Consider X-Forwarded-Host / Forwarded when capturing server.address and server.port

Author: trask

CHANGELOG.md

@@ -11,6 +11,8 @@ release.
 
 - BREAKING: Rename http.resend_count to http.request.resend_count.
   ([#374](https://github.com/open-telemetry/semantic-conventions/pull/374))
+- BREAKING: Consider `X-Forwarded-Host` / `Forwarded` when capturing `server.address` and `server.port`.
+  ([#999](https://github.com/open-telemetry/semantic-conventions/pull/999))
 
 ### Features
 

docs/http/http-metrics.md

@@ -131,6 +131,8 @@ SHOULD include the [application root](/docs/http/http-spans.md#http-server-defin
   include host identifier.
 - Host identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Host identifier of the `Host` header
 
 SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.
@@ -140,6 +142,8 @@ SHOULD NOT be set if only IP address is available and capturing name would requi
 - Port identifier of the [primary server host](/docs/http/http-spans.md#http-server-definitions) of the matched virtual host.
 - Port identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Port identifier of the `Host` header
 
 `error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
@@ -310,6 +314,8 @@ SHOULD include the [application root](/docs/http/http-spans.md#http-server-defin
   include host identifier.
 - Host identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Host identifier of the `Host` header
 
 SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.
@@ -319,6 +325,8 @@ SHOULD NOT be set if only IP address is available and capturing name would requi
 - Port identifier of the [primary server host](/docs/http/http-spans.md#http-server-definitions) of the matched virtual host.
 - Port identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Port identifier of the `Host` header
 
 `error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
@@ -415,6 +423,8 @@ SHOULD include the [application root](/docs/http/http-spans.md#http-server-defin
   include host identifier.
 - Host identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Host identifier of the `Host` header
 
 SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.
@@ -424,6 +434,8 @@ SHOULD NOT be set if only IP address is available and capturing name would requi
 - Port identifier of the [primary server host](/docs/http/http-spans.md#http-server-definitions) of the matched virtual host.
 - Port identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Port identifier of the `Host` header
 
 `error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.

docs/http/http-spans.md

@@ -393,6 +393,8 @@ SHOULD include the [application root](/docs/http/http-spans.md#http-server-defin
   include host identifier.
 - Host identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Host identifier of the `Host` header
 
 SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.
@@ -402,6 +404,8 @@ SHOULD NOT be set if only IP address is available and capturing name would requi
 - Port identifier of the [primary server host](/docs/http/http-spans.md#http-server-definitions) of the matched virtual host.
 - Port identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
   if it's sent in absolute-form.
+- Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+  [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
 - Port identifier of the `Host` header
 
 **[6]:** If not default (`80` for `http` scheme, `443` for `https`).

model/http-common.yaml

@@ -81,6 +81,8 @@ groups:
             include host identifier.
           - Host identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
             if it's sent in absolute-form.
+          - Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+            [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
           - Host identifier of the `Host` header
 
           SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.
@@ -94,6 +96,8 @@ groups:
           - Port identifier of the [primary server host](/docs/http/http-spans.md#http-server-definitions) of the matched virtual host.
           - Port identifier of the [request target](https://www.rfc-editor.org/rfc/rfc9110.html#target.resource)
             if it's sent in absolute-form.
+          - Host identifier of [Forwarded#host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded#host),
+            [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host), or a similar header.
           - Port identifier of the `Host` header
         requirement_level:
           conditionally_required: If not default (`80` for `http` scheme, `443` for `https`).