How to configure external-dns with Microsoft DNS in TKG 1.3 (plus Harbor and Contour)

External-DNS is an open source project that is newly included in TKG 1.3. External-DNS synchronizes exposed Kubernetes Services and Ingresses with DNS providers. TKG 1.3 uses external-DNS to assist with service discovery as it will automatically create DNS records for httpproxy resources created via Contour in TKG. AWS (Route53), Azure, and RFC2136 (BIND) are currently supported but I’m going to focus on RFC2136 since this is what is needed to work with Microsoft DNS.

Configuring external-DNS to work with Microsoft DNS is documented on GitHub but since we need to deploy it via an extension/app, there are a few tweaks we need to make to the documented procedure.

Check DNS settings

The first thing I found that I needed to do was to check my DNS settings. There are two that you need to be sure are set appropriately or it’s not going to work.

The first is the Zone Transfers setting. By default, this is not enabled at all so I set it to allow transfers To any server.

The second setting is Dynamic Updates. Currently, external-DNS only supports insecure updates to Microsoft DNS so I had to change this setting to Nonsecure and secure.

Deploy the extension, kapp and cert-manager framework to a workload cluster

This is nearly identical to the process I documented in an earlier post, Working with TKG Extensions and Shared Services in TKG 1.2, so I won’t got into too much detail here. You obviously need to have already deployed a TKG 1.3 management cluster and a workload cluster, and switched your context to the workload cluster. I have a writeup on deploying TKG 1.3 at Installing Tanzu Kubernetes Grid 1.3 on vSphere with NSX Advanced Load Balancer if you need to start at the beginning.

Deploy the extension manager:

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/tmc-extension-manager.yaml

namespace/vmware-system-tmc created
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
customresourcedefinition.apiextensions.k8s.io/agents.clusters.tmc.cloud.vmware.com created
customresourcedefinition.apiextensions.k8s.io/extensionconfigs.intents.tmc.cloud.vmware.com created
customresourcedefinition.apiextensions.k8s.io/extensionintegrations.clusters.tmc.cloud.vmware.com created
customresourcedefinition.apiextensions.k8s.io/extensionresourceowners.clusters.tmc.cloud.vmware.com created
customresourcedefinition.apiextensions.k8s.io/extensions.clusters.tmc.cloud.vmware.com created
serviceaccount/extension-manager created
clusterrole.rbac.authorization.k8s.io/extension-manager-role created
clusterrolebinding.rbac.authorization.k8s.io/extension-manager-rolebinding created
service/extension-manager-service created
deployment.apps/extension-manager created

Deploy the kapp controller:

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/kapp-controller.yaml

Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
namespace/tkg-system configured
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
serviceaccount/kapp-controller-sa configured
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
customresourcedefinition.apiextensions.k8s.io/apps.kappctrl.k14s.io configured
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
deployment.apps/kapp-controller configured
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
clusterrole.rbac.authorization.k8s.io/kapp-controller-cluster-role configured
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
clusterrolebinding.rbac.authorization.k8s.io/kapp-controller-cluster-role-binding configured

Deploy cert-manager:

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/cert-manager/

namespace/cert-manager created
Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
customresourcedefinition.apiextensions.k8s.io/certificaterequests.cert-manager.io created
customresourcedefinition.apiextensions.k8s.io/certificates.cert-manager.io created
customresourcedefinition.apiextensions.k8s.io/challenges.acme.cert-manager.io created
customresourcedefinition.apiextensions.k8s.io/clusterissuers.cert-manager.io created
customresourcedefinition.apiextensions.k8s.io/issuers.cert-manager.io created
customresourcedefinition.apiextensions.k8s.io/orders.acme.cert-manager.io created
serviceaccount/cert-manager-cainjector created
serviceaccount/cert-manager created
serviceaccount/cert-manager-webhook created
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRole is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRole
clusterrole.rbac.authorization.k8s.io/cert-manager-cainjector created
clusterrole.rbac.authorization.k8s.io/cert-manager-controller-issuers created
clusterrole.rbac.authorization.k8s.io/cert-manager-controller-clusterissuers created
clusterrole.rbac.authorization.k8s.io/cert-manager-controller-certificates created
clusterrole.rbac.authorization.k8s.io/cert-manager-controller-orders created
clusterrole.rbac.authorization.k8s.io/cert-manager-controller-challenges created
clusterrole.rbac.authorization.k8s.io/cert-manager-controller-ingress-shim created
clusterrole.rbac.authorization.k8s.io/cert-manager-view created
clusterrole.rbac.authorization.k8s.io/cert-manager-edit created
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRoleBinding
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-cainjector created
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-controller-issuers created
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-controller-clusterissuers created
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-controller-certificates created
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-controller-orders created
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-controller-challenges created
clusterrolebinding.rbac.authorization.k8s.io/cert-manager-controller-ingress-shim created
Warning: rbac.authorization.k8s.io/v1beta1 Role is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 Role
role.rbac.authorization.k8s.io/cert-manager-cainjector:leaderelection created
role.rbac.authorization.k8s.io/cert-manager:leaderelection created
role.rbac.authorization.k8s.io/cert-manager-webhook:dynamic-serving created
Warning: rbac.authorization.k8s.io/v1beta1 RoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 RoleBinding
rolebinding.rbac.authorization.k8s.io/cert-manager-cainjector:leaderelection created
rolebinding.rbac.authorization.k8s.io/cert-manager:leaderelection created
rolebinding.rbac.authorization.k8s.io/cert-manager-webhook:dynamic-serving created
service/cert-manager created
service/cert-manager-webhook created
deployment.apps/cert-manager-cainjector created
deployment.apps/cert-manager created
deployment.apps/cert-manager-webhook created
Warning: admissionregistration.k8s.io/v1beta1 MutatingWebhookConfiguration is deprecated in v1.16+, unavailable in v1.22+; use admissionregistration.k8s.io/v1 MutatingWebhookConfiguration
mutatingwebhookconfiguration.admissionregistration.k8s.io/cert-manager-webhook created
Warning: admissionregistration.k8s.io/v1beta1 ValidatingWebhookConfiguration is deprecated in v1.16+, unavailable in v1.22+; use admissionregistration.k8s.io/v1 ValidatingWebhookConfiguration
validatingwebhookconfiguration.admissionregistration.k8s.io/cert-manager-webhook created

Configure and deploy external-DNS

Similar to other extensions in earlier versions of TKG, the first thing to do is to create the namespace and roles.

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/service-discovery/external-dns/namespace-role.yaml

namespace/tanzu-system-service-discovery created
serviceaccount/external-dns-extension-sa created
role.rbac.authorization.k8s.io/external-dns-extension-role created
rolebinding.rbac.authorization.k8s.io/tanzu-system-service-discovery-rolebinding created
clusterrole.rbac.authorization.k8s.io/external-dns-extension-cluster-role created
clusterrolebinding.rbac.authorization.k8s.io/external-dns-extension-cluster-rolebinding created

Next we need to create a copy of the default data-values file so that we can customize it. There are a few different ones present for this extension but I’m working with the external-dns-data-values-rfc2136-with-contour.yaml.example file.

cp tkg-extensions-v1.3.0+vmware.1/extensions/service-discovery/external-dns/external-dns-data-values-rfc2136-with-contour.yaml.example external-dns-data-values-rfc2136-with-contour.yaml
@data/values
 #@overlay/match-child-defaults missing_ok=True
 externalDns:
   image:
     repository: projects.registry.vmware.com/tkg
   deployment:
     #@overlay/replace
     args:
     - --txt-owner-id=k8s
     - --provider=rfc2136
     - --rfc2136-host=192.168.0.1 #! IP of RFC2136 compatible dns server
     - --rfc2136-port=53
     - --rfc2136-zone=my-zone.example.org #! zone where services are deployed
     - --rfc2136-tsig-secret=REPLACE_ME_WITH_TSIG_SECRET #! TSIG key authorized to update the DNS server
     - --rfc2136-tsig-secret-alg=hmac-sha256
     - --rfc2136-tsig-keyname=externaldns-key
     - --rfc2136-tsig-axfr
     - --source=service
     - --source=contour-httpproxy #! export contour HTTPProxy objs
     - --domain-filter=my-zone.example.org #! zone where services are deployed

I’ll be making a number of changes to this file to allow for external DNS to communicate with my Microsoft DNS implementation.

  • setting the rfc2136-host value to controlcenter.corp.tanzu, the FQDN of my AD/DNS server
  • setting the rfc2136-zone value to corp.tanzu, the DNS zone name
  • adding the rfc-2136-insecure flag to allow external-dns to communicate without authentication
  • removing the rfc2136-tsig-secret, rfc2136-tsig-secret-alg and rfc2136-tsig-keyname flags as they won’t be needed
  • setting the domain-filter value to corp.tanzu, the DNS zone name
#@data/values
#@overlay/match-child-defaults missing_ok=True
---
externalDns:
  image:
    repository: projects.registry.vmware.com/tkg
  deployment:
    #@overlay/replace
    args:
    - --txt-owner-id=k8s
    - --provider=rfc2136
    - --rfc2136-host=controlcenter.corp.tanzu
    - --rfc2136-port=53
    - --rfc2136-zone=corp.tanzu
    - --rfc2136-insecure
    - --rfc2136-tsig-axfr
    - --source=service
    - --source=contour-httpproxy
    - --domain-filter=corp.tanzu

One thing to note here is that the default setting for source is contour-httpproxy…this means that external-dns is only going to be monitoring for httproxy resources. You could configure this for something else if you’re not using Contour.

With these changes in place, we can use this file to create a secret that will be used for the external-dns condiguration.

kubectl create secret generic external-dns-data-values --from-file=values.yaml=external-dns-data-values-rfc2136-with-contour.yaml -n tanzu-system-service-discovery

secret/external-dns-data-values created

And now we can deploy the external-dns extension, which will in turn create all other needed components.

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/service-discovery/external-dns/external-dns-extension.yaml

extension.clusters.tmc.cloud.vmware.com/external-dns created

We can check on the status of this extension from a high level by inspecting the external-dns app.

kubectl -n tanzu-system-service-discovery get app external-dns -o yaml

  inspect:
    exitCode: 0
    stdout: |-
      Target cluster 'https://100.64.0.1:443'
      07:26:34PM: debug: Resources: Ignoring group version: schema.GroupVersionResource{Group:"stats.antrea.tanzu.vmware.com", Version:"v1alpha1", Resource:"antreanetworkpolicystats"}
      07:26:34PM: debug: Resources: Ignoring group version: schema.GroupVersionResource{Group:"stats.antrea.tanzu.vmware.com", Version:"v1alpha1", Resource:"networkpolicystats"}
      Resources in app 'external-dns-ctrl'
      Namespace                       Name                            Kind                Owner    Conds.  Rs  Ri  Age
      (cluster)                       external-dns                    ClusterRole         kapp     -       ok  -   11s
      ^                               external-dns-viewer             ClusterRoleBinding  kapp     -       ok  -   11s
      ^                               tanzu-system-service-discovery  Namespace           kapp     -       ok  -   2m
      tanzu-system-service-discovery  external-dns                    Deployment          kapp     2/2 t   ok  -   11s
      ^                               external-dns                    ServiceAccount      kapp     -       ok  -   11s
      ^                               external-dns-5f7f698b8d         ReplicaSet          cluster  -       ok  -   11s
      ^                               external-dns-5f7f698b8d-q52bn   Pod                 cluster  4/4 t   ok  -   10s
      Rs: Reconcile state
      Ri: Reconcile information
      7 resources
      Succeeded
    updatedAt: "2021-03-30T19:26:34Z"
  observedGeneration: 3
  template:
    exitCode: 0
    updatedAt: "2021-03-30T19:26:34Z"

What we’re looking for in this output is that all of the resources are deployed and healthy and that the reconciliation state is Succeeded.

There will be a single pod running in the tanzu-system-service-discovery namespace.

kubectl -n tanzu-system-service-discovery get po

NAME                            READY   STATUS    RESTARTS   AGE
external-dns-5fc76fcb7b-kc8g2   1/1     Running   1          76m

You should see messages similar to the following if you check the logs for this pod:

time="2021-03-31T17:50:18Z" level=info msg="Instantiating new Kubernetes client"
time="2021-03-31T17:50:18Z" level=info msg="Using inCluster-config based on serviceaccount-token"
time="2021-03-31T17:50:18Z" level=info msg="Created Kubernetes client https://100.64.0.1:443"
time="2021-03-31T17:50:19Z" level=info msg="Created Dynamic Kubernetes client https://100.64.0.1:443"
time="2021-03-31T17:50:20Z" level=info msg="Configured RFC2136 with zone 'corp.tanzu.' and nameserver '192.168.110.10:53'"

And that’s pretty much it. We can’t see that it’s actually done anything yet since there are no httpproxy resources yet, so let’s get to creating some.

Deploy Contour

Deploying Contour is very similar to the process I noted in Working with TKG Extensions and Shared Services in TKG 1.2.

The first thing we need to do is create the namespace and roles.

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/ingress/contour/namespace-role.yaml

namespace/tanzu-system-ingress created
serviceaccount/contour-extension-sa created
role.rbac.authorization.k8s.io/contour-extension-role created
rolebinding.rbac.authorization.k8s.io/contour-extension-rolebinding created
clusterrole.rbac.authorization.k8s.io/contour-extension-cluster-role created
clusterrolebinding.rbac.authorization.k8s.io/contour-extension-cluster-rolebinding created

A welcome addition in 1.3 is a pre-configured data-values file for use with a load balancer. Previously, you had to add the following to get this to work:

  service:
    type: LoadBalancer
cp tkg-extensions-v1.3.0+vmware.1/extensions/ingress/contour/vsphere/contour-data-values-lb.yaml.example contour-data-values-lb.yaml

Since we don’t need to make any changes, you can just create the necessary secret from this file.

kubectl create secret generic contour-data-values --from-file=values.yaml=contour-data-values-lb.yaml -n tanzu-system-ingress

secret/contour-data-values created

And then the extension itself can be created.

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/ingress/contour/contour-extension.yaml

extension.clusters.tmc.cloud.vmware.com/contour created

Since we requested a servioce of type LoadBalancer, NSX ALB should provision that for us.

kubectl -n tanzu-system-ingress get svc

NAME      TYPE           CLUSTER-IP       EXTERNAL-IP     PORT(S)                      AGE
contour   ClusterIP      100.64.75.181                    8001/TCP                     2h
envoy     LoadBalancer   100.65.219.204   192.168.220.2   80:30849/TCP,443:32450/TCP   2h

Very shortly after creating the Contour extension, you should see your NSX ALB SEs get created (unless they already existed) as a service of type LoadBalancer is being created and SEs are needed to process this traffic. If you check out the status of this Virtual Service in the NSX ALB UI, you’ll see that it’s all red.

This is okay though since there is really nothing listening at the other end of this service yet. We have to have an httpproxy deployed before there will be anything actually listening.

Deploy Harbor

As with the other extensions, create the namespace and roles first.

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/registry/harbor/namespace-role.yaml

namespace/tanzu-system-registry created
serviceaccount/harbor-extension-sa created
role.rbac.authorization.k8s.io/harbor-extension-role created
rolebinding.rbac.authorization.k8s.io/harbor-extension-rolebinding created
clusterrole.rbac.authorization.k8s.io/harbor-extension-cluster-role created
clusterrolebinding.rbac.authorization.k8s.io/harbor-extension-cluster-rolebinding created

And make a copy of the data-values file.

cp tkg-extensions-v1.3.0+vmware.1/extensions/registry/harbor/harbor-data-values.yaml.example harbor-data-values.yaml

You can use the same generate-passwords.sh script noted in my post Working with TKG Extensions and Shared Services in TKG 1.2 to autopopulate the passwords in this file and then manually update the harborAdminPassword value as well as the hostname value. The hostname value is the key piece for external-dns as it has to be in the DNS zone that it’s monitoring. In this example, the hostname is harbor.corp.tanzu which is in the corp.tanzu DNS zone, so it should be good to go.

