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cluster.go
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cluster.go
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// Copyright 2015 CoreOS, Inc.
//
// 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 etcdserver
import (
"bytes"
"crypto/sha1"
"encoding/binary"
"encoding/json"
"fmt"
"path"
"sort"
"strings"
"sync"
"github.com/coreos/etcd/pkg/netutil"
"github.com/coreos/etcd/pkg/types"
"github.com/coreos/etcd/raft"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/store"
"github.com/coreos/etcd/version"
"github.com/coreos/go-semver/semver"
)
const (
raftAttributesSuffix = "raftAttributes"
attributesSuffix = "attributes"
)
type Cluster interface {
// ID returns the cluster ID
ID() types.ID
// ClientURLs returns an aggregate set of all URLs on which this
// cluster is listening for client requests
ClientURLs() []string
// Members returns a slice of members sorted by their ID
Members() []*Member
// Member retrieves a particular member based on ID, or nil if the
// member does not exist in the cluster
Member(id types.ID) *Member
// IsIDRemoved checks whether the given ID has been removed from this
// cluster at some point in the past
IsIDRemoved(id types.ID) bool
// Version is the cluster-wide minimum major.minor version.
Version() *semver.Version
}
// Cluster is a list of Members that belong to the same raft cluster
type cluster struct {
id types.ID
token string
store store.Store
sync.Mutex // guards the fields below
version *semver.Version
members map[types.ID]*Member
// removed contains the ids of removed members in the cluster.
// removed id cannot be reused.
removed map[types.ID]bool
}
func newClusterFromURLsMap(token string, urlsmap types.URLsMap) (*cluster, error) {
c := newCluster(token)
for name, urls := range urlsmap {
m := NewMember(name, urls, token, nil)
if _, ok := c.members[m.ID]; ok {
return nil, fmt.Errorf("member exists with identical ID %v", m)
}
if uint64(m.ID) == raft.None {
return nil, fmt.Errorf("cannot use %x as member id", raft.None)
}
c.members[m.ID] = m
}
c.genID()
return c, nil
}
func newClusterFromMembers(token string, id types.ID, membs []*Member) *cluster {
c := newCluster(token)
c.id = id
for _, m := range membs {
c.members[m.ID] = m
}
return c
}
func newCluster(token string) *cluster {
return &cluster{
token: token,
members: make(map[types.ID]*Member),
removed: make(map[types.ID]bool),
}
}
func (c *cluster) ID() types.ID { return c.id }
func (c *cluster) Members() []*Member {
c.Lock()
defer c.Unlock()
var ms MembersByID
for _, m := range c.members {
ms = append(ms, m.Clone())
}
sort.Sort(ms)
return []*Member(ms)
}
func (c *cluster) Member(id types.ID) *Member {
c.Lock()
defer c.Unlock()
return c.members[id].Clone()
}
// MemberByName returns a Member with the given name if exists.
// If more than one member has the given name, it will panic.
func (c *cluster) MemberByName(name string) *Member {
c.Lock()
defer c.Unlock()
var memb *Member
for _, m := range c.members {
if m.Name == name {
if memb != nil {
plog.Panicf("two members with the given name %q exist", name)
}
memb = m
}
}
return memb.Clone()
}
func (c *cluster) MemberIDs() []types.ID {
c.Lock()
defer c.Unlock()
var ids []types.ID
for _, m := range c.members {
ids = append(ids, m.ID)
}
sort.Sort(types.IDSlice(ids))
return ids
}
func (c *cluster) IsIDRemoved(id types.ID) bool {
c.Lock()
defer c.Unlock()
return c.removed[id]
}
// PeerURLs returns a list of all peer addresses.
// The returned list is sorted in ascending lexicographical order.
func (c *cluster) PeerURLs() []string {
c.Lock()
defer c.Unlock()
urls := make([]string, 0)
for _, p := range c.members {
for _, addr := range p.PeerURLs {
urls = append(urls, addr)
}
}
sort.Strings(urls)
return urls
}
// ClientURLs returns a list of all client addresses.
