install-dotnet.ps1 fails behind authenticated proxy: credentials not applied from ProxyAddress

[aparnajyothi-y]

The install-dotnet.ps1 script fails behind authenticated proxy because it does not apply proxy credentials, even when they are provided via the ProxyAddress parameter.

The script constructs its own HttpClientHandler and WebProxy object. It does not extract credentials from the proxy URL or use those set in environment variables. As a result, it sends unauthenticated requests to the proxy, resulting in 407 Proxy Authentication Required errors. Failure logs show that the ProxyAddress with credentials is passed correctly, but the script still receives a 407. Web proxy logs confirm the request reaches the proxy without credentials, indicating that authentication details are not being applied.
Please find error screenshot for reference.

Environment Context
The runners are in a restricted network without direct internet access, so all outbound traffic must go through an authenticated proxy.

[JanProvaznik]

Thanks for the report, this feature would make sense. But, it's a new feature and install-scripts are in maintenance mode. So for now it's under the cut line for investment from our side.

[aparnajyothi-y]

Hi @JanProvaznik, Just following up to check if there are any updates or plans regarding the implementation of proxy credential support in install-dotnet.ps1 (#595). We understand from the previous comments that this would be a new feature and that install-scripts is currently in maintenance mode, but we wanted to confirm if there have been any further discussions or prioritization changes since then.

Please let us know if this feature is still being considered for future investment, or if there are any alternative recommendations you would suggest for environments requiring authenticated proxy support.

Thanks again for your support!

[JanProvaznik]

We're leaving this open to see if multiple customers need this change, then we'd prioritize working on it. Right now, no plans for implementing it.
As for resolving your problem, I realize this is quite tricky. I'd suggest making a custom copy of the install script with the functionality instead of using setup-dotnet. If you figure out how to test it you can contribute back to this repo and we'll consider merging for everyone to use.