Linux Azure App service HttpClient host header rewrite

Question

We have 2 Linux Web apps running in Azure ( blessed images, not custom ones) running on .NET 6 with custom domains - one API and an MVC app. It's a multitenant organization and the API is using the host header from the incoming HTTP request to resolve a tenants database. So far so good - on IIS everything is working great - we are setting the host header in the HttpClientFactory with the correct domain name, sending the request and the API does its job.

Now the problem - when deployed to Azure, when we set the header to the domain from which the request should be sent(which is the domain we are currently on), the container goes in to a loop when the first HTTP request occurs, executing this request over and over again and after some time our timeout DelegateHandler on the HttpClient is being hit. If we do not set the header the loop stops but we do not have the correct Host header in the request and our API is unable to process the request.

I know there is a reverse proxy which is resolving which web app should process the request based on the custom domain in Azure and I am pretty sure that's our problem but I am not very familiar with Azure architecture and don't know what to do.

P.S. If we use a custom header and set there the host name and reconfigure the API to use this custom request header everything works fine, but that's not what we want.

So any help would be of great help.

Answer 1

SO my problem was in the Virtual Box settings. it did not allow the VM to connect.

I solved it by:

Open settings in Virtual Box -> Network -> Attached to and choose Bridge Adapter from drop down

also click on Advanced in the network tab.

then click on Promiscuous Mode and choose Allow all.