Configuring a custom domain name for a Windows Azure cloud service or storage account

When you create an application in Windows Azure, Windows Azure provides a friendly subdomain on the cloudapp.net domain so your users can access your application on a URL like http://<myapp>.cloudapp.net. Similarly, when you create a storage account, Windows Azure provides a friendly subdomain on the core.windows.net domain so your users can access your data on a URL like https://<mystorageaccount>.blob.core.windows.net. However, you can also expose your application and data on your own domain name, such as contoso.com.

This task will show you how to:

• Expose Your Application on a Custom Domain
• Expose Your Data on a Custom Domain

Expose your application on a custom domain

There are two ways you can configure the Domain Name Server (DNS) settings on your domain registrar to point to your Windows Azure hosted service:

1. CNAME or Alias record (preferred)

   With a CNAME, you map a specific domain, such as www.contoso.com or myblog.contoso.com, to the <myapp>.cloudapp.net domain name of your Windows Azure hosted application. The lifetime of the <myapp>.cloudapp.net domain name required to implement this solution is the lifetime of your hosted service and persists even if your hosted service does not contain any deployments.

   Note, however, that most domain registrars only allow you to map subdomains, such as www.contoso.com and not root names, such as contoco.com or wildcard names, such as *.contoso.com.

2. A record

   With an A record, you map a domain (e.g., contoso.com or www.contoso.com) or a wildcard domain (e.g., *.contoso.com) to the single public IP address of a deployment within a Windows Azure hosted service. Accordingly, the lifetime of this IP address is the lifetime of a deployment within your hosted service. The IP address gets created the first time you deploy to an empty slot (either production or staging) in the hosted service and is retained by the slot until you delete the deployment from that slot. You can discover this IP address from within the Windows Azure Management Portal.

   The main benefit of this approach over using CNAMEs is that you can map root domains (e.g., contoso.com) and wildcard domains (e.g., *.contoso.com), in addition to subdomains (e.g., www.contoso.com).

   Note, however, because the lifetime of the IP address is associated with a deployment, it is important not to delete your deployment if you need the IP address to persist. Conveniently, the IP address of a given deployment slot (production or staging) is persisted when using the two upgrade mechanisms in Windows Azure: VIP swaps and in-place upgrades.

The remainder of this section focuses on the CNAME approach.

Adding a CNAME record for your custom domain

To configure a custom domain name, you must create a new CNAME record in your custom domain name's DNS table. Each registrar has a similar but slightly different method of specifying a CNAME record, but the concept is the same.

1. Log on to your DNS registrar's web site, and go to the page for managing DNS. You might find this in a section, such as Domain Name, DNS, or Name Server Management.

2. Now find the section for managing CNAME's. You may have to go to an advanced settings page and look for the words CNAME, Alias, or Subdomains.

3. Finally, you must provide a subdomain alias, such as www. Then, you must provide a host name, which is your application's cloudapp.net domain in this case. For example, the following CNAME record forwards all traffic from www.contoso.com to contoso.cloudapp.net, the DNS name of our deployed application:

Alias	Host name
www	contoso.cloudapp.net

A visitor of www.contoso.com will never see the true host (contoso.cloudapp.net), so the forwarding process is invisible to the end user.

Expose your data on a custom domain

This section describes how to associate your own custom domain with a Windows Azure storage account. When you complete the tasks in this section, your users (assuming they have sufficient access rights) will be able to access blobs within this storage account as follows:

Resource Type	URL Formats
Storage account	Default format: http://<mystorageaccount>.blob.core.windows.net Custom domain format: http://<custom.sub.domain>
Blob	Default format: http://<mystorageaccount>.blob.core.windows.net/<mycontainer>/<myblob> Custom domain format: http://<custom.sub.domain>/<mycontainer>/<myblob>
Root container	Default format: http://<mystorageaccount>.blob.core.windows.net/<myblob> or http://<mystorageaccount>.blob.core.windows.net/$root/<myblob> Custom domain format: http://<custom.sub.domain>/<myblob> or http://<custom.sub.domain>/$root/<myblob>

 

Task Overview

Configuring a custom domain for a Windows Azure storage account involves several tasks, some of which you will perform in the Windows Azure Management Portal and others in your domain registrar's portal.

Task	Portal
1. Configure a custom domain for the storage account	Windows Azure
2. Create a CNAME record to use for domain validation in Windows Azure	Domain Registrar
3. Validate the subdomain in Windows Azure	Windows Azure
4. Create a CNAME record that associates the subdomain with the storage account	Domain Registrar
5. Verify the subdomain references the Blob service	Web Browser

 

Configure a custom domain for the storage account

1. Log on to the Windows Azure Management Portal.

2. In the Web Sites tab, click the name of your storage account.

3. Click the Configure tab.

4. At the bottom of the screen click Manage Domains.

5. On the Manage Custom Domain dialog, in the Domain name field, enter your domain name.

6. Click register.

   The CName record text box populates with the URL you need to use to validate the domain.

7. Copy the URL and paste into an email or a text editor for later use.

   You must now register the CNAME record above with your provider that points URI provided to verify.azure.com. Clicking the validate button before you have configure the CNAME record with your registrar will return the message "There is no DNS record for '<URL>' that points to 'verify.azure.com'. Create a record with your DNS provider and try again. DNS records can take some time to propagate. If you think you have already configured this properly then try again in a few minutes."

 

Create a CNAME record to use for domain validation in Windows Azure

1. On your domain registrar's web site, add a CNAME record to the domain, using the alias and destination host name that you copied from the Validate Custom Domain dialog box.

   For example, if you are using the subdomain data.contoso.com, your CNAME record will use values that look similar to this:

   • Alias name: 0e6cd138-82b8-4136-adae-91dbaa369576.data.contoso.com
   • Points to host name: verify.azure.com
   Note

   Different domain registrars use different names for the two parameters in the CNAME record.

2. Allow time for the CNAME record to propagate to all name servers on the Internet. Propagation can take 12 hours or longer.

 

Validate the subdomain in Windows Azure

1. In the Web Sites tab, click the name of your storage account.

2. Click the Configure tab.

3. At the bottom of the screen click Manage Domains.

4. On the Manage Custom Domain click validate.

   If the validation is successful, you will get the message Your custom domain is active.

   Note

   If the validation is not successful you will receive the message "There is no DNS record for '<URL>' that points to 'verify.azure.com'. Create a record with your DNS provider and try again. DNS records can take some time to propagate. If you think you have already configured this properly then try again in a few minutes."

   Important

   Windows Azure only validates that a CNAME record for the domain corresponds to the alias that you copied from the Validate Custom Domain dialog box. (In the Properties pane for the custom domain, this alias is displayed under CName redirect.) Windows Azure does not check to make sure that you used a subdomain for the custom domain. If you did not use a subdomain for the custom domain, you will not be able to access your blobs using the custom domain name, even if validation succeeds.

 

Create a CNAME record to associate the subdomain with the storage account

1. On the domain registrar's web site, add a second CNAME record to the domain. This CNAME record associates the validated custom subdomain name with the Windows Azure storage account.

   For example, if your validated subdomain is data.contoso.com, create a CNAME record with the following entries:

   • Alias name: data.contoso.com
   • Points to host name: <mystorageaccount>.blob.core.windows.net

2. Allow time for the CNAME record to propagate to all name servers on the Internet.

After propagation of the CNAME record completes, you should be able to use the subdomain in URIs to reference public containers and blobs in the storage account.

 

Verify that the subdomain references the blob service

In a web browser, use a URI in the following format to access a blob in a public container:

• http://<custom.sub.domain>/<mycontainer>/<myblob>

For example, you might type the following URI to access a web form via a data.contoso.com custom subdomain that maps to a blob in your myforms container:

• http://data.contoso.com/myforms/applicationform.htm

Additional Resources

• How to Map CDN Content to a Custom Domain