// The returned list is sorted in ascending lexicographical order.
func (c *cluster) ClientURLs() []string {
c.Lock()
defer c.Unlock()
urls := make([]string, 0)
for _, p := range c.members {
for _, url := range p.ClientURLs {
urls = append(urls, url)
}
}
sort.Strings(urls)
return urls
}
func (c *cluster) String() string {
c.Lock()
defer c.Unlock()
b := &bytes.Buffer{}
fmt.Fprintf(b, "{ClusterID:%s ", c.id)
var ms []string
for _, m := range c.members {
ms = append(ms, fmt.Sprintf("%+v", m))
}
fmt.Fprintf(b, "Members:[%s] ", strings.Join(ms, " "))
var ids []string
for id := range c.removed {
ids = append(ids, fmt.Sprintf("%s", id))
}
fmt.Fprintf(b, "RemovedMemberIDs:[%s]}", strings.Join(ids, " "))
return b.String()
}
func (c *cluster) genID() {
mIDs := c.MemberIDs()
b := make([]byte, 8*len(mIDs))
for i, id := range mIDs {
binary.BigEndian.PutUint64(b[8*i:], uint64(id))
}
hash := sha1.Sum(b)
c.id = types.ID(binary.BigEndian.Uint64(hash[:8]))
}
func (c *cluster) SetID(id types.ID) { c.id = id }
func (c *cluster) SetStore(st store.Store) { c.store = st }
func (c *cluster) Recover() {
c.Lock()
defer c.Unlock()
c.members, c.removed = membersFromStore(c.store)
c.version = clusterVersionFromStore(c.store)
MustDetectDowngrade(c.version)
for _, m := range c.members {
plog.Infof("added member %s %v to cluster %s from store", m.ID, m.PeerURLs, c.id)
}
if c.version != nil {
plog.Infof("set the cluster version to %v from store", version.Cluster(c.version.String()))
}
}
// ValidateConfigurationChange takes a proposed ConfChange and
// ensures that it is still valid.
func (c *cluster) ValidateConfigurationChange(cc raftpb.ConfChange) error {
members, removed := membersFromStore(c.store)
id := types.ID(cc.NodeID)
if removed[id] {
return ErrIDRemoved
}
switch cc.Type {
case raftpb.ConfChangeAddNode:
if members[id] != nil {
return ErrIDExists
}
urls := make(map[string]bool)
for _, m := range members {
for _, u := range m.PeerURLs {
urls[u] = true
}
}
m := new(Member)
if err := json.Unmarshal(cc.Context, m); err != nil {
plog.Panicf("unmarshal member should never fail: %v", err)
}
for _, u := range m.PeerURLs {
if urls[u] {
return ErrPeerURLexists
}
}
case raftpb.ConfChangeRemoveNode:
if members[id] == nil {
return ErrIDNotFound
}
case raftpb.ConfChangeUpdateNode:
if members[id] == nil {
return ErrIDNotFound
}
urls := make(map[string]bool)
for _, m := range members {
if m.ID == id {
continue
}
for _, u := range m.PeerURLs {
urls[u] = true
}
}
m := new(Member)
if err := json.Unmarshal(cc.Context, m); err != nil {
plog.Panicf("unmarshal member should never fail: %v", err)
}
for _, u := range m.PeerURLs {
if urls[u] {
return ErrPeerURLexists
}
}
default:
plog.Panicf("ConfChange type should be either AddNode, RemoveNode or UpdateNode")
}
return nil
}
// AddMember adds a new Member into the cluster, and saves the given member's
// raftAttributes into the store. The given member should have empty attributes.
// A Member with a matching id must not exist.
func (c *cluster) AddMember(m *Member) {
c.Lock()
defer c.Unlock()
b, err := json.Marshal(m.RaftAttributes)
if err != nil {
plog.Panicf("marshal raftAttributes should never fail: %v", err)
}
p := path.Join(memberStoreKey(m.ID), raftAttributesSuffix)
if _, err := c.store.Create(p, false, string(b), false, store.TTLOptionSet{ExpireTime: store.Permanent}); err != nil {
plog.Panicf("create raftAttributes should never fail: %v", err)
}
c.members[m.ID] = m
}
// RemoveMember removes a member from the store.
// The given id MUST exist, or the function panics.
