Consul是一个支持多数据中心分布式高可用的服务发现和配置共享的服务软件，由HashiCorp公司用Go语言开发，基于Mozilla Public License 2.0的协议进行开源。Consul支持健康检查，并允许HTTP和DNS协议调用 API 存储键值对。
1 如何获取
目前最新版本是V0.6.4。
源码地址：
https://github.com/hashicorp/consul
可执行文件地址：
https://www.consul.io/downloads.html
MailList:
https://groups.google.com/group/consul-tool/
官方地址：
Consul by HashiCorp
官方演示：
http://demo.consul.io/ui/
2 搭建CONSUL环境
2.1 网络规划
|
主机名称 |
IP |
角色 |
数据中心 |
|
node0 |
192.168.192.120 |
Server |
DataCenter1 |
|
node1 |
192.168.192.121 |
Server |
DataCenter1 |
|
node2 |
192.168.192.122 |
Server |
DataCenter1 |
|
node3 |
192.168.192.123 |
Client |
DataCenter1 |
2.2 软件环境
CentOS：7.2.1511
Consul：V0.6.4
2.3 构建
1. 安装可执行文件consul
从上述所属地址中下载（linux类别X64）,然后执行
[ceph@node0 cousul]$sudo consul /usr/bin/ [ceph@node0 ~]# chmod755 consul查看是否安装成功
[ceph@node0 cousul]$consul version Consul v0.6.4 Consul Protocol: 3 (Understands back to: 1) [ceph@node0 cousul]$
查看帮助
[ceph@node0 consul]$consul --help usage: consul[--version] [--help] [
] Available commandsare: agent Runs a Consul agent configtest Validate config file event Fire a new event exec Executes a command on Consul nodes force-leave Forces a member of the cluster to enter the"left" state info Provides debugging information foroperators join Tell Consul agent to join cluster keygen Generates a new encryption key keyring Manages gossip layer encryption keys leave Gracefully leaves the Consul clusterand shuts down lock Execute a command holding a lock maint Controls node or service maintenancemode members Lists the members of a Consul cluster monitor Stream logs from a Consul agent reload Triggers the agent to reloadconfiguration files rtt Estimates network round trip timebetween nodes version Prints the Consul version watch Watch for changes in Consul
Consul有两种方式搭建方式：一是bootstrap模式，二是非bootstrap模式。
2.3.1 bootstrap模式
1. 在启动agent
在第一台节点上启动agent，以server模式运行，指定server角色的节点数目，指定节点名（在datacenter内节点名唯一），同时提供监听地址。
命令如下：
[ceph@node0 cousul]$ consul agent -server-bootstrap-expect=3 -data-dir=/tmp/consul -node=node0 -bind=192.168.192.120-dc=dc1 ==> WARNING: Expect Mode enabled,expecting 3 servers ==> Starting Consul agent... ==> Starting Consul agent RPC... ==> Consul agent running! Node name: 'node0' Datacenter: 'dc1' Server: true (bootstrap: false) Client Addr: 127.0.0.1 (HTTP: 8500,HTTPS: -1, DNS: 8600, RPC: 8400) Cluster Addr: 192.168.192.120 (LAN: 8301, WAN: 8302) Gossip encrypt: false, RPC-TLS: false, TLS-Incoming: false Atlas:
==> Log data will now stream inas it occurs: 2016/07/05 20:52:06 [INFO] serf: EventMemberJoin: node0 192.168.192.120 2016/07/05 20:52:06 [INFO] serf: EventMemberJoin: node0.dc1192.168.192.120 2016/07/05 20:52:06 [INFO] raft: Node at 192.168.192.120:8300 [Follower]entering Follower state 2016/07/05 20:52:06 [INFO] consul: adding LAN server node0 (Addr:192.168.192.120:8300) (DC: dc1) 2016/07/05 20:52:06 [INFO] consul: adding WAN server node0.dc1 (Addr:192.168.192.120:8300) (DC: dc1) 2016/07/05 20:52:06 [ERR] agent: failed to sync remote state: No clusterleader 2016/07/05 20:52:08 [WARN] raft: EnableSingleNode disabled, and no knownpeers. Aborting election.
