Customize DNS

Customize DNS configurations for Verrazzano system and application endpoints

Verrazzano supports three DNS choices for Verrazzano services and applications:

Free wildcard DNS services (nip.io and sslip.io)
Oracle Cloud Infrastructure DNS managed by Verrazzano
Custom (user-managed) DNS

How Verrazzano constructs a DNS domain

Regardless of which DNS management you use, the value in the spec.environmentName field in your installation will be prepended to the configured domain in the spec.components.dns section of the custom resource, to form the full DNS domain name used to access Verrazzano endpoints.

For example, if spec.environmentName is set to sales and the domain is configured in spec.components.dns as us.example.com, Verrazzano will create sales.us.example.com as the DNS domain for the installation.

Wildcard DNS Services

Verrazzano can be configured to use either the nip.io or sslip.io free wildcard DNS services. When queried with a host name with an embedded IP address, wildcard DNS services return that IP address.

For example, using the nip.io service, the following DNS names all map to the IP address 10.0.0.1:

10.0.0.1.nip.io
app.10.0.0.1.nip.io
customer1.app.10.0.0.1.nip.io

To configure Verrazzano to use one of these services, set the spec.wildcard.domain field in the Verrazzano custom resource to either nip.io or sslip.io; the default is nip.io.

For example, the following configuration uses sslip.io, instead of nip.io, for wildcard DNS with a dev installation profile.

apiVersion: install.verrazzano.io/v1beta1
kind: Verrazzano
metadata:
  name: example-verrazzano
spec:
  profile: dev
  components:
    dns:
      wildcard:
        domain: sslip.io

Oracle Cloud Infrastructure DNS

Verrazzano can directly manage records in Oracle Oracle Cloud Infrastructure DNS when configured to use the spec.components.dns.oci field. This is achieved through the External DNS Service, which is a component that is conditionally installed when Oracle Cloud Infrastructure DNS is configured for DNS management in Verrazzano.

Prerequisites

The following prerequisites must be met before using Oracle Cloud Infrastructure DNS with Verrazzano:

You must have control of a DNS domain.
You must have an Oracle Cloud Infrastructure DNS Service Zone that is configured to manage records for that domain. Verrazzano also supports the use of both GLOBAL and PRIVATE Oracle Cloud Infrastructure DNS zones.

A DNS Service Zone is a distinct portion of a domain namespace. You must ensure that the zone is appropriately associated with a parent domain. For example, an appropriate zone name for parent domain example.com is us.example.com.

To create an Oracle Cloud Infrastructure DNS zone using the Oracle Cloud Infrastructure CLI:
```
$ oci dns zone create \
    -c <compartment ocid> \
    --name <zone-name-prefix>.example.com \
    --zone-type PRIMARY
```
To create an Oracle Cloud Infrastructure DNS zone using the Oracle Cloud Infrastructure Console, see Managing DNS Service Zones.
You must have a valid Oracle Cloud Infrastructure API signing key that can be used to communicate with Oracle Cloud Infrastructure DNS in your tenancy.

For example, you can create an API signing key using the Oracle Cloud Infrastructure CLI.
```
  $ oci setup keys --key-name myapikey
  Enter a passphrase for your private key (empty for no passphrase):
  Public key written to: /Users/jdoe/.oci/myapikey_public.pem
  Private key written to: /Users/jdoe/.oci/myapikey.pem
  Public key fingerprint: 39:08:44:69:9f:f5:73:86:7a:46:d8:ad:34:4f:95:29
```
If you haven’t already uploaded your API signing public key through the console, follow the instructions in this section, How to upload the public key.

After the key pair has been created, you must upload the public key to your account in your Oracle Cloud Infrastructure tenancy. For details, see the Oracle Cloud Infrastructure documentation, Required Keys and OCIDs.

Create an Oracle Cloud Infrastructure API secret in the target cluster

To communicate with Oracle Cloud Infrastructure DNS to manage DNS records, Verrazzano needs to be made aware of the necessary API credentials.
A generic Kubernetes secret must be created in the cluster’s verrazzano-install namespace with the required credentials. That secret must then be referenced by the custom resource that is used to install Verrazzano.

