Allow send custom location from server

[iMuFeng]

No description provided.

[vercel]

@iMuFeng is attempting to deploy a commit to the umami-software Team on Vercel.

A member of the Team first needs to authorize it.

[mikecao]

Other than Vercel and Cloudflare, are there other providers that offer headers?

[iMuFeng]

Scenario: We have two services - an API server and a Umami server, both using Cloudflare Proxied DNS.

When sending events from the API server to the Umami API, we need Umami to receive the client's IP address instead of the API server's IP address. To achieve this, we must:

1. Set an environment variable in Umami: CLIENT_IP_HEADER = x-forwarded-for
2. Include the header: x-forwarded-for = client's IP in the request

Without these settings, Umami's detection logic would prioritize getting the API server's IP address.

After setting CLIENT_IP_HEADER = x-forwarded-for, Umami can now successfully obtain the client's IP address. However, there's another issue: Umami's location detection code bypasses the IP-based location lookup and directly uses the cf-ipcountry header. Since Umami also uses Cloudflare Proxied DNS, this means the location information will always correspond to the API server's location rather than the client's.

We need to forward the location information provided by Cloudflare to Umami, so I've added three additional environment variables.

'x-forwarded-for': ip,
'x-ipcountry': req.header('cf-ipcountry'),
'x-ipregion-code': req.header('cf-region-code'),
'x-ipcity': req.header('cf-ipcity')

[mikecao]

How about we create an environment variable IGNORE_LOCATION_HEADERS, if set then it will skip the CF/Vercel sections and fall back to using the IP database.