之所以失败，原因在于当前的Datacenter没有 leader server
依次在另外两台机器部署agent作为server
节点node1
[ceph@node1 consul]$ consul agent-server -bootstrap-expect=3 -data-dir=/tmp/consul -node=node1-bind=192.168.192.121 -dc=dc1节点node2
[ceph@node2 consul]$ consul agent-server -bootstrap-expect=3 -data-dir=/tmp/consul -node=node2-bind=192.168.192.122 -dc=dc1目前，三个节点均不知道其他Server节点的存在，以node0为例
[ceph@node0 consul]$ consul members Node Address Status Type Build Protocol DC node0 192.168.192.120:8301 alive server 0.6.4 2 dc1 [ceph@node0 consul]$查看consul集群信息
[ceph@node0 consul]$ consul info agent: check_monitors= 0 check_ttls= 0 checks= 0 services= 1 build: prerelease= revision= 26a0ef8c version= 0.6.4 consul: bootstrap = false known_datacenters= 1 leader = false server = true ……当前节点为follow节点。
2. 触发选举leader
因为consul一般需要3~5个Server，因此，在节点node0上添加node1和node2。
[ceph@node0 consul]$ consul join192.168.192.121 Successfully joined cluster bycontacting 1 nodes. [ceph@node0 consul]$ consul join192.168.192.122 Successfully joined cluster bycontacting 1 nodes. [ceph@node0 consul]$ 观察三个节点consul日志：
Node0： 2016/07/05 21:10:55 [INFO] agent: (LAN) joining: [192.168.192.122] 2016/07/05 21:10:55 [INFO] serf: EventMemberJoin: node2 192.168.192.122 2016/07/05 21:10:55 [INFO] agent: (LAN) joined: 1 Err:
2016/07/05 21:10:55 [INFO] consul: adding LAN server node2 (Addr:192.168.192.122:8300) (DC: dc1) 2016/07/05 21:10:55 [INFO] consul: Attempting bootstrap with nodes:[192.168.192.120:8300 192.168.192.121:8300 192.168.192.122:8300] 2016/07/05 21:10:55 [INFO] consul: New leader elected: node2 2016/07/05 21:10:56 [INFO] agent: Synced service 'consul' Node1 2016/07/05 21:10:55 [INFO] serf:EventMemberJoin: node2 192.168.192.122 2016/07/05 21:10:55 [INFO] consul: adding LAN server node2 (Addr:192.168.192.122:8300) (DC: dc1) 2016/07/05 21:10:55 [INFO] consul: Attempting bootstrap with nodes:[192.168.192.121:8300 192.168.192.120:8300 192.168.192.122:8300] 2016/07/05 21:10:56 [INFO] consul: New leader elected: node2 2016/07/05 21:10:57 [INFO] agent:Synced service 'consul' Node2 2016/07/05 21:10:55 [INFO] serf: EventMemberJoin: node0 192.168.192.120 2016/07/05 21:10:55 [INFO] serf: EventMemberJoin: node1 192.168.192.121 2016/07/05 21:10:55 [INFO] consul: adding LAN server node0 (Addr:192.168.192.120:8300) (DC: dc1) 2016/07/05 21:10:55 [INFO]consul: Attempting bootstrap with nodes: [192.168.192.122:.168.192.120:8300 192.168.192.121:8300] 2016/07/05 21:10:55 [INFO] consul: adding LAN server node1 (Addr:192.168.192.121:8300) (DC: dc1) 2016/07/05 21:10:55 [WARN] raft: Heartbeat timeout reached, startingelection 2016/07/05 21:10:55 [INFO] raft: Node at 192.168.192.122:8300[Candidate] entering Candidate state 2016/07/05 21:10:55 [INFO] raft: Election won. Tally: 2 2016/07/05 21:10:55 [INFO] raft: Node at 192.168.192.122:8300 [Leader]entering Leader state 2016/07/05 21:10:55 [INFO] consul: cluster leadership acquired 2016/07/05 21:10:55 [INFO] consul: New leader elected: node2 2016/07/05 21:10:55 [INFO] raft: pipelining replication to peer192.168.192.121:8300 2016/07/05 21:10:55 [INFO] raft: pipelining replication to peer192.168.192.120:8300 2016/07/05 21:10:55 [INFO] consul: member 'node2' joined, marking healthalive 2016/07/05 21:10:55 [INFO] consul: member 'node0' joined, marking healthalive 2016/07/05 21:10:55 [INFO] consul: member 'node1' joined, marking healthalive 2016/07/05 21:10:58 [INFO] agent: Synced service 'consul'
由日志可知，举出了leadernode2
在node0查看members
[ceph@node0 consul]$ consul members Node Address Status Type Build Protocol DC node0 192.168.192.120:8301 alive server 0.6.4 2 dc1 node1 192.168.192.121:8301 alive server 0.6.4 2 dc1 node2 192.168.192.122:8301 alive server 0.6.4 2 dc1 [ceph@node0 consul]$查看info信息
[ceph@node0 consul]$ consul info agent: check_monitors= 0 check_ttls= 0 checks= 0 services= 1 build: prerelease= revision= 26a0ef8c version= 0.6.4 consul: bootstrap = false known_datacenters= 1 leader = false server = true ……节点node2上查看consul信息