After you have an Oracle Cloud Infrastructure API key ready for use, create a YAML file, oci.yaml, with the API credentials in the form:

auth:
  region: <oci-region>
  tenancy: <oci-tenancy-ocid>
  user: <oci-user-ocid>
  key: |
    <oci-api-private-key-file-contents>
  fingerprint: <oci-api-private-key-fingerprint>

This information typically can be found in your Oracle Cloud Infrastructure CLI config file or in the Oracle Cloud Infrastructure Console. The <oci-api-private-key-file-contents> contents are the PEM-encoded contents of the key_file value within the Oracle Cloud Infrastructure CLI configuration profile.

For example, your oci.yaml file will look similar to the following:

auth:
  region: us-ashburn-1
  tenancy: ocid1.tenancy.oc1.....
  user: ocid1.user.oc1.....
  key: |
    -----BEGIN RSA PRIVATE KEY-----
    ...
    -----END RSA PRIVATE KEY-----
  fingerprint: 12:d3:4c:gh:fd:9e:27:g8:b9:0d:9f:00:22:33:c3:gg

Verrazzano also supports the use of instance principals to communicate with Oracle Cloud Infrastructure in order to create or update Oracle Cloud Infrastructure DNS records. Instance principals require some prerequisites that can be found here.

When using instance principals, your oci.yaml file will look as follows:

auth:
  authtype: instance_principal

Then, you can create a generic Kubernetes secret in the cluster’s verrazzano-install namespace using kubectl.

$ kubectl create secret generic -n verrazzano-install <secret-name> --from-file=<path-to-oci-yaml-file>

For example, to create a secret named oci from a file oci.yaml, do the following:

$ kubectl create secret generic -n verrazzano-install oci --from-file=oci.yaml

This secret will later be referenced from the Verrazzano custom resource used during installation.

Use a Verrazzano helper script to create an Oracle Cloud Infrastructure secret

Verrazzano also provides a helper script to create the necessary Kubernetes secret based on your Oracle Cloud Infrastructure CLI configuration file, assuming that you have the Oracle Cloud Infrastructure CLI installed and a valid Oracle Cloud Infrastructure CLI profile with the required API key information. The script create_oci_config_secret.sh reads your Oracle Cloud Infrastructure CLI configuration file to create the secret.

First, download the create_oci_config_secret.sh script.

$ curl \
    -o ./create_oci_config_secret.sh \
    https://raw.githubusercontent.com/verrazzano/verrazzano/v1.7.2/platform-operator/scripts/install/create_oci_config_secret.sh

Next, set your KUBECONFIG environment variable to point to your cluster and run create_oci_config_secret.sh -h to display the script options.

$ chmod +x create_oci_config_secret.sh
$ export KUBECONFIG=<kubeconfig-file>
$ ./create_oci_config_secret.sh  -h
usage: ./create_oci_config_secret.sh [-o oci_config_file] [-s config_file_section]
  -o oci_config_file         The full path to the Oracle Cloud Infrastructure configuration file (default ~/.oci/config)
  -s config_file_section     The properties section within the Oracle Cloud Infrastructure configuration file.  Default is DEFAULT
  -k secret_name             The secret name containing the Oracle Cloud Infrastructure configuration.  Default is oci
  -c context_name            The kubectl context to use
  -a auth_type               The auth_type to be used to access Oracle Cloud Infrastructure. Valid values are user_principal/instance_principal. Default is user_principal.
  -h                         Help

For example, to have the script create the YAML file using your [DEFAULT] Oracle Cloud Infrastructure CLI profile and then create a Kubernetes secret named oci, you can run the script with no arguments, as follows:

$ ./create_oci_config_secret.sh
secret/oci created

The following example creates a secret myoci using an Oracle Cloud Infrastructure CLI profile named [dev].

