Add captured headers options for tracing

Co-authored-by: Baptiste Mayelle <baptiste.mayelle@traefik.io>

docs/content/reference/static-configuration/cli-ref.md

@@ -1017,6 +1017,12 @@ OpenTracing configuration. (Default: ```false```)
 `--tracing.addinternals`:  
 Enables tracing for internal services (ping, dashboard, etc...). (Default: ```false```)
 
+`--tracing.capturedrequestheaders`:  
+Request headers to add as attributes for server and client spans.
+
+`--tracing.capturedresponseheaders`:  
+Response headers to add as attributes for server and client spans.
+
 `--tracing.globalattributes.<name>`:  
 Defines additional attributes (key:value) on all spans.
 

docs/content/reference/static-configuration/env-ref.md

@@ -1017,6 +1017,12 @@ OpenTracing configuration. (Default: ```false```)
 `TRAEFIK_TRACING_ADDINTERNALS`:  
 Enables tracing for internal services (ping, dashboard, etc...). (Default: ```false```)
 
+`TRAEFIK_TRACING_CAPTUREDREQUESTHEADERS`:  
+Request headers to add as attributes for server and client spans.
+
+`TRAEFIK_TRACING_CAPTUREDRESPONSEHEADERS`:  
+Response headers to add as attributes for server and client spans.
+
 `TRAEFIK_TRACING_GLOBALATTRIBUTES_<NAME>`:  
 Defines additional attributes (key:value) on all spans.
 

docs/content/reference/static-configuration/file.toml

@@ -380,6 +380,8 @@
 
 [tracing]
   serviceName = "foobar"
+  capturedRequestHeaders = ["foobar", "foobar"]
+  capturedResponseHeaders = ["foobar", "foobar"]
   sampleRate = 42.0
   addInternals = true
   [tracing.globalAttributes]

docs/content/reference/static-configuration/file.yaml

@@ -418,6 +418,12 @@ tracing:
   globalAttributes:
     name0: foobar
     name1: foobar
+  capturedRequestHeaders:
+    - foobar
+    - foobar
+  capturedResponseHeaders:
+    - foobar
+    - foobar
   sampleRate: 42
   addInternals: true
   otlp: