Add a generic proxier

To proxy traffic to anything that implements ResourceLocation. Currently, this is only services. This is easily extensible to minions (would supercede existing mechanism) and pods.
2025-09-10 13:42:02 +00:00 · 2014-08-27 16:10:44 -07:00
parent e4cd06d2b9
commit e2b645ec15
8 changed files with 334 additions and 4 deletions
--- a/pkg/apiserver/proxy.go
+++ b/pkg/apiserver/proxy.go
@@ -0,0 +1,188 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package apiserver
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"path"
+	"strings"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/httplog"
+
+	"code.google.com/p/go.net/html"
+	"code.google.com/p/go.net/html/atom"
+	"github.com/golang/glog"
+)
+
+type ProxyHandler struct {
+	prefix  string
+	storage map[string]RESTStorage
+	codec   Codec
+}
+
+func (r *ProxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	parts := strings.SplitN(req.URL.Path, "/", 3)
+	if len(parts) < 2 {
+		notFound(w, req)
+		return
+	}
+	resourceName := parts[0]
+	id := parts[1]
+	rest := ""
+	if len(parts) == 3 {
+		rest = parts[2]
+	}
+	storage, ok := r.storage[resourceName]
+	if !ok {
+		httplog.LogOf(w).Addf("'%v' has no storage object", resourceName)
+		notFound(w, req)
+		return
+	}
+
+	redirector, ok := storage.(Redirector)
+	if !ok {
+		httplog.LogOf(w).Addf("'%v' is not a redirector", resourceName)
+		notFound(w, req)
+		return
+	}
+
+	location, err := redirector.ResourceLocation(id)
+	if err != nil {
+		status := errToAPIStatus(err)
+		writeJSON(status.Code, r.codec, status, w)
+		return
+	}
+
+	destURL, err := url.Parse(location)
+	if err != nil {
+		status := errToAPIStatus(err)
+		writeJSON(status.Code, r.codec, status, w)
+		return
+	}
+	destURL.Path = rest
+	destURL.RawQuery = req.URL.RawQuery
+	newReq, err := http.NewRequest(req.Method, destURL.String(), req.Body)
+	if err != nil {
+		glog.Errorf("Failed to create request: %s", err)
+	}
+	newReq.Header = req.Header
+
+	proxy := httputil.NewSingleHostReverseProxy(&url.URL{Scheme: "http", Host: destURL.Host})
+	proxy.Transport = &proxyTransport{
+		proxyScheme:      req.URL.Scheme,
+		proxyHost:        req.URL.Host,
+		proxyPathPrepend: path.Join(r.prefix, resourceName, id),
+	}
+	proxy.ServeHTTP(w, newReq)
+}
+
+type proxyTransport struct {
+	proxyScheme      string
+	proxyHost        string
+	proxyPathPrepend string
+}
+
+func (t *proxyTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	resp, err := http.DefaultTransport.RoundTrip(req)
+
+	if err != nil {
+		message := err.Error() + "\n" + req.URL.String()
+		if strings.Contains(err.Error(), "connection refused") {
+			message = fmt.Sprintf("Failed to connect to %s (%s)", req.URL.Host, err)
+		}
+		resp = &http.Response{
+			StatusCode: http.StatusServiceUnavailable,
+			Body:       ioutil.NopCloser(strings.NewReader(message)),
+		}
+		return resp, nil
+	}
+
+	if resp.Header.Get("Content-Type") != "text/html" {
+		// Do nothing, simply pass through
+		return resp, err
+	}
+
+	resp, err = t.fixLinks(req, resp)
+	return resp, err
+}
+
+// fixLinks modifies links in an HTML file such that they will be redirected through the proxy if needed.
+func (t *proxyTransport) fixLinks(req *http.Request, resp *http.Response) (*http.Response, error) {
+	body, err := ioutil.ReadAll(resp.Body)
+	resp.Body.Close()
+	if err != nil {
+		// copying the response body did not work
+		return nil, err
+	}
+
+	bodyNode := &html.Node{
+		Type:     html.ElementNode,
+		Data:     "body",
+		DataAtom: atom.Body,
+	}
+	nodes, err := html.ParseFragment(bytes.NewBuffer(body), bodyNode)
+	if err != nil {
+		glog.Errorf("Failed to found <body> node: %v", err)
+		return resp, err
+	}
+
+	// Define the method to traverse the doc tree and update href node to
+	// point to correct minion
+	var updateHRef func(*html.Node)
+	updateHRef = func(n *html.Node) {
+		if n.Type == html.ElementNode && n.Data == "a" {
+			for i, attr := range n.Attr {
+				if attr.Key == "href" {
+					url, err := url.Parse(attr.Val)
+					if err != nil {
+						continue
+					}
+					url.Scheme = t.proxyScheme
+					url.Host = t.proxyHost
+					url.Path = path.Join(t.proxyPathPrepend, path.Dir(req.URL.Path), url.Path, "/")
+					n.Attr[i].Val = url.String()
+					break
+				}
+			}
+		}
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			updateHRef(c)
+		}
+	}
+
+	newContent := &bytes.Buffer{}
+	for _, n := range nodes {
+		updateHRef(n)
+		err = html.Render(newContent, n)
+		if err != nil {
+			glog.Errorf("Failed to render: %v", err)
+		}
+	}
+
+	resp.Body = ioutil.NopCloser(newContent)
+	// Update header node with new content-length
+	// TODO: Remove any hash/signature headers here?
+	resp.Header.Del("Content-Length")
+	resp.ContentLength = int64(newContent.Len())
+
+	return resp, err
+}