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cluster_util.go
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cluster_util.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 (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"sort"
"time"
"github.com/coreos/etcd/Godeps/_workspace/src/github.com/coreos/go-semver/semver"
"github.com/coreos/etcd/pkg/types"
"github.com/coreos/etcd/version"
)
// isMemberBootstrapped tries to check if the given member has been bootstrapped
// in the given cluster.
func isMemberBootstrapped(cl *cluster, member string, rt http.RoundTripper, timeout time.Duration) bool {
rcl, err := getClusterFromRemotePeers(getRemotePeerURLs(cl, member), timeout, false, rt)
if err != nil {
return false
}
id := cl.MemberByName(member).ID
m := rcl.Member(id)
if m == nil {
return false
}
if len(m.ClientURLs) > 0 {
return true
}
return false
}
// GetClusterFromRemotePeers takes a set of URLs representing etcd peers, and
// attempts to construct a Cluster by accessing the members endpoint on one of
// these URLs. The first URL to provide a response is used. If no URLs provide
// a response, or a Cluster cannot be successfully created from a received
// response, an error is returned.
// Each request has a 10-second timeout. Because the upper limit of TTL is 5s,
// 10 second is enough for building connection and finishing request.
func GetClusterFromRemotePeers(urls []string, rt http.RoundTripper) (*cluster, error) {
return getClusterFromRemotePeers(urls, 10*time.Second, true, rt)
}
// If logerr is true, it prints out more error messages.
func getClusterFromRemotePeers(urls []string, timeout time.Duration, logerr bool, rt http.RoundTripper) (*cluster, error) {
cc := &http.Client{
Transport: rt,
Timeout: timeout,
}
for _, u := range urls {
resp, err := cc.Get(u + "/members")
if err != nil {
if logerr {
plog.Warningf("could not get cluster response from %s: %v", u, err)
}
continue
}
b, err := ioutil.ReadAll(resp.Body)
if err != nil {
if logerr {
plog.Warningf("could not read the body of cluster response: %v", err)
}
continue
}
var membs []*Member
if err = json.Unmarshal(b, &membs); err != nil {
if logerr {
plog.Warningf("could not unmarshal cluster response: %v", err)
}
continue
}
id, err := types.IDFromString(resp.Header.Get("X-Etcd-Cluster-ID"))
if err != nil {
if logerr {
plog.Warningf("could not parse the cluster ID from cluster res: %v", err)
}
continue
}
return newClusterFromMembers("", id, membs), nil
}
return nil, fmt.Errorf("could not retrieve cluster information from the given urls")
}
// getRemotePeerURLs returns peer urls of remote members in the cluster. The
// returned list is sorted in ascending lexicographical order.
func getRemotePeerURLs(cl Cluster, local string) []string {
us := make([]string, 0)
for _, m := range cl.Members() {
if m.Name == local {
continue
}
us = append(us, m.PeerURLs...)
}
sort.Strings(us)
return us
}
// getVersions returns the versions of the members in the given cluster.
// The key of the returned map is the member's ID. The value of the returned map
// is the semver versions string, including server and cluster.
// If it fails to get the version of a member, the key will be nil.
func getVersions(cl Cluster, local types.ID, rt http.RoundTripper) map[string]*version.Versions {
members := cl.Members()
vers := make(map[string]*version.Versions)
for _, m := range members {
if m.ID == local {
cv := "not_decided"
if cl.Version() != nil {
cv = cl.Version().String()
}
vers[m.ID.String()] = &version.Versions{Server: version.Version, Cluster: cv}
continue
}
ver, err := getVersion(m, rt)
if err != nil {
plog.Warningf("cannot get the version of member %s (%v)", m.ID, err)
vers[m.ID.String()] = nil
} else {
vers[m.ID.String()] = ver
}
}
return vers
}
// decideClusterVersion decides the cluster version based on the versions map.
