Static site hosting on Azure Storage with a custom domain and TLS

A while ago, I blogged about webhookd. It is an application, written in Go, that can easily convert a folder structure with shell scripts into webhooks. With the help of CertMagic, I modified the application to support Let’s Encrypt certificates. The application is hosted on an Azure Linux VM that uses a managed identity to easily allow scripts that use the Azure CLI to access my Azure subscription.

I also wrote a very simple Vue.js front-end application that can call these webhooks. It’s just an index.html, a 404.html and some CSS. The web page uses Azure AD authentication to an intermediary Azure Function that acts as some sort of proxy to the webhookd server.

Since a few weeks, Azure supports hosting static sites in an Azure Storage Account. Let’s take a look at how simple it is to host your files there and attach a custom DNS name and certificate via Azure CDN.

Enable static content on Storage Account

In your Azure Storage General Purpose v2 account, simply navigate to Static website, enable the feature and type the name of your index and error document:

When you click Save, the endpoint is shown. You will also notice the $web link to the identically named container. You will need to upload your files to that container using the portal, Storage Explorer or even the Azure CLI. With the Azure CLI, you can use this command:

az storage blob upload \
--container-name mystoragecontainer \
--name blobName \
--file ~/path/to/local/file

Custom domain and certificate

It’s great that I can access my site right away, but I want to use https://azdeploy.baeke.info instead of that name. To do that, create a CDN endpoint. In the storage account settings, find the Azure CDN option and create a new CDN profile and endpoint.

Important: in the settings, set the origin hostname to the primary endpoint you were given when you enabled the static website on the storage account

When the profile and endpoint is created, you can open it in the Azure Portal:

In your case, the custom domains list will still be empty at this point. You will have an new endpoint hostname (ending in azureedge.net) that gets its content from the origin hostname. You can browse to the endpoint hostname now as well.

Although the endpoint hostname is a bit better, I want to browse to this website with a custom domain name. Before we enable that, create a CNAME record in your DNS zone that maps to the endpoint hostname. In my case, in my CloudFlare DNS settings, I added a CNAME that maps azdeploy.baeke.info to gebastatic.azureedge.net. When that is finished, click + Custom Domain to add, well, your custom domain.

The only thing left to do is to add a certificate for your custom domain. Although you can add your own certificate, Azure CDN can also provide a certificate and completely automate the certificate management. Just make sure that your created the CNAME correctly and you should be good to go:

Custom certificate via Azure CDN

Above, I enabled the custom domain HTTPS feature and chose CDN Managed. Although it took a while for the certificate to be issued and copied to all points of presence (POPs), the process was flawless. The certificate is issued by Digicert:

Azure CDN certificate issued by Digicert

Some loose ends?

Great! I can now browse to https://azdeploy.baeke.info securely. Sadly, when you choose the Standard Microsoft CDN tier as the content delivery network, http to https redirection is not supported. The error when you browse to the http endpoint is definitely not pretty:

Users will probably think there is an error of some sorts. If you switch the CDN to Verizon Premium, you can create a redirection rule with the rules engine:

Premium Verizon Redirect Rule

When you add the above rule to the rules engine, it takes a few hours before it becomes active. Having to wait that long feels awkward in the age of instant gratification!

Conclusion

Being able to host your static website in Azure Storage greatly simplifies hosting both simple static websites as more advanced single page applications or SPAs. The CDN feature, including its automatic certificate management feature, adds additional flexibility.

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