Deploy ExternalDNS

In this section you will configure and deploy ExternalDNS using Workload Identity to provide it with permissions to manage DNS records on Google Cloud DNS.

Note

If you are not going to use Cloud DNS to assign an FQDN to your Load Balancer, you can use Cloud Endpoints or edit /etc/hosts manually. You will find instructions for the aforemetioned alternatives in the guide that follows. You may proceed to the What’s Next section.

See also

• Official docs for deploying ExternalDNS on GKE.

What You’ll Need

• A configured management environment.
• Your clone of the Arrikto GitOps repository.
• An existing GKE cluster.
• An existing Cloud DNS managed zone.

Procedure

1. Go to your GitOps repository, inside your rok-tools management environment:

   

   root@rok-tools:~# cd ~/ops/deployments

2. Specify the name for the service account for ExternalDNS:

   

   root@rok-tools:~/ops/deployments# export EDNS_SERVICE_ACCOUNT_NAME=<EDNS_SERVICE_ACCOUNT_NAME>

   Replace <EDNS_SERVICE_ACCOUNT_NAME> with your desired service account name. For example:

   

   root@rok-tools:~/ops/deployments# export EDNS_SERVICE_ACCOUNT_NAME=external-dns

   Note

   This must be between 6 and 30 characters, and can contain lowercase alphanumeric characters and dashes.

3. Create the service account for ExternalDNS:

   

   root@rok-tools:~/ops/deployments# gcloud iam service-accounts create ${EDNS_SERVICE_ACCOUNT_NAME?} \ > --display-name=${EDNS_SERVICE_ACCOUNT_NAME?}

4. Specify the service account email:

   

   root@rok-tools:~/ops/deployments# export EDNS_SERVICE_ACCOUNT=${EDNS_SERVICE_ACCOUNT_NAME?}@${PROJECT_ID?}.iam.gserviceaccount.com

5. Bind the service account to the DNS admin role:

   

   root@rok-tools:~/ops/deployments# gcloud projects add-iam-policy-binding ${PROJECT_ID?} \ > --member="serviceAccount:${EDNS_SERVICE_ACCOUNT?}" \ > --role=roles/dns.admin \ > --condition=None

6. Link the Google Cloud service account to the Kubernetes service account that ExternalDNS will run under, that is the external-dns service account in the default namespace:

   

   root@rok-tools:~/ops/deployments# gcloud iam service-accounts add-iam-policy-binding ${EDNS_SERVICE_ACCOUNT?} \ > --member="serviceAccount:${PROJECT_ID?}.svc.id.goog[default/external-dns]" \ > --role=roles/iam.workloadIdentityUser

7. Edit rok/external-dns/overlays/deploy/kustomization.yaml and enable only the sa-gcp and deploy-gcp patches:

   

   patches: #- path: patches/sa.yaml - path: patches/sa-gcp.yaml #- target: # kind: Deployment # name: external-dns # path: patches/deploy.yaml - target: kind: Deployment name: external-dns path: patches/deploy-gcp.yaml

8. Retrieve your domain. Copy the output to your clipboard, as you are going to use this value in the next step:

   

   root@rok-tools:~/ops/deployments# echo ${DOMAIN?} apps.example.com

9. Edit rok/external-dns/overlays/deploy/patches/deploy-gcp.yaml and set --domain-filter to your domain:

   

   ... - --domain-filter=apps.example.com # <-- Update this line with you DOMAIN

10. Retrieve the ID of your Google project. Copy the output to your clipboard, as you are going to use this value in the next step:

    

    root@rok-tools:~/ops/deployments# echo ${PROJECT_ID?} myproject

11. Edit rok/external-dns/overlays/deploy/patches/deploy-gcp.yaml and set --google-project to your project ID:

    

    ... - --google-project=myproject # <-- Update this line with your PROJECT_ID

12. Define the owner ID for ExternalDNS:

    

    root@rok-tools:~/ops/deployments# export EDNS_OWNER=rok-${ZONE?}-${GKE_CLUSTER?}

13. Retrieve the owner ID for ExternalDNS you defined in the previous step. Copy the output to your clipboard, as you are going to use this value in the next step:

    

    root@rok-tools:~/ops/deployments# echo ${EDNS_OWNER?} rok-us-east1-b-arrikto-cluster

14. Edit rok/external-dns/overlays/deploy/patches/deploy-gcp.yaml and set --txt-owner-id to the owner ID:

    

    ... - --txt-owner-id=rok-us-east1-b-arrikto-cluster # <-- Update this line with your EDNS_OWNER

15. Retrieve the email of your Google Cloud service account for ExternalDNS. Copy the output to your clipboard, as you are going to use this value in the next step:

    

    root@rok-tools:~/ops/deployments# echo ${EDNS_SERVICE_ACCOUNT?} external-dns@myproject.iam.gserviceaccount.com

16. Edit rok/external-dns/overlays/deploy/patches/sa-gcp.yaml and set the Workload Identity related annotation to the email of your Google Cloud service account for ExternalDNS:

    

    iam.gke.io/gcp-service-account: external-dns@myproject.iam.gserviceaccount.com # <-- Update this line with your EDNS_SERVICE_ACCOUNT

17. Commit your changes:

    

    root@rok-tools:~/ops/deployments# git commit -am "Deploy ExternalDNS on GKE"

18. Deploy ExternalDNS:

    

    root@rok-tools:~/ops/deployments# rok-deploy --apply rok/external-dns/overlays/deploy

Verify

1. Verify that the ExternalDNS deployment is up-and-running. Verify field READY is 1/1:

   

   root@rok-tools:~/ops/deployments# kubectl get deploy/external-dns NAME READY UP-TO-DATE AVAILABLE AGE external-dns 1/1 1 1 1m

Summary

You have successfully deployed ExternalDNS and allowed it to access your Cloud DNS managed zone.

What’s Next

The next step is to assign a proper FQDN to your Load Balancer IP address.

• Assign FQDN to GCLB