Pretzel and Kudu on Azure

I’ve published a couple of posts about that I’m using Pretzel to generate the HTML pages of my blog. However, I didn’t talk about the hosting.

Actually, it’s quite simple: The source files for the site are hosted in a git repository on GitHub. The generated site is hosted in Azure. Whenever I push changes to the git repository, the web site will be updated automatically.

The setup is a two-stage process: first, you have to create a Azure App Service and connect it to your git repository. The steps involved are documented very well in Continuous Deployment to Azure App Service.

The second step is to execute Pretzel on the Azure side. Enter Kudu. Kudu is the engine behind git deployments in Azure. It’s well documented in the wiki at GitHub. By default, Kudu will locate the relevant csproj file, compile it, and copy the artifacts to wwwroot. That’s why many web sizes running on Azure contain an empty “shim project”.

However, you can simplify the setup by customizing Kudu’s behavior. In my case I want Kudu to run pretzel.exe to generate the static HTML files from my sources:

1. Add pretzel.exe (and all its dependencies) to your git repository (I’ve used a subfolder named _pretzel)

2. Add a batch file deploy.cmd to execute pretzel.exe:

   @echo off
   echo Running Pretzel...
   _pretzel\pretzel.exe bake --destination=%DEPLOYMENT_TARGET%
   

   bake is the Pretzel’s command to generate the files, and the destination folder is %DEPLOYMENT_TARGET%, which is the wwwroot folder.

3. Instruct Kudu to execute that deploy.cmd by creating a file .deployment with following content:

   [config]
   command = deploy.cmd
   

That’s all. Whenever I push changes to the git repository, Kudu will get the current files, execute Pretzel, and the updated web site is public. The whole process takes less than a minute.

Of course this can be adapted to any other static site generator too, e.g. Jekyll.