Created
November 15, 2017 05:05
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Sample hashicorp/raft + hashicorp/serf app
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package main | |
import ( | |
"crypto/md5" | |
"flag" | |
"fmt" | |
"io" | |
"log" | |
"os" | |
"path/filepath" | |
"strconv" | |
"strings" | |
"time" | |
"github.com/hashicorp/memberlist" | |
"github.com/hashicorp/raft" | |
"github.com/hashicorp/raft-boltdb" | |
"github.com/hashicorp/serf/serf" | |
) | |
var ( | |
members string | |
serfPort int | |
) | |
func init() { | |
flag.StringVar(&members, "members", "", "127.0.0.1:1111,127.0.0.1:2222") | |
flag.IntVar(&serfPort, "serfPort", 0, "1111") | |
} | |
func main() { | |
flag.Parse() | |
var peers []string | |
if members != "" { | |
peers = strings.Split(members, ",") | |
} | |
ip, err := GetFirstPrivateIP() | |
if err != nil { | |
log.Fatal(err) | |
} | |
serfEvents := make(chan serf.Event, 16) | |
memberlistConfig := memberlist.DefaultLANConfig() | |
memberlistConfig.BindAddr = ip | |
memberlistConfig.BindPort = serfPort | |
memberlistConfig.LogOutput = os.Stdout | |
serfConfig := serf.DefaultConfig() | |
serfConfig.NodeName = fmt.Sprintf("%s:%d", ip, serfPort) | |
serfConfig.EventCh = serfEvents | |
serfConfig.MemberlistConfig = memberlistConfig | |
serfConfig.LogOutput = os.Stdout | |
s, err := serf.Create(serfConfig) | |
if err != nil { | |
log.Fatal(err) | |
} | |
// Join an existing cluster by specifying at least one known member. | |
if len(peers) > 0 { | |
_, err = s.Join(peers, false) | |
if err != nil { | |
log.Fatal(err) | |
} | |
} | |
workDir, err := os.Getwd() | |
if err != nil { | |
log.Fatal(err) | |
} | |
raftPort := serfPort + 1 | |
id := fmt.Sprintf("%x", md5.Sum([]byte(fmt.Sprintf("%s:%d", ip, raftPort)))) | |
dataDir := filepath.Join(workDir, id) | |
err = os.RemoveAll(dataDir + "/") | |
if err != nil { | |
log.Fatal(err) | |
} | |
err = os.MkdirAll(dataDir, 0777) | |
if err != nil { | |
log.Fatal(err) | |
} | |
raftDBPath := filepath.Join(dataDir, "raft.db") | |
raftDB, err := raftboltdb.NewBoltStore(raftDBPath) | |
if err != nil { | |
log.Fatal(err) | |
} | |
snapshotStore, err := raft.NewFileSnapshotStore(dataDir, 1, os.Stdout) | |
if err != nil { | |
log.Fatal(err) | |
} | |
raftAddr := ip + ":" + strconv.Itoa(raftPort) | |
trans, err := raft.NewTCPTransport(raftAddr, nil, 3, 10*time.Second, os.Stdout) | |
if err != nil { | |
log.Fatal(err) | |
} | |
c := raft.DefaultConfig() | |
c.LogOutput = os.Stdout | |
c.LocalID = raft.ServerID(raftAddr) | |
r, err := raft.NewRaft(c, &fsm{}, raftDB, raftDB, snapshotStore, trans) | |
if err != nil { | |
log.Fatal(err) | |
} | |
bootstrapConfig := raft.Configuration{ | |
Servers: []raft.Server{ | |
{ | |
Suffrage: raft.Voter, | |
ID: raft.ServerID(raftAddr), | |
Address: raft.ServerAddress(raftAddr), | |
}, | |
}, | |
} | |
// Add known peers to bootstrap | |
for _, node := range peers { | |
if node == raftAddr { | |
continue | |
} | |
bootstrapConfig.Servers = append(bootstrapConfig.Servers, raft.Server{ | |
Suffrage: raft.Voter, | |
ID: raft.ServerID(node), | |
Address: raft.ServerAddress(node), | |
}) | |
} | |
f := r.BootstrapCluster(bootstrapConfig) | |
if err := f.Error(); err != nil { | |
log.Fatalf("error bootstrapping: %s", err) | |
} | |
ticker := time.NewTicker(3 * time.Second) | |
for { | |
select { | |
case <-ticker.C: | |
future := r.VerifyLeader() | |
fmt.Printf("Showing peers known by %s:\n", raftAddr) | |
if err = future.Error(); err != nil { | |
fmt.Println("Node is a follower") | |
} else { | |
fmt.Println("Node is leader") | |
} | |
cfuture := r.GetConfiguration() | |
if err = cfuture.Error(); err != nil { | |
log.Fatalf("error getting config: %s", err) | |
} | |
configuration := cfuture.Configuration() | |
for _, server := range configuration.Servers { | |
fmt.Println(server.Address) | |
} | |
case ev := <-serfEvents: | |
leader := r.VerifyLeader() | |
if memberEvent, ok := ev.(serf.MemberEvent); ok { | |
for _, member := range memberEvent.Members { | |
changedPeer := member.Addr.String() + ":" + strconv.Itoa(int(member.Port+1)) | |
if memberEvent.EventType() == serf.EventMemberJoin { | |
if leader.Error() == nil { | |
f := r.AddVoter(raft.ServerID(changedPeer), raft.ServerAddress(changedPeer), 0, 0) | |
if f.Error() != nil { | |
log.Fatalf("error adding voter: %s", err) | |
} | |
} | |
} else if memberEvent.EventType() == serf.EventMemberLeave || memberEvent.EventType() == serf.EventMemberFailed || memberEvent.EventType() == serf.EventMemberReap { | |
if leader.Error() == nil { | |
f := r.RemoveServer(raft.ServerID(changedPeer), 0, 0) | |
if f.Error() != nil { | |
log.Fatalf("error removing server: %s", err) | |
} | |
} | |
} | |
} | |
} | |
} | |
} | |
} | |
type fsm struct { | |
} | |
func (f *fsm) Apply(*raft.Log) interface{} { | |
return nil | |
} | |
func (f *fsm) Snapshot() (raft.FSMSnapshot, error) { | |
return nil, nil | |
} | |
func (f *fsm) Restore(io.ReadCloser) error { | |
return nil | |
} |
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I don't think it is possible with the library. See discussion here: hashicorp/raft#151