From 937cfacc01c0acd27f352f1f57b8abd6f1e8bc56 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Sat, 23 Jan 2021 03:43:48 -0800
Subject: [PATCH] filer: add "proxyToFileId" to reverse proxy to a volume
 server

---
 weed/server/filer_server_handlers.go       | 13 ++++-
 weed/server/filer_server_handlers_proxy.go | 66 ++++++++++++++++++++++
 2 files changed, 76 insertions(+), 3 deletions(-)
 create mode 100644 weed/server/filer_server_handlers_proxy.go

diff --git a/weed/server/filer_server_handlers.go b/weed/server/filer_server_handlers.go
index 451e2a2de..5b93c6d08 100644
--- a/weed/server/filer_server_handlers.go
+++ b/weed/server/filer_server_handlers.go
@@ -17,9 +17,16 @@ func (fs *FilerServer) filerHandler(w http.ResponseWriter, r *http.Request) {
 	start := time.Now()
 	switch r.Method {
 	case "GET":
-		stats.FilerRequestCounter.WithLabelValues("get").Inc()
-		fs.GetOrHeadHandler(w, r, true)
-		stats.FilerRequestHistogram.WithLabelValues("get").Observe(time.Since(start).Seconds())
+		fileId := r.FormValue("proxyToFileId")
+		if fileId != "" {
+			stats.FilerRequestCounter.WithLabelValues("proxy").Inc()
+			fs.proxyToVolumeServer(w,r,fileId)
+			stats.FilerRequestHistogram.WithLabelValues("proxy").Observe(time.Since(start).Seconds())
+		} else {
+			stats.FilerRequestCounter.WithLabelValues("get").Inc()
+			fs.GetOrHeadHandler(w, r, true)
+			stats.FilerRequestHistogram.WithLabelValues("get").Observe(time.Since(start).Seconds())
+		}
 	case "HEAD":
 		stats.FilerRequestCounter.WithLabelValues("head").Inc()
 		fs.GetOrHeadHandler(w, r, false)
diff --git a/weed/server/filer_server_handlers_proxy.go b/weed/server/filer_server_handlers_proxy.go
new file mode 100644
index 000000000..5ba42e71d
--- /dev/null
+++ b/weed/server/filer_server_handlers_proxy.go
@@ -0,0 +1,66 @@
+package weed_server
+
+import (
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"io"
+	"math/rand"
+	"net/http"
+)
+
+var (
+	client *http.Client
+)
+
+func init() {
+	client = &http.Client{Transport: &http.Transport{
+		MaxIdleConnsPerHost: 1024,
+	}}
+}
+
+func (fs *FilerServer) proxyToVolumeServer(w http.ResponseWriter, r *http.Request, fileId string) {
+
+	urlStrings, err := fs.filer.MasterClient.GetLookupFileIdFunction()(fileId)
+	if err != nil {
+		glog.Errorf("locate %s: %v", fileId, err)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	if len(urlStrings) == 0 {
+		w.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	proxyReq, err := http.NewRequest("GET", urlStrings[rand.Intn(len(urlStrings))], r.Body)
+	if err != nil {
+		glog.Errorf("NewRequest %s: %v", urlStrings[0], err)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	proxyReq.Header.Set("Host", r.Host)
+	proxyReq.Header.Set("X-Forwarded-For", r.RemoteAddr)
+
+	for header, values := range r.Header {
+		for _, value := range values {
+			proxyReq.Header.Add(header, value)
+		}
+	}
+
+	proxyResponse, postErr := client.Do(proxyReq)
+
+	if postErr != nil {
+		glog.Errorf("post to filer: %v", postErr)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+	defer util.CloseResponse(proxyResponse)
+
+	for k, v := range proxyResponse.Header {
+		w.Header()[k] = v
+	}
+	w.WriteHeader(proxyResponse.StatusCode)
+	io.Copy(w, proxyResponse.Body)
+
+}