When you attempt to deploy an ASP.NET Core project to App Service on Linux, you may run into an error during the build process – Object reference not set to an instance of an object. When you try to deploy the project to App Service on Windows, everything works, so where is the issue?
I am sure you have heard of App Service’s feature called Local Cache, which allows to cache all the files locally on the instance instead of pulling them from the shared storage which can lower the application’s load times – especially when using just-in-time compiled code like PHP. This great feature however, is only available currently on App Service on Windows, and in this article, we are going to explore the options of having something similar on App Service on Linux powered by Docker.
During Build 2017, Microsoft announced bunch of new features for App Service on Linux. One of those features announced was support for SSH support directly into the web worker instance. Based on my previous article about building a custom image for ASL, I have updated the HHVM image both on GitHub and Docker hub to have SSH support as well.
If you have been watching Connect(); or if you read the Azure blog, you should be aware by now, that Azure has recently introduced a pretty cool service called App Service on Linux. It is probably also not going to be a surprise to you if I tell you that it is being powered by Docker. And that is not the only great thing about it – you can also bring your own Docker image into App Service on Linux!