Use YARP to intercept all outbound requests of an app for testing purposes

[weitzhandler]

Hi,

I created an Aspire web app with its API project calling external resources (e.g. www.github.com).
I use DistributedApplicationTestingBuilder and I want to take control of the app and intercept all outbound requests that are not made within the app-host umbrella (e.g. localhost).
I don't want to use HttpHandler proxies I prefer to leave the app code untouched and rather perform it all in the testing projects.

Can I achieve this with YARP? Any other alternatives otherwise?

Thanks

[MihaZupan]

No, YARP is an L7 HTTP proxy.
If you want to hijack outgoing traffic for your process, this isn't something YARP can do for you out of the box.

What are you trying to do with the intercepted requests?

You'd have to intercept connections yourself (e.g. setting a proxy, redirecting the connection with the help of the OS, MITM software, etc.).
The easiest option is likely to set environment variable that instruct your applications to use a forward HTTP proxy, and point those requests at your server.

And even if you do, you'd have to deal with how to process proxy requests or how to present the correct certs yourself.
While technically possible (you can look at https://github.com/MihaZupan/Mitm.Net for inspiration), it's all custom.

[weitzhandler]

My goal is to replace all remote calls of all integration/acceptance tests and reply with fake data.