// The returned version is the min server version in the map, or nil if the min
// version in unknown.
func decideClusterVersion(vers map[string]*version.Versions) *semver.Version {
var cv *semver.Version
lv := semver.Must(semver.NewVersion(version.Version))
for mid, ver := range vers {
if ver == nil {
return nil
}
v, err := semver.NewVersion(ver.Server)
if err != nil {
plog.Errorf("cannot understand the version of member %s (%v)", mid, err)
return nil
}
if lv.LessThan(*v) {
plog.Warningf("the local etcd version %s is not up-to-date", lv.String())
plog.Warningf("member %s has a higher version %s", mid, ver.Server)
}
if cv == nil {
cv = v
} else if v.LessThan(*cv) {
cv = v
}
}
return cv
}
// isCompatibleWithCluster return true if the local member has a compatible version with
// the current running cluster.
// The version is considered as compatible when at least one of the other members in the cluster has a
// cluster version in the range of [MinClusterVersion, Version] and no known members has a cluster version
// out of the range.
// We set this rule since when the local member joins, another member might be offline.
func isCompatibleWithCluster(cl Cluster, local types.ID, rt http.RoundTripper) bool {
vers := getVersions(cl, local, rt)
minV := semver.Must(semver.NewVersion(version.MinClusterVersion))
maxV := semver.Must(semver.NewVersion(version.Version))
maxV = &semver.Version{
Major: maxV.Major,
Minor: maxV.Minor,
}
return isCompatibleWithVers(vers, local, minV, maxV)
}
func isCompatibleWithVers(vers map[string]*version.Versions, local types.ID, minV, maxV *semver.Version) bool {
var ok bool
for id, v := range vers {
// ignore comparison with local version
if id == local.String() {
continue
}
if v == nil {
continue
}
clusterv, err := semver.NewVersion(v.Cluster)
if err != nil {
plog.Errorf("cannot understand the cluster version of member %s (%v)", id, err)
continue
}
if clusterv.LessThan(*minV) {
plog.Warningf("the running cluster version(%v) is lower than the minimal cluster version(%v) supported", clusterv.String(), minV.String())
return false
}
if maxV.LessThan(*clusterv) {
plog.Warningf("the running cluster version(%v) is higher than the maximum cluster version(%v) supported", clusterv.String(), maxV.String())
return false
}
ok = true
}
return ok
}
// getVersion returns the Versions of the given member via its
// peerURLs. Returns the last error if it fails to get the version.
func getVersion(m *Member, rt http.RoundTripper) (*version.Versions, error) {
cc := &http.Client{
Transport: rt,
}
var (
err error
resp *http.Response
)
for _, u := range m.PeerURLs {
resp, err = cc.Get(u + "/version")
if err != nil {
plog.Warningf("failed to reach the peerURL(%s) of member %s (%v)", u, m.ID, err)
continue
}
// etcd 2.0 does not have version endpoint on peer url.
if resp.StatusCode == http.StatusNotFound {
resp.Body.Close()
return &version.Versions{
Server: "2.0.0",
Cluster: "2.0.0",
}, nil
}
var b []byte
b, err = ioutil.ReadAll(resp.Body)
resp.Body.Close()
if err != nil {
plog.Warningf("failed to read out the response body from the peerURL(%s) of member %s (%v)", u, m.ID, err)
continue
}
var vers version.Versions
if err = json.Unmarshal(b, &vers); err != nil {
plog.Warningf("failed to unmarshal the response body got from the peerURL(%s) of member %s (%v)", u, m.ID, err)
continue
}
return &vers, nil
}
return nil, err
}
func MustDetectDowngrade(cv *semver.Version) {
lv := semver.Must(semver.NewVersion(version.Version))
// only keep major.minor version for comparison against cluster version
lv = &semver.Version{Major: lv.Major, Minor: lv.Minor}
if cv != nil && lv.LessThan(*cv) {
plog.Fatalf("cluster cannot be downgraded (current version: %s is lower than determined cluster version: %s).", version.Version, version.Cluster(cv.String()))
}
}