go.etcd.io/etcd@v3.3.27+incompatible/contrib/raftexample/httpapi.go (about)

     1  // Copyright 2015 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package main
    16  
    17  import (
    18  	"io/ioutil"
    19  	"log"
    20  	"net/http"
    21  	"strconv"
    22  
    23  	"github.com/coreos/etcd/raft/raftpb"
    24  )
    25  
    26  // Handler for a http based key-value store backed by raft
    27  type httpKVAPI struct {
    28  	store       *kvstore
    29  	confChangeC chan<- raftpb.ConfChange
    30  }
    31  
    32  func (h *httpKVAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    33  	key := r.RequestURI
    34  	switch {
    35  	case r.Method == "PUT":
    36  		v, err := ioutil.ReadAll(r.Body)
    37  		if err != nil {
    38  			log.Printf("Failed to read on PUT (%v)\n", err)
    39  			http.Error(w, "Failed on PUT", http.StatusBadRequest)
    40  			return
    41  		}
    42  
    43  		h.store.Propose(key, string(v))
    44  
    45  		// Optimistic-- no waiting for ack from raft. Value is not yet
    46  		// committed so a subsequent GET on the key may return old value
    47  		w.WriteHeader(http.StatusNoContent)
    48  	case r.Method == "GET":
    49  		if v, ok := h.store.Lookup(key); ok {
    50  			w.Write([]byte(v))
    51  		} else {
    52  			http.Error(w, "Failed to GET", http.StatusNotFound)
    53  		}
    54  	case r.Method == "POST":
    55  		url, err := ioutil.ReadAll(r.Body)
    56  		if err != nil {
    57  			log.Printf("Failed to read on POST (%v)\n", err)
    58  			http.Error(w, "Failed on POST", http.StatusBadRequest)
    59  			return
    60  		}
    61  
    62  		nodeId, err := strconv.ParseUint(key[1:], 0, 64)
    63  		if err != nil {
    64  			log.Printf("Failed to convert ID for conf change (%v)\n", err)
    65  			http.Error(w, "Failed on POST", http.StatusBadRequest)
    66  			return
    67  		}
    68  
    69  		cc := raftpb.ConfChange{
    70  			Type:    raftpb.ConfChangeAddNode,
    71  			NodeID:  nodeId,
    72  			Context: url,
    73  		}
    74  		h.confChangeC <- cc
    75  
    76  		// As above, optimistic that raft will apply the conf change
    77  		w.WriteHeader(http.StatusNoContent)
    78  	case r.Method == "DELETE":
    79  		nodeId, err := strconv.ParseUint(key[1:], 0, 64)
    80  		if err != nil {
    81  			log.Printf("Failed to convert ID for conf change (%v)\n", err)
    82  			http.Error(w, "Failed on DELETE", http.StatusBadRequest)
    83  			return
    84  		}
    85  
    86  		cc := raftpb.ConfChange{
    87  			Type:   raftpb.ConfChangeRemoveNode,
    88  			NodeID: nodeId,
    89  		}
    90  		h.confChangeC <- cc
    91  
    92  		// As above, optimistic that raft will apply the conf change
    93  		w.WriteHeader(http.StatusNoContent)
    94  	default:
    95  		w.Header().Set("Allow", "PUT")
    96  		w.Header().Add("Allow", "GET")
    97  		w.Header().Add("Allow", "POST")
    98  		w.Header().Add("Allow", "DELETE")
    99  		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
   100  	}
   101  }
   102  
   103  // serveHttpKVAPI starts a key-value server with a GET/PUT API and listens.
   104  func serveHttpKVAPI(kv *kvstore, port int, confChangeC chan<- raftpb.ConfChange, errorC <-chan error) {
   105  	srv := http.Server{
   106  		Addr: ":" + strconv.Itoa(port),
   107  		Handler: &httpKVAPI{
   108  			store:       kv,
   109  			confChangeC: confChangeC,
   110  		},
   111  	}
   112  	go func() {
   113  		if err := srv.ListenAndServe(); err != nil {
   114  			log.Fatal(err)
   115  		}
   116  	}()
   117  
   118  	// exit when raft goes down
   119  	if err, ok := <-errorC; ok {
   120  		log.Fatal(err)
   121  	}
   122  }