Azure DNS

Configuration for Azure DNS.

  • Code: azuredns
  • Since: v4.13.0

Here is an example bash command using the Azure DNS provider:

### Using client secret

AZURE_CLIENT_ID=<your service principal client ID> \
AZURE_TENANT_ID=<your service principal tenant ID> \
AZURE_CLIENT_SECRET=<your service principal client secret> \
lego --domains example.com --email your_example@email.com --dns azuredns run

### Using client certificate

AZURE_CLIENT_ID=<your service principal client ID> \
AZURE_TENANT_ID=<your service principal tenant ID> \
AZURE_CLIENT_CERTIFICATE_PATH=<your service principal certificate path> \
lego --domains example.com --email your_example@email.com --dns azuredns run

### Using Azure CLI

az login \
lego --domains example.com --email your_example@email.com --dns azuredns run

### Using Managed Identity (Azure VM)

AZURE_TENANT_ID=<your service principal tenant ID> \
AZURE_SUBSCRIPTION_ID=<your target zone subscription ID> \
AZURE_RESOURCE_GROUP=<your target zone resource group name> \
lego --domains example.com --email your_example@email.com --dns azuredns run

### Using Managed Identity (Azure Arc)

AZURE_TENANT_ID=<your service principal tenant ID> \
AZURE_SUBSCRIPTION_ID=<your target zone subscription ID> \
AZURE_RESOURCE_GROUP=<your target zone resource group name> \
IMDS_ENDPOINT=http://localhost:40342 \
IDENTITY_ENDPOINT=http://localhost:40342/metadata/identity/oauth2/token \
lego --domains example.com --email your_example@email.com --dns azuredns run

Credentials

Environment Variable Name Description
AZURE_CLIENT_CERTIFICATE_PATH Client certificate path
AZURE_CLIENT_ID Client ID
AZURE_CLIENT_SECRET Client secret
AZURE_RESOURCE_GROUP DNS zone resource group
AZURE_SUBSCRIPTION_ID DNS zone subscription ID
AZURE_TENANT_ID Tenant ID

The environment variable names can be suffixed by _FILE to reference a file instead of a value. More information here.

Additional Configuration

Environment Variable Name Description
AZURE_AUTH_METHOD Specify which authentication method to use
AZURE_AUTH_MSI_TIMEOUT Managed Identity timeout duration
AZURE_ENVIRONMENT Azure environment, one of: public, usgovernment, and china
AZURE_POLLING_INTERVAL Time between DNS propagation check
AZURE_PRIVATE_ZONE Set to true to use Azure Private DNS Zones and not public
AZURE_PROPAGATION_TIMEOUT Maximum waiting time for DNS propagation
AZURE_TTL The TTL of the TXT record used for the DNS challenge
AZURE_ZONE_NAME Zone name to use inside Azure DNS service to add the TXT record in

The environment variable names can be suffixed by _FILE to reference a file instead of a value. More information here.

Description

Several authentication methods can be used to authenticate against Azure DNS API.

Default Azure Credentials (default option)

Default Azure Credentials automatically detects in the following locations and prioritized in the following order:

  1. Environment variables for client secret: AZURE_CLIENT_ID, AZURE_TENANT_ID, AZURE_CLIENT_SECRET
  2. Environment variables for client certificate: AZURE_CLIENT_ID, AZURE_TENANT_ID, AZURE_CLIENT_CERTIFICATE_PATH
  3. Workload identity for resources hosted in Azure environment (see below)
  4. Shared credentials (defaults to ~/.azure folder), used by Azure CLI

Link:

Environment variables

Client secret

The Azure Credentials can be configured using the following environment variables:

  • AZURE_CLIENT_ID = “Client ID”
  • AZURE_CLIENT_SECRET = “Client secret”
  • AZURE_TENANT_ID = “Tenant ID”

This authentication method can be specificaly used by setting the AZURE_AUTH_METHOD environment variable to env.

Client certificate

The Azure Credentials can be configured using the following environment variables:

  • AZURE_CLIENT_ID = “Client ID”
  • AZURE_CLIENT_CERTIFICATE_PATH = “Client certificate path”
  • AZURE_TENANT_ID = “Tenant ID”

This authentication method can be specificaly used by setting the AZURE_AUTH_METHOD environment variable to env.

