Compact: Fix web.prefix-header to use &wc.prefixHeaderName

CHANGELOG.md

@@ -13,6 +13,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 
 ### Added
 
+- [#3184](https://github.com/thanos-io/thanos/pull/3184) Compact: Fix web.prefix-header to use &wc.prefixHeaderName
 - [#3181](https://github.com/thanos-io/thanos/pull/3181) Logging: Add debug level logging for responses between 300-399
 - [#3133](https://github.com/thanos-io/thanos/pull/3133) Query: Allow passing a `storeMatch[]` to Labels APIs. Also time range metadata based store filtering is supported on Labels APIs.
 - [#3154](https://github.com/thanos-io/thanos/pull/3154) Query Frontend: Add metric `thanos_memcached_getmulti_gate_queries_max`.

cmd/thanos/config.go

@@ -153,6 +153,6 @@ func (wc *webConfig) registerFlag(cmd extkingpin.FlagClause) *webConfig {
 		"Static prefix for all HTML links and redirect URLs in the bucket web UI interface. Actual endpoints are still served on / or the web.route-prefix. This allows thanos bucket web UI to be served behind a reverse proxy that strips a URL sub-path.").
 		Default("").StringVar(&wc.externalPrefix)
 	cmd.Flag("web.prefix-header", "Name of HTTP request header used for dynamic prefixing of UI links and redirects. This option is ignored if web.external-prefix argument is set. Security risk: enable this option only if a reverse proxy in front of thanos is resetting the header. The --web.prefix-header=X-Forwarded-Prefix option can be useful, for example, if Thanos UI is served via Traefik reverse proxy with PathPrefixStrip option enabled, which sends the stripped prefix value in X-Forwarded-Prefix header. This allows thanos UI to be served on a sub-path.").
-		Default("").StringVar(&wc.externalPrefix)
+		Default("").StringVar(&wc.prefixHeaderName)
 	return wc
 }