Adding extra fields to access logging

Linkerd access logs are missing the origin IP address.

Solved by adding in the field x_forwarded_for to access logs which has the origin ip address.

Validated by compiling and deploying the modified proxy image alongside a nginx container, checking access log content for existing fields + the new field

Part fixes issue #9842

Signed-off-by: Dan Ambrose <[email protected]>

Author: neoreddog

linkerd/http-access-log/src/lib.rs

@@ -133,6 +133,7 @@ where
             processing_ns = field::Empty,
             user_agent = get_header(http::header::USER_AGENT),
             host = get_header(http::header::HOST),
+            x_forwarded_for = get_header(http::header::HeaderName::from_static("x-forwarded-for"))
         );
 
         // The access log span is only enabled by the `tracing` subscriber if