Workload identity

Workload identity allows workloads running Azure Kubernetes Services (AKS) clusters to authenticate as an Azure AD application identity using federated credentials.

This must be configured in kubernetes workload deployment in one hand and on the Azure AD application registration in the other hand.

Here is a summary of the steps to follow to use it :

  • create a ServiceAccount resource, add following annotations to reference the targeted Azure AD application registration : azure.workload.identity/client-id and azure.workload.identity/tenant-id.
  • on the Deployment resource you must reference the previous ServiceAccount and add the following label : azure.workload.identity/use: "true".
  • create a fedreated credentials of type Kubernetes accessing Azure resources, add the cluster issuer URL and add the namespace and name of your kubernetes service account.

Link :

This authentication method can be specificaly used by setting the AZURE_AUTH_METHOD environment variable to wli.

Azure Managed Identity

Azure Managed Identity (with Azure workload)

The Azure Managed Identity service allows linking Azure AD identities to Azure resources, without needing to manually manage client IDs and secrets.

Workloads with a Managed Identity can manage their own certificates, with permissions on specific domain names set using IAM assignments. For this to work, the Managed Identity requires the Reader role on the target DNS Zone, and the DNS Zone Contributor on the relevant _acme-challenge TXT records.

For example, to allow a Managed Identity to create a certificate for “fw01.lab.example.com”, using Azure CLI:

export AZURE_SUBSCRIPTION_ID="00000000-0000-0000-0000-000000000000"
export AZURE_RESOURCE_GROUP="rg1"
export SERVICE_PRINCIPAL_ID="00000000-0000-0000-0000-000000000000"

export AZURE_DNS_ZONE="lab.example.com"
export AZ_HOSTNAME="fw01"
export AZ_RECORD_SET="_acme-challenge.${AZ_HOSTNAME}"

az role assignment create \
--assignee "${SERVICE_PRINCIPAL_ID}" \
--role "Reader" \
--scope "/subscriptions/${AZURE_SUBSCRIPTION_ID}/resourceGroups/${AZURE_RESOURCE_GROUP}/providers/Microsoft.Network/dnszones/${AZURE_DNS_ZONE}"

az role assignment create \
--assignee "${SERVICE_PRINCIPAL_ID}" \
--role "DNS Zone Contributor" \
--scope "/subscriptions/${AZURE_SUBSCRIPTION_ID}/resourceGroups/${AZURE_RESOURCE_GROUP}/providers/Microsoft.Network/dnszones/${AZURE_DNS_ZONE}/TXT/${AZ_RECORD_SET}"

A timeout wrapper is configured for this authentication method. The duraction can be configured by setting the AZURE_AUTH_MSI_TIMEOUT. The default timeout is 2 seconds. This authentication method can be specificaly used by setting the AZURE_AUTH_METHOD environment variable to msi.

Azure Managed Identity (with Azure Arc)

The Azure Arc agent provides the ability to use a Managed Identity on resources hosted outside of Azure (such as on-prem virtual machines, or VMs in another cloud provider).

While the upstream azidentity SDK will try to automatically identify and use the Azure Arc metadata service, if you get azuredns: DefaultAzureCredential: failed to acquire a token. error messages, you may need to set the environment variables:

  • IMDS_ENDPOINT=http://localhost:40342
  • IDENTITY_ENDPOINT=http://localhost:40342/metadata/identity/oauth2/token

A timeout wrapper is configured for this authentication method. The duraction can be configured by setting the AZURE_AUTH_MSI_TIMEOUT. The default timeout is 2 seconds. This authentication method can be specificaly used by setting the AZURE_AUTH_METHOD environment variable to msi.

Azure CLI

The Azure CLI is a command-line tool provided by Microsoft to interact with Azure resources. It provides an easy way to authenticate by simply running az login command. The generated token will be cached by default in the ~/.azure folder.

This authentication method can be specificaly used by setting the AZURE_AUTH_METHOD environment variable to cli.

Open ID Connect

Open ID Connect is a mechanism that establish a trust relationship between a running environment and the Azure AD identity provider. It can be enabled by setting the AZURE_AUTH_METHOD environment variable to oidc.

More information