What version of Go are you using (go version)?

Playground depends upon docker build. I'm using the default build args.

$ github.com/golang/playground@master

What did you do?

Install the go playground inside my company VPN. I wrote a playground program that used internal only libraries.

What did you expect to see?

I expected my program to run.

What did you see instead?

The playground was unable to run my code.

The playground code hardcodes https://github.com/golang/playground/blob/a7b4d4c4bb72efd2ec20c9f30d5c1e6f09cee3d2/sandbox.go#L373 GOPROXY=https://proxy.golang.org.

I forked the playground code and replace GOPROXY=https://proxy.golang.org. with our company's internal athen's proxy GOPROXY=https://proxy.mycompany.intranet. . I was then able to use my company's internal software.

I would propose that the playground's Dockerfile https://github.com/golang/playground/blob/master/Dockerfile accept GOPROXY as an environment variable that configures where the playground uses the proxy