$ ./create_oci_config_secret.sh -s dev -k myoci
secret/myoci created

When using instance principals, all other parameters will be ignored automatically. The following example creates a secret myoci using Oracle Cloud Infrastructure instance principal.

$ ./create_oci_config_secret.sh -a instance_principal
secret/myoci created

Installation

After the Oracle Cloud Infrastructure API secret is created, create a Verrazzano custom resource for the installation that is configured to use Oracle Cloud Infrastructure DNS and reference the secret you created.

As a starting point, download the sample Verrazzano custom resource install-oci.yaml file for Oracle Cloud Infrastructure DNS.

$ curl \
    -o ./install-oci.yaml \
    https://raw.githubusercontent.com/verrazzano/verrazzano/v1.7.2/platform-operator/config/samples/install-oci.yaml

Edit the install-oci.yaml file to provide values for the following configuration settings in the custom resource spec:

spec.environmentName
spec.components.dns.oci.ociConfigSecret
spec.components.dns.oci.dnsZoneCompartmentOCID
spec.components.dns.oci.dnsZoneOCID
spec.components.dns.oci.dnsZoneName
spec.components.dns.oci.dnsScope

The field spec.components.dns.oci.ociConfigSecret should reference the secret created earlier. For details on the Oracle Cloud Infrastructure DNS configuration settings, see spec.components.dns.oci.

For example, a custom resource for a prod installation profile using Oracle Cloud Infrastructure DNS might look as follows, yielding a domain of myenv.example.com (Oracle Cloud Infrastructure identifiers redacted):

apiVersion: install.verrazzano.io/v1beta1
kind: Verrazzano
metadata:
  name: example-verrazzano
spec:
  profile: prod
  environmentName: myenv
  components:
    dns:
      oci:
        ociConfigSecret: oci
        dnsZoneCompartmentOCID: ocid1.compartment.oc1..compartment-ocid
        dnsZoneOCID: ocid1.dns-zone.oc1..zone-ocid
        dnsZoneName: example.com

If using a private DNS zone, then the same prod installation profile using Oracle Cloud Infrastructure DNS will look as follows:

apiVersion: install.verrazzano.io/v1beta1
kind: Verrazzano
metadata:
  name: my-verrazzano
spec:
  profile: prod
  environmentName: myenv
  components:
    dns:
      oci:
        ociConfigSecret: oci
        dnsZoneCompartmentOCID: ocid1.compartment.oc1..compartment-ocid
        dnsZoneOCID: ocid1.dns-zone.oc1..zone-ocid
        dnsZoneName: example.com
        dnsScope: PRIVATE

After the custom resource is ready, apply it using kubectl apply -f <path-to-custom-resource-file>.

Custom DNS

You can specify your own externally managed, custom DNS domain. In this scenario, you manage your own DNS domain and all DNS records in that domain.

An externally managed DNS domain is specified in the spec.components.dns.external.suffix field of the Verrazzano custom resource.

When using an externally managed DNS domain, you are responsible for:

Configuring A records for Verrazzano ingress points (load balancers)
Configuring CNAME records for host names in the domain that point to the A records, as needed

The Verrazzano installer searches the DNS zone you provide for two specific A records.
These are used to configure the cluster and should refer to external addresses of the load balancers provisioned by the user.

The A records need to be created manually.

Record	Use
`ingress-mgmt`	Set as the `.spec.externalIPs` value of the `ingress-controller-nginx-ingress-controller` service.
`ingress-verrazzano`	Set as the `.spec.externalIPs` value of the `istio-ingressgateway` service.

For example, if spec.environmentName is set to myenv, and spec.components.dns.external.suffix is set to example.com, the A records would need to be set up as follows:

198.51.100.10                                   A       ingress-mgmt.myenv.example.com.
203.0.113.10                                    A       ingress-verrazzano.myenv.example.com.

This example assumes that load balancers exist for ingress-mgmt on 198.51.100.10 and for ingress-verrazzano on 203.0.113.10.

For a more complete example, see the documentation for setting up Verrazzano on the Oracle Cloud Native Environment Platform.

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