Docker Settings For ASP.net Core On Azure Linux App Service

With Azure App Service currently being 50% off for Linux, people are taking advantage and halving their .NET core hosting bill. And why wouldn’t you!? Because Azure App Service is fully PaaS, the underlying OS doesn’t make too much of a difference both from a deployment and management perspective.

Most deployment guides floating around the web center on deploying to a Windows App Service, which really isn’t too different to the Linux version, except for one important step. If you have deployed your ASP.net Core code and are not seeing anything when you visit your website in a browser, read on.

Docker Startup File

Linux App Service actually runs Docker under the hood. To get everything starting correctly you actually need to set a “startup file”. This is essentially the entry point for your app.

Inside the Azure Portal, inside your App Service, under the Settings category, find the option for “Docker Container”. Here is where you can set the runtime stack, but more importantly, your startup details.

For a dotnet project, the startup file line should read :  dotnet /home/site/wwwroot/{yourdllhere}

Where yourdllhere is the DLL of your main web project in your deployment. In practice it should end up looking a bit like this :

Once saved, you should head back to the app service dashboard and restart your service. It does take a while to boot up first time, so wait 5 minutes and give it a spin!

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