Cannot run devcontainer with company proxy

[olijaun]

I'm trying to run https://github.com/microsoft/vscode-remote-try-rust

However I can't get it working inside my company because of a proxy problem. It's an authenticating proxy. I modified the Dockerfile and set the environment variables HTTP_PROXY and HTTPS_PROXY to my company's proxy in the format http://user:password@proxy:8080

However then the following fails:

    Failed to download VS Code Server
    (https://update.code.visualstudio.com/commit:cfa2e218100323074ac1948c885448fdf4de2a7f/server-linux- 
    x64/stable): HTTP 407 - authenticationrequired

I'm not sure what is missing. I can confirm that HTTP_PROXY and HTTPS_PROXY are properly set inside the container because I've checked it using

    echo $HTTP_PROXY

I think it would be very helpful if proxy set up was documented becasue it is quite common inside bigger companies.

Regards
Oliver