Repository: imbolc/axum-client-ip (language: rust)

Issue:
doc: With FlyClientIp and health check enabled - provide header
Hello, This is excellent library everything works as documented. 

I have an existing app running on Fly.io with health check enabled. 

I integerated `axum-client-ip` for all paths and `FlyClientIp` as source for IP.  On deployment health check didnt pass -  of course because `axum-client-ip` returns 500 when it did not see the `Fly-Client-IP` header for health check.  

Headers for health check can be configured through [`services.http_checks.headers`](https://fly.io/docs/reference/configuration/#services-http_checks)

Perhaps it would help to document this somewhere in this repo? if so, I'm happy to send another PR if you think it would help next person and this repo is right place to document it. 

Thank you


Discussion / hints:
Hi :) Thanks, I guess everyone experiencing the issue would end up in `FlyClientIp` extractor  docs. Feel free to extend them, let me know if you see a more suitable place.

Fix patch:
diff --git a/src/rudimental.rs b/src/rudimental.rs
index c24afbd..16dfd34 100644
--- a/src/rudimental.rs
+++ b/src/rudimental.rs
@@ -47,6 +47,11 @@ pub struct XRealIp(pub IpAddr);
 
 /// Extracts a valid IP from `Fly-Client-IP` (Fly.io) header
 ///
+/// When [FlyClientIp] extractor is run for health check path,
+/// provide required `Fly-Client-IP` header through
+/// [`services.http_checks.headers`](https://fly.io/docs/reference/configuration/#services-http_checks)
+/// or [`http_service.checks.headers`](https://fly.io/docs/reference/configuration/#services-http_checks)
+///
 /// Rejects with a 500 error if the header is absent or the IP isn't valid
 #[derive(Debug)]
 pub struct FlyClientIp(pub IpAddr);


Test patch: