mirror of
https://github.com/etcd-io/etcd.git
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122 lines
3.6 KiB
Go
122 lines
3.6 KiB
Go
// Copyright 2015 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package httpproxy
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import (
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"encoding/json"
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"net/http"
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"strings"
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"time"
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"go.uber.org/zap"
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"golang.org/x/net/http2"
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)
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const (
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// DefaultMaxIdleConnsPerHost indicates the default maximum idle connection
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// count maintained between proxy and each member. We set it to 128 to
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// let proxy handle 128 concurrent requests in long term smoothly.
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// If the number of concurrent requests is bigger than this value,
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// proxy needs to create one new connection when handling each request in
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// the delta, which is bad because the creation consumes resource and
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// may eat up ephemeral ports.
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DefaultMaxIdleConnsPerHost = 128
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)
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// GetProxyURLs is a function which should return the current set of URLs to
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// which client requests should be proxied. This function will be queried
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// periodically by the proxy Handler to refresh the set of available
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// backends.
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type GetProxyURLs func() []string
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// NewHandler creates a new HTTP handler, listening on the given transport,
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// which will proxy requests to an etcd cluster.
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// The handler will periodically update its view of the cluster.
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func NewHandler(lg *zap.Logger, t *http.Transport, urlsFunc GetProxyURLs, failureWait time.Duration, refreshInterval time.Duration) http.Handler {
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if lg == nil {
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lg = zap.NewNop()
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}
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if t.TLSClientConfig != nil {
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// Enable http2, see Issue 5033.
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err := http2.ConfigureTransport(t)
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if err != nil {
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lg.Info("Error enabling Transport HTTP/2 support", zap.Error(err))
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}
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}
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p := &reverseProxy{
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lg: lg,
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director: newDirector(lg, urlsFunc, failureWait, refreshInterval),
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transport: t,
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}
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mux := http.NewServeMux()
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mux.Handle("/", p)
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mux.HandleFunc("/v2/config/local/proxy", p.configHandler)
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return mux
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}
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// NewReadonlyHandler wraps the given HTTP handler to allow only GET requests
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func NewReadonlyHandler(hdlr http.Handler) http.Handler {
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readonly := readonlyHandlerFunc(hdlr)
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return http.HandlerFunc(readonly)
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}
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func readonlyHandlerFunc(next http.Handler) func(http.ResponseWriter, *http.Request) {
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return func(w http.ResponseWriter, req *http.Request) {
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if req.Method != "GET" {
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w.WriteHeader(http.StatusNotImplemented)
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return
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}
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next.ServeHTTP(w, req)
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}
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}
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func (p *reverseProxy) configHandler(w http.ResponseWriter, r *http.Request) {
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if !allowMethod(w, r.Method, "GET") {
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return
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}
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eps := p.director.endpoints()
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epstr := make([]string, len(eps))
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for i, e := range eps {
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epstr[i] = e.URL.String()
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}
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proxyConfig := struct {
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Endpoints []string `json:"endpoints"`
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}{
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Endpoints: epstr,
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}
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json.NewEncoder(w).Encode(proxyConfig)
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}
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// allowMethod verifies that the given method is one of the allowed methods,
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// and if not, it writes an error to w. A boolean is returned indicating
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// whether or not the method is allowed.
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func allowMethod(w http.ResponseWriter, m string, ms ...string) bool {
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for _, meth := range ms {
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if m == meth {
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return true
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}
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}
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w.Header().Set("Allow", strings.Join(ms, ","))
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http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
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return false
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}
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