working version

.gitignore

@@ -34,3 +34,4 @@ go.mod
 go.sum
 index.html
 dist
+caddy/caddy

caddywebp.go

@@ -57,9 +57,11 @@ func (s Webp) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.H
 		return next.ServeHTTP(w, r)
 	}
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
-	rootPath,_:=repl.GetString("{http.vars.root}")
-	cacheFile:=fmt.Sprintf("%s%s",caddyhttp.SanitizedPathJoin(rootPath + "/.webpcache/", r.URL.Path +"?" + r.URL.RawQuery))
-	origFile:=caddyhttp.SanitizedPathJoin(rootPath, r.URL.Path)
+
+	root := repl.ReplaceAll("{http.vars.root}", ".")
+	cacheFile:=fmt.Sprintf("%s%s",caddyhttp.SanitizedPathJoin(root + "/.webpcache/", r.URL.Path +"?"), r.URL.RawQuery)
+	origFile := caddyhttp.SanitizedPathJoin(root, r.URL.Path)
+
 	cstat, err:=os.Stat(cacheFile)
 	if err==nil {
 		// Cache file exists
@@ -70,7 +72,7 @@ func (s Webp) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.H
 			if err == nil {
 				// We couldn't open for whatever reason so let's not serve it
 				w.Header().Set("content-type", "image/webp")
-				w.Header().Set("webpstatus", "fromcache")
+				w.Header().Add("webpstatus", "fromcache")
 				w.WriteHeader(http.StatusOK)
 				io.Copy(w,fh)
 				return nil
@@ -82,7 +84,7 @@ func (s Webp) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.H
 	cachePath,_:=path.Split(cacheFile)
 	_,err=os.Stat(cachePath)
 	if err != nil {
-		err=os.Mkdir(cachePath, 0600)
+		err=os.MkdirAll(cachePath, 0600)
 		if err != nil {
 			log.Printf("Creating cache path: " + err.Error())
 		}
@@ -128,7 +130,9 @@ func (s Webp) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.H
 
 	buf.WriteTo(fh)
 	fh.Close()
-	w.Header().Set("Content-Type", "image/webp")
+	w.Header().Set("content-Type", "image/webp")
+	w.Header().Add("webpstatus", "tocache")
+
 	w.WriteHeader(http.StatusOK)
 	buf.WriteTo(w)
 	return nil