Using angular template project. Running "ng serve" independently fails when trying to proxy request to dotnet.

[AdamJonsson]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

It seems that the template angular project does not work with serving independently.

If one is running npm start from ClientApp and dotnet separately, angular can not communicate with dotnet.

Angular outputs the following when trying to call weatherforecast.
[webpack-dev-server] [HPM] Error occurred while proxying request localhost:44403/weatherforecast to http://localhost:55048/ [ECONNREFUSED] (https://nodejs.org/api/errors.html#errors_common_system_errors)

If the project is started only using dotnet watch or dotnet run, the project is working as expected.

Expected Behavior

Not getting any proxy errors. Should work the same as running the project using only dotnet watch or dotnet run.

Steps To Reproduce

You can follow the official documentation for creating an angular project. Here is a summery:

• Create a new project using dotnet new angular -o my-new-app
• Run npm install in ClientApp
• Run npm start in ClientApp
• Run dotnet watch or dotnet run in project root folder.
• Go to fetch page of the example project
• Error should not occur.

Exceptions (if any)

[webpack-dev-server] [HPM] Error occurred while proxying request localhost:44403/weatherforecast to http://localhost:55048/ [ECONNREFUSED] (https://nodejs.org/api/errors.html#errors_common_system_errors)

.NET Version

7.0.100

Anything else?

.NET SDK:
Version: 7.0.100
Commit: e12b7af219

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19045
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\7.0.100\

Host:
Version: 7.0.0
Architecture: x64
Commit: d099f075e4

.NET SDKs installed:
6.0.403 [C:\Program Files\dotnet\sdk]
7.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 3.1.31 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

[javiercn]

@AdamJonsson thanks for contacting us.

When we launch the proxy, we infer the target destination by looking at the environment variables dotnet sets (ASPNETCORE_URLS and ASPNETCORE_HTTPS__PORT), but if you launch it yourself, we do not know where the .NET API is exposed.

If you want to launch the project separately, you can either use an environment variable or change the value in proxy.conf.json

[AdamJonsson]

@javiercn

Thanks for the fast response! Missed that there exist environment variable for the port and URL. Perhaps that info can be added in the official documentation when creating an angular project with dotnet?

Angular project template with Asp.net

[javiercn]

@AdamJonsson feel free to send a PR on the docs to add this if you want to contribute.

Otherwise, @Rick-Anderson or @guardrex will add a small comment on the section about launching NPM standalone.

[guardrex]

I'll take care of it.

UPDATE: The PR is up. I'll have Rick sign-off 👀, unless u want to look and approve.

dotnet/AspNetCore.Docs#27797