func (c *cluster) RemoveMember(id types.ID) {
c.Lock()
defer c.Unlock()
if _, err := c.store.Delete(memberStoreKey(id), true, true); err != nil {
plog.Panicf("delete member should never fail: %v", err)
}
delete(c.members, id)
if _, err := c.store.Create(removedMemberStoreKey(id), false, "", false, store.TTLOptionSet{ExpireTime: store.Permanent}); err != nil {
plog.Panicf("create removedMember should never fail: %v", err)
}
c.removed[id] = true
}
func (c *cluster) UpdateAttributes(id types.ID, attr Attributes) bool {
c.Lock()
defer c.Unlock()
if m, ok := c.members[id]; ok {
m.Attributes = attr
return true
}
_, ok := c.removed[id]
if ok {
plog.Warningf("skipped updating attributes of removed member %s", id)
} else {
plog.Panicf("error updating attributes of unknown member %s", id)
}
// TODO: update store in this function
return false
}
func (c *cluster) UpdateRaftAttributes(id types.ID, raftAttr RaftAttributes) {
c.Lock()
defer c.Unlock()
b, err := json.Marshal(raftAttr)
if err != nil {
plog.Panicf("marshal raftAttributes should never fail: %v", err)
}
p := path.Join(memberStoreKey(id), raftAttributesSuffix)
if _, err := c.store.Update(p, string(b), store.TTLOptionSet{ExpireTime: store.Permanent}); err != nil {
plog.Panicf("update raftAttributes should never fail: %v", err)
}
c.members[id].RaftAttributes = raftAttr
}
func (c *cluster) Version() *semver.Version {
c.Lock()
defer c.Unlock()
if c.version == nil {
return nil
}
return semver.Must(semver.NewVersion(c.version.String()))
}
func (c *cluster) SetVersion(ver *semver.Version) {
c.Lock()
defer c.Unlock()
if c.version != nil {
plog.Noticef("updated the cluster version from %v to %v", version.Cluster(c.version.String()), version.Cluster(ver.String()))
} else {
plog.Noticef("set the initial cluster version to %v", version.Cluster(ver.String()))
}
c.version = ver
MustDetectDowngrade(c.version)
}
func (c *cluster) isReadyToAddNewMember() bool {
nmembers := 1
nstarted := 0
for _, member := range c.members {
if member.IsStarted() {
nstarted++
}
nmembers++
}
if nstarted == 1 && nmembers == 2 {
// a case of adding a new node to 1-member cluster for restoring cluster data
// https://github.com/coreos/etcd/blob/master/Documentation/admin_guide.md#restoring-the-cluster
plog.Debugf("The number of started member is 1. This cluster can accept add member request.")
return true
}
nquorum := nmembers/2 + 1
if nstarted < nquorum {
plog.Warningf("Reject add member request: the number of started member (%d) will be less than the quorum number of the cluster (%d)", nstarted, nquorum)
return false
}
return true
}
func (c *cluster) isReadyToRemoveMember(id uint64) bool {
nmembers := 0
nstarted := 0
for _, member := range c.members {
if uint64(member.ID) == id {
continue
}
if member.IsStarted() {
nstarted++
}
nmembers++
}
nquorum := nmembers/2 + 1
if nstarted < nquorum {
plog.Warningf("Reject remove member request: the number of started member (%d) will be less than the quorum number of the cluster (%d)", nstarted, nquorum)
return false
}
return true
}
func membersFromStore(st store.Store) (map[types.ID]*Member, map[types.ID]bool) {
members := make(map[types.ID]*Member)
removed := make(map[types.ID]bool)
e, err := st.Get(storeMembersPrefix, true, true)
if err != nil {
if isKeyNotFound(err) {
return members, removed
}
plog.Panicf("get storeMembers should never fail: %v", err)
}
for _, n := range e.Node.Nodes {
var m *Member
m, err = nodeToMember(n)
if err != nil {
plog.Panicf("nodeToMember should never fail: %v", err)
}
members[m.ID] = m
}
e, err = st.Get(storeRemovedMembersPrefix, true, true)
if err != nil {
if isKeyNotFound(err) {
return members, removed
}
plog.Panicf("get storeRemovedMembers should never fail: %v", err)
}
for _, n := range e.Node.Nodes {
removed[mustParseMemberIDFromKey(n.Key)] = true
}
return members, removed
}
func clusterVersionFromStore(st store.Store) *semver.Version {
e, err := st.Get(path.Join(StoreClusterPrefix, "version"), false, false)
if err != nil {
if isKeyNotFound(err) {
return nil
}
plog.Panicf("unexpected error (%v) when getting cluster version from store", err)
}
return semver.Must(semver.NewVersion(*e.Node.Value))
}
// ValidateClusterAndAssignIDs validates the local cluster by matching the PeerURLs
// with the existing cluster. If the validation succeeds, it assigns the IDs
// from the existing cluster to the local cluster.
// If the validation fails, an error will be returned.
func ValidateClusterAndAssignIDs(local *cluster, existing *cluster) error {
ems := existing.Members()
lms := local.Members()
if len(ems) != len(lms) {
return fmt.Errorf("member count is unequal")
}
sort.Sort(MembersByPeerURLs(ems))
sort.Sort(MembersByPeerURLs(lms))
for i := range ems {
if !netutil.URLStringsEqual(ems[i].PeerURLs, lms[i].PeerURLs) {
return fmt.Errorf("unmatched member while checking PeerURLs")
}
lms[i].ID = ems[i].ID
}
local.members = make(map[types.ID]*Member)
for _, m := range lms {
local.members[m.ID] = m
}
return nil
}