🚀 Feature Request: Make CF-Connecting-IP header available in dev mode locally

[godfat]

Problem statement

The application is behind a reverse proxy, and it cannot access the client IP. All the application sees is the IP from wrangler, because it doesn't add CF-Connecting-IP, nor does it append the client IP to X-Forwarded-For.

Feature request

• Have header CF-Connecting-IP available. Or:
• Append the client IP to X-Forwarded-For. Or:
• Have a way to access the client IP, for example, it can be done via request.socket.remoteAddress

Background

We (GitLab) need a way to access the client IP when running wrangler for end-to-end tests. We do not want to deploy it to Cloudflare in order to run end-to-end tests.

This is needed for the end-to-end tests because the application which wrangler is talking to is behind another reverse proxy, and given this the application sees only the wrangler IP, not the actual client IP. This looks like this:

client <-> wrangler <-> (optional nginx) <-> workhorse <-> application

We want wrangler to append the client IP in X-Forwarded-For header and configure wrangler's IP as a trusted proxy, so that the application can find the real IP from X-Forwarded-For.

If CF-Connecting-IP is always available and can be trusted, then we can use that as well.

The main point is that we need to have a way to access the client IP, so that we can test features with regard to restricting IP. At the moment all IPs we can see are from wrangler itself, which means we cannot test this.

Workaround

We can potentially run another Nginx in front of wrangler to append the IP to X-Forwarded-For, like this:

client <-> nginx <-> wrangler <-> (optional nginx) <-> workhorse <-> application

But due to all the complexity involved with this, it would be nice to avoid needing to do this, just for accessing the client IP.

References

• This issue described what we want to do: https://gitlab.com/gitlab-org/cells/http-router/-/issues/140
• This issue described the original problem we want to solve: https://gitlab.com/gitlab-org/gitlab/-/issues/499657