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GKE.md

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GKE

Install

If installing on a GKE cluster you don't have admin rights for, a ClusterRoleBinding may be needed to successfully deploy the controller in the final command. Replace with a valid email, and then deploy the cluster role binding:

USER_EMAIL=<your-email>
kubectl create clusterrolebinding $USER-cluster-admin-binding --clusterrole=cluster-admin --user=$USER_EMAIL

Private GKE clusters

If you are using a private GKE cluster, kubeseal won't be able to fetch the public key from the controller because there is firewall that prevents the control plane to talk directly to the nodes.

There are currently two workarounds:

Offline sealing

If you have the public key for your controller, you can seal secrets without talking to the controller. Normally kubeseal --fetch-cert can be used to obtain the certificate for later use, but in this case the firewall prevents us from doing it.

The controller outputs the certificate to the logs so you can copy paste it from there.

Once you have the cert this is how you seal secrets:

kubeseal --cert=cert.pem <secret.yaml

Control Plane to Node firewall

You are required to create a Control Plane to Node firewall rule to allow GKE to communicate to the kubeseal container endpoint port tcp/8080.

CLUSTER_NAME=foo-cluster
gcloud config set compute/zone your-zone-or-region

Get the CP_IPV4_CIDR.

CP_IPV4_CIDR=$(gcloud container clusters describe $CLUSTER_NAME \
  | grep "masterIpv4CidrBlock: " \
  | awk '{print $2}')

Get the NETWORK.

NETWORK=$(gcloud container clusters describe $CLUSTER_NAME \
  | grep "^network: " \
  | awk '{print $2}')

Get the NETWORK_TARGET_TAG.

NETWORK_TARGET_TAG=$(gcloud compute firewall-rules list \
  --filter network=$NETWORK --format json \
  | jq ".[] | select(.name | contains(\"$CLUSTER_NAME\"))" \
  | jq -r '.targetTags[0]' | head -1)

Check the values.

echo $CP_IPV4_CIDR $NETWORK $NETWORK_TARGET_TAG

# example output
10.0.0.0/28 foo-network gke-foo-cluster-c1ecba83-node

Create the firewall rule.

gcloud compute firewall-rules create gke-to-kubeseal-8080 \
  --network "$NETWORK" \
  --allow "tcp:8080" \
  --source-ranges "$CP_IPV4_CIDR" \
  --target-tags "$NETWORK_TARGET_TAG" \
  --priority 1000

Create the firewall rule to see the metrics

gcloud compute firewall-rules create gke-to-metrics-8081 \
  --network "$NETWORK" \
  --allow "tcp:8081" \
  --source-ranges "$CP_IPV4_CIDR" \
  --target-tags "$NETWORK_TARGET_TAG" \
  --priority 1000