contrib/raftexample: Allow nodes to be added to a running cluster
A node with ID n can be added by POSTing the new node's URL to /n on the HTTP server.release-2.3
parent
7d862960cc
commit
7c0b6d9be9
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@ -19,11 +19,14 @@ import (
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"log"
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"net/http"
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"strconv"
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"github.com/coreos/etcd/raft/raftpb"
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)
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// Handler for a http based key-value store backed by raft
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type httpKVAPI struct {
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store *kvstore
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confChangeC chan<- raftpb.ConfChange
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}
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func (h *httpKVAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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@ -48,18 +51,48 @@ func (h *httpKVAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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} else {
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http.Error(w, "Failed to GET", http.StatusNotFound)
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}
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case r.Method == "POST":
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url, err := ioutil.ReadAll(r.Body)
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if err != nil {
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log.Printf("Failed to read on POST (%v)\n", err)
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http.Error(w, "Failed on POST", http.StatusBadRequest)
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return
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}
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nodeId, err := strconv.ParseUint(key[1:], 0, 64)
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if err != nil {
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log.Printf("Failed to convert ID for conf change (%v)\n", err)
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http.Error(w, "Failed on POST", http.StatusBadRequest)
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return
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}
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cc := raftpb.ConfChange{
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Type: raftpb.ConfChangeAddNode,
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NodeID: nodeId,
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Context: url,
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}
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h.confChangeC <- cc
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// As above, optimistic that raft will apply the conf change
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w.WriteHeader(http.StatusNoContent)
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default:
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w.Header().Set("Allow", "PUT")
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w.Header().Add("Allow", "GET")
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w.Header().Add("Allow", "POST")
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http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
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}
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}
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// serveHttpKVAPI starts a key-value server with a GET/PUT API and listens.
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func serveHttpKVAPI(port int, proposeC chan<- string, commitC <-chan *string, errorC <-chan error) {
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func serveHttpKVAPI(port int, proposeC chan<- string, confChangeC chan<- raftpb.ConfChange,
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commitC <-chan *string, errorC <-chan error) {
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srv := http.Server{
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Addr: ":" + strconv.Itoa(port),
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Handler: &httpKVAPI{newKVStore(proposeC, commitC, errorC)},
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Handler: &httpKVAPI{
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store: newKVStore(proposeC, commitC, errorC),
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confChangeC: confChangeC,
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},
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}
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if err := srv.ListenAndServe(); err != nil {
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log.Fatal(err)
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@ -25,6 +25,7 @@ func main() {
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cluster := flag.String("cluster", "http://127.0.0.1:9021", "comma separated cluster peers")
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id := flag.Int("id", 1, "node ID")
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kvport := flag.Int("port", 9121, "key-value server port")
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join := flag.Bool("join", false, "join an existing cluster")
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flag.Parse()
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proposeC := make(chan string)
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@ -33,8 +34,8 @@ func main() {
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defer close(confChangeC)
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// raft provides a commit stream for the proposals from the http api
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commitC, errorC := newRaftNode(*id, strings.Split(*cluster, ","), proposeC, confChangeC)
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commitC, errorC := newRaftNode(*id, strings.Split(*cluster, ","), *join, proposeC, confChangeC)
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// the key-value http handler will propose updates to raft
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serveHttpKVAPI(*kvport, proposeC, commitC, errorC)
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serveHttpKVAPI(*kvport, proposeC, confChangeC, commitC, errorC)
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}
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@ -43,6 +43,7 @@ type raftNode struct {
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id int // client ID for raft session
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peers []string // raft peer URLs
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join bool // node is joining an existing cluster
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waldir string // path to WAL directory
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// raft backing for the commit/error channel
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@ -60,7 +61,7 @@ type raftNode struct {
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// provided the proposal channel. All log entries are replayed over the
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// commit channel, followed by a nil message (to indicate the channel is
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// current), then new log entries. To shutdown, close proposeC and read errorC.
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func newRaftNode(id int, peers []string, proposeC <-chan string,
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func newRaftNode(id int, peers []string, join bool, proposeC <-chan string,
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confChangeC <-chan raftpb.ConfChange) (<-chan *string, <-chan error) {
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rc := &raftNode{
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@ -70,6 +71,7 @@ func newRaftNode(id int, peers []string, proposeC <-chan string,
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errorC: make(chan error),
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id: id,
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peers: peers,
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join: join,
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waldir: fmt.Sprintf("raftexample-%d", id),
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raftStorage: raft.NewMemoryStorage(),
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stopc: make(chan struct{}),
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@ -186,7 +188,11 @@ func (rc *raftNode) startRaft() {
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if oldwal {
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rc.node = raft.RestartNode(c)
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} else {
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rc.node = raft.StartNode(c, rpeers)
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startPeers := rpeers
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if rc.join {
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startPeers = nil
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}
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rc.node = raft.StartNode(c, startPeers)
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}
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ss := &stats.ServerStats{}
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@ -49,7 +49,7 @@ func newCluster(n int) *cluster {
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os.RemoveAll(fmt.Sprintf("raftexample-%d", i+1))
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clus.proposeC[i] = make(chan string, 1)
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clus.confChangeC[i] = make(chan raftpb.ConfChange, 1)
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clus.commitC[i], clus.errorC[i] = newRaftNode(i+1, clus.peers, clus.proposeC[i], clus.confChangeC[i])
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clus.commitC[i], clus.errorC[i] = newRaftNode(i+1, clus.peers, false, clus.proposeC[i], clus.confChangeC[i])
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}
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return clus
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