Description:
Running the GKE Metadata Server prevents workloads from accessing sensitive instance metadata and facilitates Workload Identity
Rationale:
Every node stores its metadata on a metadata server. Some of this metadata, such as kubelet credentials and the VM instance identity token, is sensitive and should not be exposed to a Kubernetes workload. Enabling the GKE Metadata server prevents pods (that are not running on the host network) from accessing this metadata and facilitates Workload Identity.
When unspecified, the default setting allows running pods to have full access to the node's underlying metadata server.
The GKE Metadata Server must be run when using Workload Identity. Because Workload Identity replaces the need to use Metadata Concealment, the two approaches are incompatible.
When the GKE Metadata Server and Workload Identity are enabled, unless the Pod is running on the host network, Pods cannot use the the Compute Engine default service account.
You may also need to modify workloads in order for them to use Workoad Identity as described within https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity.
The GKE Metadata Server requires Workload Identity to be enabled on a cluster. Modify the cluster to enable Workload Identity and enable the GKE Metadata Server.
Using Google Cloud Console
Using Command Line
gcloud beta container clusters update [CLUSTER_NAME]
--identity-namespace=[PROJECT_ID].svc.id.goog
Note that existing Node pools are unaffected. New Node pools default to '--workload-metadata-from-node=GKE_METADATA_SERVER'.
To modify an existing Node pool to enable GKE Metadata Server:
gcloud beta container node-pools update [NODEPOOL_NAME]
--cluster=[CLUSTER_NAME]
--workload-metadata-from-node=GKE_METADATA_SERVER
You may also need to modify workloads in order for them to use Workload Identity as described within https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity.