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Azure DNS

8 min read

Learn how to use cert-manager to set up TLS certificates using Azure DNS for DNS01 challenges.

cert-manager allows you to enable HTTPS on your Coder installation, regardless of whether you're using Let's Encrypt or you have your own certificate authority.

This guide will show you how to install cert-manager v1.4.0 and set up your cluster to issue Let's Encrypt certificates for your Coder installation so that you can enable HTTPS on your Coder deployment. It will also show you how to configure your Coder hostname and dev URLs.

There are three available methods to configuring the Azure DNS DNS01 Challenge via cert-manager:

This guide will only walk through the first option, though the prerequisites are the same regardless of which option you choose.

We recommend reviewing the official cert-manager documentation if you encounter any issues or if you want info on using a different certificate issuer.

Prerequisites

You must have:

You should also:

  • Be a cluster admin
  • Have access to your DNS provider
  • Have a paid Azure account that allows you to access Azure DNS

Step 1: Create an Azure DNS Zone

Log into the Azure Portal. Using the search bar, look for DNS Zones and navigate to this service.

If Azure DNS is the registrar for your domain, the zone will already exist so you can skip to Step 3.

Click New to create a new zone, and when prompted:

  1. Select your subscription and the resource group where your Coder deployment is

  2. Provide a name for your new zone

Click Review + create. Review the summary information, and if it's correct, click Create to proceed.

Once Azure has deployed your resource, click Go to resource. Make a note of the name server records (e.g., ns1-09.azure-dns.com.) presented to you, since you'll need to provide these four values to your domain provider.

Step 2: Assign Azure name server records to your domain

Navigate to your domain provider, and add the four Azure name server records to the domain you're using for your Coder deployment.

Step 3: Add cert-manager to your Kubernetes cluster

  1. Install cert-manager:

    kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.4.0/cert-manager.yaml
    
  2. Check that cert-manager installs correctly by running

    kubectl get CustomResourceDefinition | grep cert-manager
    

    You should see certificates, certificate requests, challenges, cluster issuers, issuers, and orders.

  3. Next, check that your services are running in the cert-manager namespace

    kubectl get all -n cert-manager
    
    NAME                                       READY   STATUS    RESTARTS   AGE
    cert-manager-7cd5cdf774-vb2pr              1/1     Running   0          84s
    cert-manager-cainjector-6546bf7765-ssxhf   1/1     Running   0          84s
    cert-manager-webhook-7f68b65458-zvzn9      1/1     Running   0          84s
    

Step 4: Set up a managed identity

AAD Pod Identities enables you to assign an Active Directory Managed Identity to a pod. This allows you to create the DNS records without having to add your credentials to the cluster.

To create the identity with access to the DNS Zone:

# Choose a unique identity name and the resource group to create identity in
IDENTITY=$(az identity create --name $IDENTITY_NAME --resource-group $IDENTITY_GROUP )

# Get principalId to use for role assignment
PRINCIPAL_ID=$(echo $IDENTITY | jq -r '.principalId')

# Identity binding
CLIENT_ID=$(echo $IDENTITY | jq -r '.clientId')
RESOURCE_ID=$(echo $IDENTITY | jq -r '.id')

# Get existing DNS Zone ID
ZONE_ID=$(az network dns zone show --name $ZONE_NAME --resource-group $ZONE_GROUP --query "id" -o tsv)

# Create role assignment
az role assignment create --role "DNS Zone Contributor" --assignee $PRINCIPAL_ID --scope $ZONE_ID

Step 5: Deploy the managed identity

  1. Export the following environment variables with your own values:

    export SUBSCRIPTION_ID="05e8b285-4ce1-46a3-b4c9-f51ba67d6acc"
    export RESOURCE_GROUP="workshop-202103"
    export CLUSTER_NAME="coder-workshop-202103"
    

    The subscription ID comes from your Azure subscription. The resource group should be set to the resource group that owns the cluster. The cluster name is the name Azure uses to refer to the required Kubernetes cluster.

  2. Deploy the AAD Pod Identity components to an RBAC-enabled cluster:

    kubectl apply -f https://raw.githubusercontent.com/Azure/ aad-pod-identity/master/deploy/infra/deployment-rbac.yaml
    
    # For AKS clusters, deploy the MIC and AKS add-on exception by running the following
    kubectl apply -f https://raw.githubusercontent.com/Azure/ aad-pod-identity/master/deploy/infra/mic-exception.yaml
    

    If you're using a non-RBAC cluster, remove the -rbac flag from the initial command

  3. Deploy AzureIdentity and AzureIdentityBinding. To do so, create an azureId.yaml file using the template below to deploy the custom resources required to assign the identity:

    apiVersion: "aadpodidentity.k8s.io/v1"
    kind: AzureIdentity
    metadata:
      annotations:
        # We recommend using namespaced identities https://azure.github.io/ aad-pod-identity/docs/configure/match_pods_in_namespace/
        aadpodidentity.k8s.io/Behavior: namespaced
      name: certman-identity
      namespace: cert-manager # Change to your preferred namespace
    spec:
      type: 0 # MSI
      resourceID: <Identity_Id> # Resource ID From Previous step
      clientID: <Client_Id> # Client ID from previous step
    ---
    apiVersion: "aadpodidentity.k8s.io/v1"
    kind: AzureIdentityBinding
    metadata:
      name: certman-id-binding
      namespace: cert-manager # Change to your preferred namespace
    spec:
      azureIdentity: certman-identity
      selector: certman-label # The label that needs to be set on cert-manager pods
    
  4. Apply the azureId.yaml file:

    kubectl apply -f azureId.yaml
    
  5. Set the pod identity label on the cert-manager pod:

    spec:
      template:
        metadata:
          labels:
            aadpodidbinding: certman-label # must match selector in AzureIdentityBinding
    

    This label tells the cluster which pods are allowed to use the IAM role specified earlier. For our purposes, we want the cert-manager pod to be able to set the DNS records for dns01 challenges. The side effect is that any pod with that label will be able to change DNS settings in the authorized zone.

Step 6: Create the ACME Issuer

  1. Create a file called letsencrypt.yaml (you can name it whatever you'd like) to specify the hostedZoneName, resourceGroupName and subscriptionID fields for the DNS Zone:

    apiVersion: cert-manager.io/v1
    kind: ClusterIssuer
    metadata:
      name: letsencrypt
    spec:
      acme:
        email: [email protected]
        server: https://acme-v02.api.letsencrypt.org/directory
        privateKeySecretRef:
          name: example-issuer-account-key
        solvers:
          - selector:
              dnsZones:
                -  # Your Azure DNS Zone
            dns01:
              azureDNS:
                subscriptionID: SUBSCRIPTION_ID
                resourceGroupName: RESOURCE_GROUP
                hostedZoneName: ZONE_ID
                # Azure Cloud Environment, default to AzurePublicCloud
                environment: AzurePublicCloud
    

    More information on the values in the YAML file above can be found in the dns01 solver configuration documentation.

  2. Apply your configuration changes:

    kubectl apply -f letsencrypt.yaml
    

    If successful, you'll see a response similar to:

    clusterissuer.cert-manager.io/letsencrypt created
    

Step 7: Install Coder

At this point, you're ready to install Coder. However, to use all of the functionality you set up in this tutorial, use the following helm install command instead:

helm install coder coder/coder --namespace coder \
  --version=<CODER_VERSION> \
  --set devurls.host="*.coder.exampleCo.com" \
  --set ingress.host="coder.exampleCo.com" \
  --set ingress.tls.enable=true \
  --set ingress.tls.devurlsHostSecretName=coder-devurls-cert \
  --set ingress.tls.hostSecretName=coder-root-cert \
  --set ingress.annotations."cert-manager\.io/cluster-issuer"="letsencrypt" \
  --wait

The hostSecretName and devurlsHostSecretName are arbitrary strings that you should set to some value that does not conflict with any other secrets in the Coder namespace.

There are also a few additional steps to make sure that your hostname and dev URLs work.

  1. Check the contents of your namespace:

    kubectl get all -n <your_namespace> -o wide
    

    Find the service/ingress-nginx line and copy its external IP value.

  2. Return to Azure and go to DNS zones.

  3. Create a new record for your hostname; provide coder as the record name, and paste the external IP as the value. Save.

  4. Create another record for your dev URLs: set it to *.dev.exampleCo or similar and use the same external IP as the previous step for value. Save.

At this point, you can return to step 6 of the installation guide to obtain the admin credentials you need to log in.

Troubleshooting

If you are not getting a valid certificate after redeploying, see cert-manager's troubleshooting guide for additional assistance.

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