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Creating DNS records on a public hosted zone for AWS - External DNS Operator | Networking | OpenShift Container Platform 4.16
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Creating DNS records on AWS

Creating DNS records on an public hosted zone for AWS by using Red Hat External DNS Operator

You can create DNS records on a public hosted zone for AWS by using the Red Hat External DNS Operator. You can use the same instructions to create DNS records on a hosted zone for AWS GovCloud.

Procedure

  1. Check the user. The user must have access to the kube-system namespace. If you don’t have the credentials, as you can fetch the credentials from the kube-system namespace to use the cloud provider client:

    $ oc whoami
    Example output
    system:admin

  2. Fetch the values from aws-creds secret present in kube-system namespace.

    $ export AWS_ACCESS_KEY_ID=$(oc get secrets aws-creds -n kube-system  --template={{.data.aws_access_key_id}} | base64 -d)
$ export AWS_SECRET_ACCESS_KEY=$(oc get secrets aws-creds -n kube-system  --template={{.data.aws_secret_access_key}} | base64 -d)

  3. Get the routes to check the domain:

    $ oc get routes --all-namespaces | grep console
    Example output
    openshift-console          console             console-openshift-console.apps.testextdnsoperator.apacshift.support                       console             https   reencrypt/Redirect     None
openshift-console          downloads           downloads-openshift-console.apps.testextdnsoperator.apacshift.support                     downloads           http    edge/Redirect          None

  4. Get the list of dns zones to find the one which corresponds to the previously found route’s domain:

    $ aws route53 list-hosted-zones | grep testextdnsoperator.apacshift.support
    Example output
    HOSTEDZONES	terraform	/hostedzone/Z02355203TNN1XXXX1J6O	testextdnsoperator.apacshift.support.	5

  5. Create ExternalDNS resource for route source:

    $ cat <<EOF | oc create -f -
apiVersion: externaldns.olm.openshift.io/v1beta1
kind: ExternalDNS
metadata:
  name: sample-aws (1)
spec:
  domains:
  - filterType: Include   (2)
    matchType: Exact   (3)
    name: testextdnsoperator.apacshift.support (4)
  provider:
    type: AWS (5)
  source:  (6)
    type: OpenShiftRoute (7)
    openshiftRouteOptions:
      routerName: default (8)
EOF
    1 Defines the name of external DNS resource.
    2 By default all hosted zones are selected as potential targets. You can include a hosted zone that you need.
    3 The matching of the target zone’s domain has to be exact (as opposed to regular expression match).
    4 Specify the exact domain of the zone you want to update. The hostname of the routes must be subdomains of the specified domain.
    5 Defines the AWS Route53 DNS provider.
    6 Defines options for the source of DNS records.
    7 Defines OpenShift route resource as the source for the DNS records which gets created in the previously specified DNS provider.
    8 If the source is OpenShiftRoute, then you can pass the OpenShift Ingress Controller name. External DNS Operator selects the canonical hostname of that router as the target while creating CNAME record.

  6. Check the records created for OCP routes using the following command:

    $ aws route53 list-resource-record-sets --hosted-zone-id Z02355203TNN1XXXX1J6O --query "ResourceRecordSets[?Type == 'CNAME']" | grep console

Creating DNS records in a different AWS Account using a shared VPC

You can use the ExternalDNS Operator to create DNS records in a different AWS account using a shared Virtual Private Cloud (VPC). By using a shared VPC, an organization can connect resources from multiple projects to a common VPC network. Organizations can then use VPC sharing to use a single Route 53 instance across multiple AWS accounts.

Prerequisites

  • You have created two Amazon AWS accounts: one with a VPC and a Route 53 private hosted zone configured (Account A), and another for installing a cluster (Account B).

  • You have created an IAM Policy and IAM Role with the appropriate permissions in Account A for Account B to create DNS records in the Route 53 hosted zone of Account A.

  • You have installed a cluster in Account B into the existing VPC for Account A.

  • You have installed the ExternalDNS Operator in the cluster in Account B.

Procedure

  1. Get the Role ARN of the IAM Role that you created to allow Account B to access Account A’s Route 53 hosted zone by running the following command:

    $ aws --profile account-a iam get-role --role-name user-rol1 | head -1
    Example output
    ROLE	arn:aws:iam::1234567890123:role/user-rol1	2023-09-14T17:21:54+00:00	3600	/	AROA3SGB2ZRKRT5NISNJN	user-rol1

  2. Locate the private hosted zone to use with Account A’s credentials by running the following command:

    $ aws --profile account-a route53 list-hosted-zones | grep testextdnsoperator.apacshift.support
    Example output
    HOSTEDZONES	terraform	/hostedzone/Z02355203TNN1XXXX1J6O	testextdnsoperator.apacshift.support. 5

  3. Create the ExternalDNS object by running the following command:

    $ cat <<EOF | oc create -f -
apiVersion: externaldns.olm.openshift.io/v1beta1
kind: ExternalDNS
metadata:
  name: sample-aws
spec:
  domains:
  - filterType: Include
    matchType: Exact
    name: testextdnsoperator.apacshift.support
  provider:
    type: AWS
    aws:
      assumeRole:
        arn: arn:aws:iam::12345678901234:role/user-rol1 (1)
  source:
    type: OpenShiftRoute
    openshiftRouteOptions:
      routerName: default
EOF
    1 Specify the Role ARN to have DNS records created in Account A.

  4. Check the records created for OpenShift Container Platform (OCP) routes by using the following command:

    $ aws --profile account-a route53 list-resource-record-sets --hosted-zone-id Z02355203TNN1XXXX1J6O --query "ResourceRecordSets[?Type == 'CNAME']" | grep console-openshift-console