Cleanup Connection headers before passing the middleware chain

Co-authored-by: Romain <rtribotte@users.noreply.github.com>

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

@@ -111,6 +111,9 @@ Entry point address.
 `--entrypoints.<name>.allowacmebypass`:  
 Enables handling of ACME TLS and HTTP challenges with custom routers. (Default: ```false```)
 
+`--entrypoints.<name>.forwardedheaders.connection`:  
+List of Connection headers that are allowed to pass through the middleware chain before being removed.
+
 `--entrypoints.<name>.forwardedheaders.insecure`:  
 Trust all forwarded headers. (Default: ```false```)
 

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

@@ -111,6 +111,9 @@ Entry point address.
 `TRAEFIK_ENTRYPOINTS_<NAME>_ALLOWACMEBYPASS`:  
 Enables handling of ACME TLS and HTTP challenges with custom routers. (Default: ```false```)
 
+`TRAEFIK_ENTRYPOINTS_<NAME>_FORWARDEDHEADERS_CONNECTION`:  
+List of Connection headers that are allowed to pass through the middleware chain before being removed.
+
 `TRAEFIK_ENTRYPOINTS_<NAME>_FORWARDEDHEADERS_INSECURE`:  
 Trust all forwarded headers. (Default: ```false```)
 

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

@@ -33,6 +33,7 @@
     [entryPoints.EntryPoint0.forwardedHeaders]
       insecure = true
       trustedIPs = ["foobar", "foobar"]
+      connection = ["foobar", "foobar"]
     [entryPoints.EntryPoint0.http]
       middlewares = ["foobar", "foobar"]
       encodeQuerySemicolons = true

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

@@ -37,6 +37,9 @@ entryPoints:
       trustedIPs:
         - foobar
         - foobar
+      connection:
+        - foobar
+        - foobar
     http:
       redirections:
         entryPoint: