workload Identity in GKE, you can skip this document. The gist is that you need to specify a service account in each of the Ray pods after linking your Kubernetes service account to your Google Cloud service account. Otherwise, read on.

This example is an abridged version of the documentation at <https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity>. The full documentation is worth reading if you are interested in the details.

## Create a Kubernetes cluster on GKE

This example creates a minimal KubeRay cluster using GKE.

Run this and all following commands on your local machine or on the [Google Cloud Shell](https://cloud.google.com/shell). If running from your local machine, install the [Google Cloud SDK](https://cloud.google.com/sdk/docs/install).

```bash
PROJECT_ID=my-project-id # Replace my-project-id with your GCP project ID
CLUSTER_NAME=cloud-bucket-cluster
ZONE=us-west1-b

gcloud container clusters create $CLUSTER_NAME \
    --addons=RayOperator \
    --num-nodes=1 --min-nodes 0 --max-nodes 1 --enable-autoscaling \
    --zone=$ZONE --machine-type e2-standard-8 \
    --workload-pool=${PROJECT_ID}.svc.id.goog 
```


This command creates a Kubernetes cluster named `cloud-bucket-cluster` with one node in the `us-west1-b` zone. This example uses the `e2-standard-8` machine type, which has 8 vCPUs and 32 GB RAM.

For more information on how to find your project ID, see <https://support.google.com/googleapi/answer/7014113?hl=en> or <https://cloud.google.com/resource-manager/docs/creating-managing-projects>.

Now get credentials for the cluster to use with `kubectl`:

```bash
gcloud container clusters get-credentials $CLUSTER_NAME --zone $ZONE --project $PROJECT_ID
```

## Create a Kubernetes Service Account

```bash
NAMESPACE=default
KSA=my-ksa
kubectl create serviceaccount $KSA -n $NAMESPACE
```

## Configure the GCS Bucket

Create a GCS bucket that Ray uses as the remote filesystem.
```bash
BUCKET=my-bucket
gcloud storage buckets create gs://$BUCKET --uniform-bucket-level-access
```

Bind the `roles/storage.objectUser` role to the Kubernetes service account and bucket IAM policy.
See [Identifying projects](https://cloud.google.com/resource-manager/docs/creating-managing-projects#identifying_projects) to find your project ID and project number:
```bash
PROJECT_ID=<your project ID>
PROJECT_NUMBER=<your project number>
gcloud storage buckets add-iam-policy-binding gs://${BUCKET} --member "principal://iam.googleapis.com/projects/${PROJECT_NUMBER}/locations/global/workloadIdentityPools/${PROJECT_ID}.svc.id.goog/subject/ns/${NAMESPACE}/sa/${KSA}"  --role "roles/storage.objectUser"
```

See [Authenticate to Google Cloud APIs from GKE workloads](https://docs.cloud.google.com/kubernetes-engine/docs/how-to/workload-identity) for more details.

## Create a minimal RayCluster YAML manifest

You can download the RayCluster YAML manifest for this tutorial with `curl` as follows:

```bash
curl -LO https://raw.githubusercontent.com/ray-project/kuberay/v1.5.1/ray-operator/config/samples/ray-cluster.gke-bucket.yaml
```

The key parts are the following lines:

```yaml
      spec:
        serviceAccountName: my-ksa
        nodeSelector:
          iam.gke.io/gke-metadata-server-enabled: "true"
```

Include these lines in every pod spec of your Ray cluster. This example uses a single-node cluster (1 head node and 0 worker nodes) for simplicity.

## Create the RayCluster

```bash
kubectl apply -f ray-cluster.gke-bucket.yaml
```

## Test GCS bucket access from the RayCluster

Use `kubectl get pod` to get the name of the Ray head pod.  Then run the following command to get a shell in the Ray head pod:

```bash
kubectl exec -it raycluster-mini-head-xxxx -- /bin/bash
```

In the shell, run `pip install google-cloud-storage` to install the Google Cloud Storage Python client library.

(For production use cases, you will need to make sure `google-cloud-storage` is installed on every node of your cluster, or use `ray.init(runtime_env={"pip": ["google-cloud-storage"]})` to have the package installed as needed at runtime -- see <https://docs.ray.io/en/latest/ray-core/handling-dependencies.html#runtime-environments> for more details.)

Then run the following Python code to test access to the bucket:

```python
import ray
import os
from google.cloud import storage

GCP_GCS_BUCKET = "my-bucket"
GCP_GCS_FILE = "test_file.txt"

ray.init(address="auto")

@ray.remote
def check_gcs_read_write():
    client = storage.Client()
    bucket = client.bucket(GCP_GCS_BUCKET)
    blob = bucket.blob(GCP_GCS_FILE)

    # Write to the bucket
    blob.upload_from_string("Hello, Ray on GKE!")

    # Read from the bucket
    content = blob.download_as_text()

    return content

result = ray.get(check_gcs_read_write.remote())
print(result)
```

You should see the following output:

```text
Hello, Ray on GKE!
```