external-dns - Automate creation of domain names based on ingress ¶

external-dns is a popular option with very wide support for DNS management on kubernetes. Typically, when you create a ingress with subdomain in host field, you would need to add additional DNS entry in your DNS provider (like Route53 in AWS) for this subdomain pointing to your ingress controller. External DNS automates these entry creations.

Steps to setup pre-requisits, install and use External-DNS ¶

Create hosted zone in Route53 (if you do not have it already). You can also make use of free domain name providers like freenom or dot.tk if you want a throwaway domain.
Add a new IAM policy which allows update the hosted zone. Create IAM policy with below content. You should update hostedzone/* to hostedzone/<your hosted zone id> to make it more restrictive.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "route53:ChangeResourceRecordSets"
      ],
      "Resource": [
        "arn:aws:route53:::hostedzone/*"
      ]
    },
    {
      "Effect": "Allow",
      "Action": [
        "route53:ListHostedZones",
        "route53:ListResourceRecordSets"
      ],
      "Resource": [
        "*"
      ]
    }
  ]
}

Associate this policy with instance profile of KOPS works nodes KOPS allows you to add below liens in your cluster spec to add this above policy to default node instance profile. Make sure you replace the ARN with the ARN of the policy which you defined in your AWS account.

spec:
  externalPolicies:
     node:
     - arn:aws:iam::<youraccount>:policy/<yourpolicyname>

Deploy ingress-controller helm-chart, if not already. (Refer Deploy page for details)
Deploy external-dns helm-chart. Replace HOSTED_ZONE_ID and HOSTED_ZONE_NAME with your Route53 hosted zone details.

helm upgrade --install external-dns \
  --set provider=aws \
  --set aws.zoneType=public \
  --set txtOwnerId=HOSTED_ZONE_ID \
  --set domainFilters[0]=HOSTED_ZONE_NAME \
  bitnami/external-dns

Test the setup by deploying a sample app with ingress (podinfo). Refer Deploy page for details. If you notice the podinfo.yaml in the deploy directory, you will see hostname added there. If the setup is correctly done, after the deployment, in about 2 minutes, the corresponding entry in Route53 will be created automatically.

FIXME - add screenshots

References: ¶

https://github.com/kubernetes-sigs/external-dns/blob/master/docs/tutorials/aws.md
https://artifacthub.io/packages/helm/bitnami/external-dns
https://kops.sigs.k8s.io/iam_roles/#adding-external-policies