[ceph@node2 consul]$ consul info agent: check_monitors= 0 check_ttls= 0 checks= 0 services= 1 build: prerelease= revision= 26a0ef8c version= 0.6.4 consul: bootstrap= false known_datacenters= 1 leader = true server = true3. 在node3上以client启动agent
[ceph@node3 consul]$ consul agent-data-dir=/tmp/consul -node=node3 -bind=192.168.192.123 -dc=dc1 ==> Starting Consul agent... ==> Starting Consul agent RPC... ==> Consul agent running! Node name: 'node3' Datacenter: 'dc1' Server: false (bootstrap: false) Client Addr: 127.0.0.1 (HTTP: 8500,HTTPS: -1, DNS: 8600, RPC: 8400) Cluster Addr: 192.168.192.123 (LAN: 8301, WAN: 8302) Gossip encrypt: false, RPC-TLS: false, TLS-Incoming: false Atlas:
==> Log data will now stream inas it occurs: 2016/07/05 21:21:02 [INFO] serf: EventMemberJoin: node3 192.168.192.123 2016/07/05 21:21:02 [ERR] agent: failed to sync remote state: No knownConsul servers
在节点node0上添加node3
[ceph@node0 consul]$ consul join192.168.192.123 Successfully joined cluster bycontacting 1 nodes. [ceph@node0 consul]$ consul members Node Address Status Type Build Protocol DC node0 192.168.192.120:8301 alive server 0.6.4 2 dc1 node1 192.168.192.121:8301 alive server 0.6.4 2 dc1 node2 192.168.192.122:8301 alive server 0.6.4 2 dc1 node3 192.168.192.123:8301 alive client 0.6.4 2 dc1 [ceph@node0 consul]$节点node3的日志如下：
2016/07/05 21:21:57 [INFO] serf: EventMemberJoin: node0 192.168.192.120 2016/07/05 21:21:57 [INFO] serf: EventMemberJoin: node2 192.168.192.122 2016/07/05 21:21:57 [INFO] serf: EventMemberJoin: node1 192.168.192.121 2016/07/05 21:21:57 [INFO] consul: adding server node0 (Addr:192.168.192.120:8300) (DC: dc1) 2016/07/05 21:21:57 [INFO] consul: adding server node2 (Addr:192.168.192.122:8300) (DC: dc1) 2016/07/05 21:21:57 [INFO] consul: adding server node1 (Addr:192.168.192.121:8300) (DC: dc1) 2016/07/05 21:21:57 [INFO] consul: New leader elected: node2 2016/07/05 21:21:57 [INFO] agent: Synced node info3. 依次关闭node3 node2：
Node0和node1的日志如下：
Node0 2016/07/05 21:24:00 [INFO] serf: EventMemberLeave: node2 192.168.192.122 2016/07/05 21:24:00 [INFO] consul: removing LAN server node2 (Addr:192.168.192.122:8300) (DC: dc1) 2016/07/05 21:24:00 [WARN] raft: Heartbeat timeout reached, startingelection 2016/07/05 21:24:00 [INFO] raft: Node at 192.168.192.120:8300[Candidate] entering Candidate state 2016/07/05 21:24:01 [INFO] raft: Duplicate RequestVote for same term: 2 2016/07/05 21:24:02 [WARN] raft: Election timeout reached, restartingelection 2016/07/05 21:24:02 [INFO] raft: Node at 192.168.192.120:8300[Candidate] entering Candidate state 2016/07/05 21:24:02 [INFO] raft: Election won. Tally: 2 2016/07/05 21:24:02 [INFO] raft: Node at 192.168.192.120:8300 [Leader]entering Leader state 2016/07/05 21:24:02 [INFO] consul: cluster leadership acquired 2016/07/05 21:24:02 [INFO] consul: New leader elected: node0 2016/07/05 21:24:02 [INFO] raft: pipelining replication to peer192.168.192.121:8300 2016/07/05 21:24:02 [INFO] consul: member 'node2' left, deregistering 2016/07/05 21:24:03 [INFO] agent.rpc: Accepted client: 127.0.0.1:35701 Node1 2016/07/05 21:24:00 [INFO] consul: removing LAN server node2 (Addr:192.168.192.122:8300) (DC: dc1) 2016/07/05 21:24:00 [WARN] raft: Rejecting vote request from192.168.192.120:8300 since we have a leader: 192.168.192.122:8300 2016/07/05 21:24:01 [WARN] raft: Heartbeat timeout reached, startingelection 2016/07/05 21:24:01 [INFO] raft: Node at 192.168.192.121:8300[Candidate] entering Candidate state 2016/07/05 21:24:02 [INFO] raft: Node at 192.168.192.121:8300 [Follower]entering Follower state 2016/07/05 21:24:02 [INFO]consul: New leader elected: node03 参考文献
[01]http://www.cnblogs.com/yatingyang/articles/4495098.html
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