In our Infrastructure as code live stream series, Marcel Zehner and I covered a new feature in the Azure IAC space. Namely deployment scripts. With deployment scripts for Azure, you can run PowerShell or Bash (CLI) scripts within your ARM templates.
You may have heard of Custom script extension for Azure Windows VMs, this is sort of the same thing. Making you able to call external systems during deployment, or perform the last-mile configuration to your infrastructure.