azure-dns-docker

This application will discover your current public IP address and then update an A-record of your choice within an Azure DNS Zone.

Preparing the Azure DNS Zone and Service Principal (one-time setup)

Ensure that you've created the DNS Zone for the domain in question

Create a DNS Zone using the Azure Portal following these instructions.

Create a service principal in Azure Active Directory and create a secret

1. Inside the Azure Portal, find your Azure Active Directory page in the left-hand menu.
2. Choose App Registrations from the left-hand menu for your Azure Active Directory.
3. Click the New Registration button.
4. Provide a name - e.g. AzureDnsDocker - and leave all other values as their defaults.
5. Click Register.
6. Copy the Application (Client) ID value; you'll need this for the CLIENTID environment variable.
7. Copy the Directory (Tenant) ID value; you'll need this for the TENANTID environment variable.
8. Click the Certificates & secrets option in your app's left-hand menu.
9. Click the New Client Secret button.
10. Give the secret a name - e.g. AzureDnsDocker - and choose an expiration period you're comfortable with.
11. Copy the new secret value; you'll need this for the SECRET environment variable.
12. Go back to the main Azure left-hand menu (top left) and click Home.
13. Under the Navigate heading, choose Subscriptions.
14. Find the subscription associated with the DNS Zone and copy the Subscription ID; you'll need this for the SUBSCRIPTIONID environment variable.

Grant the service principal read and write access to your DNS Zone

1. Go to your DNS Zone within the Azure Portal.
2. In the zone's left-hand menu, choose Access control (IAM).
3. Click the Add button and choose Add role assignment.
4. Choose the DNS Zone Contributor role.
5. In the Select box, start typing the name you chose for your app in the previous section, select the item in the results, and then click Save.

Example Usage

docker run -d --name azure-dns-docker \
-e TENANTID={tenant-id-guid} \
-e CLIENTID={client-id-guid} \
-e SECRET={secret} \
-e SUBSCRIPTIONID={subscription-id-guid} \
-e RESOURCEGROUP={resource-group-name} \
-e ZONENAME={domain-name}
-e RECORDNAME={host-name}
cpwood/azure-dns-docker

For example, to set the A-record for foo.bar.com in the bar.com DNS Zone within a Resource Group Bar, you'd do this:

docker run -d --name azure-dns-docker \
-e TENANTID=004097ec-5f22-400d-87ef-9c5a75c8a95c \
-e CLIENTID=03022824-f618-430e-8e73-18cef20d35ab \
-e SECRET=oaaodgioadgadoigjda_g8sg7 \
-e SUBSCRIPTIONID=0a32c718-edf0-443c-bba3-37578e0346c6 \
-e RESOURCEGROUP=Bar \
-e ZONENAME=bar.com
-e RECORDNAME=foo
cpwood/azure-dns-docker

You can also specify the following two optional environment variables:

• TTL - the Time-To-Live value for the created A-record (default value is 300 - 300 seconds, i.e. 5 minutes); and
• DELAY - the delay between each attempt to check the public IP address and update the DNS Zone (default value is 90000 - 90,000 milliseconds, i.e. 15 minutes).

Can I update more than one A-record?

No, however you could manually create CNAME records within your DNS Zone pointing to the A-record updated by this application.