[Bug]: Image pull/push doesn't work for all proxy environment variables. #578

I have done the following

• I have searched the existing issues
• If possible, I've reproduced the issue using the 'main' branch of this project

Steps to reproduce

See #466 and containerization#255 for details.

Should be able to observe this by setting http_proxy and running container image pull or container image push, and noticing no effect.

Current behavior

The only proxy variable currently checked is HTTP_PROXY, uppercase only. The proxy URL is used for all requests, which is incorrect.

Expected behavior

Image pull should honor the proxy environment variables as described in https://about.gitlab.com/blog/we-need-to-talk-no-proxy/.

Environment

- OS: macOS 26.0 Beta
- Xcode: 26 beta
- Container: 0.4.1

Relevant log output

Code of Conduct

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