Add generic path rewrite middleware

And fix a bug in the logging middleware.

common/middleware/logging.go

@@ -14,9 +14,10 @@ import (
 var Logging = Func(func(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		begin := time.Now()
+		uri := r.RequestURI // capture the URI before running next, as it may get rewritten
 		i := &interceptor{ResponseWriter: w, statusCode: http.StatusOK}
 		next.ServeHTTP(i, r)
-		log.Infof("%s %s (%d) %s", r.Method, r.RequestURI, i.statusCode, time.Since(begin))
+		log.Infof("%s %s (%d) %s", r.Method, uri, i.statusCode, time.Since(begin))
 	})
 })
 

common/middleware/path_rewrite.go

@@ -0,0 +1,26 @@
+package middleware
+
+import (
+	"net/http"
+	"regexp"
+)
+
+// PathRewrite supports regex matching and replace on Request URIs
+func PathRewrite(regexp *regexp.Regexp, replacement string) Interface {
+	return pathRewrite{
+		regexp:      regexp,
+		replacement: replacement,
+	}
+}
+
+type pathRewrite struct {
+	regexp      *regexp.Regexp
+	replacement string
+}
+
+func (p pathRewrite) Wrap(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		r.RequestURI = p.regexp.ReplaceAllString(r.RequestURI, p.replacement)
+		next.ServeHTTP(w, r)
+	})
+}