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minionproxy.go
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/
minionproxy.go
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/*
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"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"code.google.com/p/go.net/html"
"code.google.com/p/go.net/html/atom"
"github.com/golang/glog"
)
// TODO: replace with proxy handler on minions
func handleProxyMinion(w http.ResponseWriter, req *http.Request) {
path := strings.TrimLeft(req.URL.Path, "/")
rawQuery := req.URL.RawQuery
// Expect path as: ${minion}/${query_to_minion}
// and query_to_minion can be any query that kubelet will accept.
//
// For example:
// To query stats of a minion or a pod or a container,
// path string can be ${minion}/stats/<podid>/<containerName> or
// ${minion}/podInfo?podID=<podid>
//
// To query logs on a minion, path string can be:
// ${minion}/logs/
parts := strings.SplitN(path, "/", 2)
if len(parts) != 2 {
badGatewayError(w, req)
return
}
minionHost := parts[0]
_, port, _ := net.SplitHostPort(minionHost)
if port == "" {
// Couldn't retrieve port information
// TODO: Retrieve port info from a common object
minionHost += ":10250"
}
minionPath := "/" + parts[1]
minionURL := &url.URL{
Scheme: "http",
Host: minionHost,
}
newReq, err := http.NewRequest("GET", minionPath+"?"+rawQuery, nil)
if err != nil {
glog.Errorf("Failed to create request: %s", err)
}
proxy := httputil.NewSingleHostReverseProxy(minionURL)
proxy.Transport = &minionTransport{}
proxy.ServeHTTP(w, newReq)
}
type minionTransport struct{}
func (t *minionTransport) RoundTrip(req *http.Request) (*http.Response, error) {
resp, err := http.DefaultTransport.RoundTrip(req)
if err != nil {
if strings.Contains(err.Error(), "connection refused") {
message := fmt.Sprintf("Failed to connect to minion:%s", req.URL.Host)
resp = &http.Response{
StatusCode: http.StatusServiceUnavailable,
Body: ioutil.NopCloser(strings.NewReader(message)),
}
return resp, nil
}
return nil, err
}
if strings.Contains(resp.Header.Get("Content-Type"), "text/plain") {
// Do nothing, simply pass through
return resp, err
}
resp, err = t.ProcessResponse(req, resp)
return resp, err
}
func (t *minionTransport) ProcessResponse(req *http.Request, resp *http.Response) (*http.Response, error) {
body, err := ioutil.ReadAll(resp.Body)
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 := &url.URL{
Path: "/proxy/minion/" + req.URL.Host + req.URL.Path + attr.Val,
}
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
}