I’m making one additional change from what I did in the past and using my own wildcard certificate that is already trusted through my environment. With this in place, the relevant portion of the file looks like the following:

hostname: harbor.corp.tanzu
# The network port of the Envoy service in Contour or other Ingress Controller.
port:
  https: 443
# [Optional] The certificate for the ingress if you want to use your own TLS certificate.
# We will issue the certificate by cert-manager when it's empty.
tlsCertificate:
  # [Required] the certificate
  tls.crt: |
    -----BEGIN CERTIFICATE-----
    MIIHiDCCBXCgAwIBAgITHQAAAAkDm8eswM8dBgAAAAAACTANBgkqhkiG9w0BAQsF
    ADBIMRUwEwYKCZImiZPyLGQBGRYFdGFuenUxFDASBgoJkiaJk/IsZAEZFgRjb3Jw
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    5EFc+Q0KzSIV5CLfejwVJs40QdupWffXHOYqm49zT8ejffEExUBxXH/b4rooumkc
    hpsrx5hbo/XJvS7ZbXCH/k8kDq8+9o4QEVjqYyVwA/F3+/Mv2ywGLwKY5B+WvJQt
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    R22CcKK+kduUjv0X
    -----END CERTIFICATE-----
  tls.key: |
    -----BEGIN PRIVATE KEY-----
    MIIJRAIBADANBgkqhkiG9w0BAQEFAASCCS4wggkqAgEAAoICAQC+dziVQ/U1LUaS
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    -----END PRIVATE KEY-----
  # [Optional] the certificate of CA, this enables the download
  # link on portal to download the certificate of CA
  ca.crt: |
    -----BEGIN CERTIFICATE-----
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    -----END CERTIFICATE-----
# Use contour http proxy instead of the ingress when it's true
enableContourHttpProxy: true

# [Required] The initial password of Harbor admin.
harborAdminPassword: VMware1!

And now we can create the needed secret from this file

kubectl create secret generic harbor-data-values --from-file=values.yaml=harbor-data-values.yaml  -n tanzu-system-registry

secret/harbor-data-values created

And finally we can deploy the Harbor extension.

kubectl apply -f tkg-extensions-v1.3.0+vmware.1/extensions/registry/harbor/harbor-extension.yaml

extension.clusters.tmc.cloud.vmware.com/harbor created

With Harbor deployed, we should now see an httpproxy resource in the tanzu-system-registry namespace.


kubectl -n tanzu-system-registry get httpproxy

NAME                      FQDN                       TLS SECRET   STATUS   STATUS DESCRIPTION
harbor-httpproxy          harbor.corp.tanzu          harbor-tls   valid    Valid HTTPProxy
harbor-httpproxy-notary   notary.harbor.corp.tanzu   harbor-tls   valid    Valid HTTPProxy

If we check out the logs for the external-dns pod, we’ll see that it has created the harbor.corp.tanzu and notary.harbor.corp.tanzu records.

kubectl -n tanzu-system-service-discovery logs external-dns-59d47f9588-whvnp

time="2021-03-30T22:54:43Z" level=info msg="Adding RR: harbor.corp.tanzu 0 A 192.168.220.2"
time="2021-03-30T22:54:43Z" level=info msg="Adding RR: notary.harbor.corp.tanzu 0 A 192.168.220.2"
time="2021-03-30T22:54:43Z" level=info msg="Adding RR: harbor.corp.tanzu 0 TXT \"heritage=external-dns,external-dns/owner=k8s,external-dns/resource=HTTPProxy/tanzu-system-registry/harbor-httpproxy\""
time="2021-03-30T22:54:43Z" level=info msg="Adding RR: notary.harbor.corp.tanzu 0 TXT \"heritage=external-dns,external-dns/owner=k8s,external-dns/resource=HTTPProxy/tanzu-system-registry/harbor-httpproxy-notary\""

And back in the DNS application, we can see that the new records were successfully created.

As you would expect, harbor.corp.tanzu now resolves to 192.168.220.2, the IP address assigned by NSX ALB, to Contour.

dig harbor.corp.tanzu

; <<>> DiG 9.16.6-Ubuntu <<>> harbor.corp.tanzu
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35418
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;harbor.corp.tanzu.             IN      A

;; ANSWER SECTION:
harbor.corp.tanzu.      0       IN      A       192.168.220.2

;; Query time: 0 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Wed Mar 31 12:54:00 MDT 2021
;; MSG SIZE  rcvd: 62

Harbor is accessible via it’s FQDN and no certificate warning is thrown.

Since there is now something listening at the other end of our Virtual Service, the status is no longer red in the NSX ALB UI.

What I wanted to do

While this is great, and certainly saves you the time of having to manually create DNS records, I was hoping to be able to pull this off with secure dynamic updates. There are instructions for this but it turns out that the methods have not been implemented yet (based on a recent issue). I was able to put together how this would look once the feature is available in external DNS.

A configmap is needed that provides the configuration information which external-dns will use to establish communication securely with Microsoft DNS. The only thing in this that is customized is the DNS zone name (corp.tanzu) and the AD/DNS server names (both are controlcenter.corp.tanzu).

apiVersion: v1
kind: ConfigMap
metadata:
  name: krb5.conf
data:
  krb5.conf: |
    [logging]
    default = FILE:/var/log/krb5libs.log
    kdc = FILE:/var/log/krb5kdc.log
    admin_server = FILE:/var/log/kadmind.log

    [libdefaults]
    dns_lookup_realm = false
    ticket_lifetime = 24h
    renew_lifetime = 7d
    forwardable = true
    rdns = false
    pkinit_anchors = /etc/pki/tls/certs/ca-bundle.crt
    default_ccache_name = KEYRING:persistent:%{uid}

    default_realm = CORP.TANZU

    [realms]
    CORP.TANZU = {
      kdc = controlcenter.corp.tanzu
      admin_server = controlcenter.corp.tanzu
    }

    [domain_realm]
    corp.tanzu = CORP.TANZU
    .corp.tanzu = CORP.TANZU

The data-values file will look a little bit different. I’ve removed the rfc2136-insecure flag and added rfc2136-gss-tsig (telling it to use the authentication mechanism that works with Microsoft DNS), rfc2136-kerberos-realm (DNS zone), rfc2136-kerberos-username (administrative user for the DNS zone) and rfc2136-kerberos-password (password for the administrative user). You’ll also notice that volumeMounts and volumes sections are present so that the external-dns pod can make use of the previously created configmap.

#@data/values
#@overlay/match-child-defaults missing_ok=True
---
externalDns:
  image:
    repository: projects.registry.vmware.com/tkg
  deployment:
    #@overlay/replace
    args:
    - --txt-owner-id=k8s
    - --provider=rfc2136
    - --rfc2136-host=controlcenter.corp.tanzu
    - --rfc2136-port=53
    - --rfc2136-zone=corp.tanzu
    - --rfc2136-gss-tsig
    - --rfc2136-kerberos-realm=corp.tanzu
    - --rfc2136-kerberos-username=administrator
    - --rfc2136-kerberos-password=VMware1!
    - --rfc2136-tsig-axfr
    - --source=service
    - --source=contour-httpproxy
    - --domain-filter=corp.tanzu
    volumeMounts:
    #@overlay/append
    - mountPath: /etc/krb5.conf
      name: kerberos-config-volume
      subPath: krb5.conf
    volumes:
    #@overlay/append
    - configMap:
        defaultMode: 420
        name: krb5.conf
      name: kerberos-config-volume

Hopefully we’ll see external-dns updated in the future so that this functionality can be used.

UPDATE: This is now working in TKG 1.4 as it’s using the 0.8.0 version of external-dns. you can read about the External DNS section of my newer post, Upgrading from TKG 1.3 to 1.4 (including extensions) on vSphere.

1 thought on “How to configure external-dns with Microsoft DNS in TKG 1.3 (plus Harbor and Contour)”

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