SpaTemplate angular - Publish to Azure - Error: Cannot find module 'aspnet-webpack' - asp.net-core

Question

I use the asp.net core angular spatemplate. The project is running without problems on my local machine. However, when I publish it to azure I run into an internal server error.
After setting the aspnetcore_environment to development in the azure portal, I can see a the error:
Exception: Call to Node module failed with error: Webpack dev middleware failed because of an error while loading 'aspnet-webpack'. Error was: Error: Cannot find module 'aspnet-webpack'
I found some hints here https://github.com/sgbj/generator-aspnetcore-angular2/issues/23
Basically it says the node_modules folder is missing in the production environment. And it describes a way to add it manually to the project.json file. But the spatemplate didn't create such a file... it contains a classic *.proj
I am very new to web development and I don't know how to add the missing dependency to the proj file. And I am not sure if this is really the issue, because the sample I am following on the web https://channel9.msdn.com/events/Visual-Studio/Visual-Studio-2017-Launch/WEB-103 is not setting anything in this direction.
If I create a plain new project with
dotnet new angular
and I publish it everything works fine without any issues?! So I have the feeling I destroyed something in the solution?! Any idea?
My question is how can I set the node_modules for publishing?

Answer 1

In Startup.cs you probably have the below in Configure() method:
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions {
HotModuleReplacement = true
});
}
This enables hot module replacement with webpack. When you make a change and save a file, webpack automatically re compiles the angular app so your browser picks up the changes without you reloading the page. You don't want this functionality when publishing.
"env.IsDevelopment()" will check for an environment variable on your PC = ASPNETCORE_ENVIRONMENT=Development
In the app service, add an app setting like below:
Alternatively you could comment the hot module replacement out.

Answer 2

Finally I found a solution for this problem. I removed the Publish Profile in my VS2017 solution and to delete the related app service on Azure. After creating everything new again the publishing works well again. I hope this will never ever happen in production.