第4节：Consul启动

启动Consul

安装配置好Consul以后，我们可以通过简单的命令启动consul。先来看最简单的启动方式：

consul agent -dev

在新终端中，执行如上操作。

hongweiyu@localhost:~$ consul agent -dev
==> Starting Consul agent...
==> Consul agent running!
           Version: 'v1.5.1'
           Node ID: '808644da-c526-efa2-4f37-fff96168dcd1'
         Node name: 'localhost'
        Datacenter: 'dc1' (Segment: '')
            Server: true (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, gRPC: 8502, DNS: 8600)
      Cluster Addr: 127.0.0.1 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false

==> Log data will now stream in as it occurs:

    2019/06/17 15:36:18 [DEBUG] agent: Using random ID "808644da-c526-efa2-4f37-fff96168dcd1" as node ID
    2019/06/17 15:36:18 [DEBUG] tlsutil: Update with version 1
    2019/06/17 15:36:18 [DEBUG] tlsutil: OutgoingRPCWrapper with version 1
    2019/06/17 15:36:18 [DEBUG] tlsutil: IncomingRPCConfig with version 1
    2019/06/17 15:36:18 [DEBUG] tlsutil: OutgoingRPCWrapper with version 1
    2019/06/17 15:36:18 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:808644da-c526-efa2-4f37-fff96168dcd1 Address:127.0.0.1:8300}]
    2019/06/17 15:36:18 [INFO] raft: Node at 127.0.0.1:8300 [Follower] entering Follower state (Leader: "")
    2019/06/17 15:36:18 [INFO] serf: EventMemberJoin: localhost.dc1 127.0.0.1
    2019/06/17 15:36:18 [INFO] serf: EventMemberJoin: localhost 127.0.0.1
    2019/06/17 15:36:18 [INFO] consul: Handled member-join event for server "localhost.dc1" in area "wan"
    2019/06/17 15:36:18 [INFO] consul: Adding LAN server localhost (Addr: tcp/127.0.0.1:8300) (DC: dc1)
    2019/06/17 15:36:18 [DEBUG] agent/proxy: managed Connect proxy manager started
    2019/06/17 15:36:18 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
    2019/06/17 15:36:18 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
    2019/06/17 15:36:18 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
    2019/06/17 15:36:18 [INFO] agent: started state syncer
    2019/06/17 15:36:18 [INFO] agent: Started gRPC server on 127.0.0.1:8502 (tcp)
    2019/06/17 15:36:18 [WARN] raft: Heartbeat timeout from "" reached, starting election
    2019/06/17 15:36:18 [INFO] raft: Node at 127.0.0.1:8300 [Candidate] entering Candidate state in term 2
    2019/06/17 15:36:18 [DEBUG] raft: Votes needed: 1
    2019/06/17 15:36:18 [DEBUG] raft: Vote granted from 808644da-c526-efa2-4f37-fff96168dcd1 in term 2. Tally: 1
    2019/06/17 15:36:18 [INFO] raft: Election won. Tally: 1
    2019/06/17 15:36:18 [INFO] raft: Node at 127.0.0.1:8300 [Leader] entering Leader state
    2019/06/17 15:36:18 [INFO] consul: cluster leadership acquired
    2019/06/17 15:36:18 [INFO] consul: New leader elected: localhost
    2019/06/17 15:36:18 [INFO] connect: initialized primary datacenter CA with provider "consul"
    2019/06/17 15:36:18 [DEBUG] consul: Skipping self join check for "localhost" since the cluster is too small
    2019/06/17 15:36:18 [INFO] consul: member 'localhost' joined, marking health alive
    2019/06/17 15:36:18 [DEBUG] agent: Skipping remote check "serfHealth" since it is managed automatically
    2019/06/17 15:36:18 [INFO] agent: Synced node info
    2019/06/17 15:36:18 [DEBUG] agent: Node info in sync
    2019/06/17 15:36:18 [DEBUG] agent: Skipping remote check "serfHealth" since it is managed automatically
    2019/06/17 15:36:18 [DEBUG] agent: Node info in sync
    2019/06/17 15:37:18 [DEBUG] consul: Skipping self join check for "localhost" since the cluster is too small
    2019/06/17 15:37:49 [DEBUG] agent: Skipping remote check "serfHealth" since it is managed automatically
    2019/06/17 15:37:49 [DEBUG] agent: Node info in sync
    2019/06/17 15:38:18 [DEBUG] manager: Rebalanced 1 servers, next active server is localhost.dc1 (Addr: tcp/127.0.0.1:8300) (DC: dc1)
    2019/06/17 15:38:18 [DEBUG] consul: Skipping self join check for "localhost" since the cluster is too small

上面贴出了Consul启动的输出日志，对日志做如下分析和说明：

• -dev：dev是consul多种启动模式的一种，dev是development的缩写，代表的是开发模式，该种启动模式仅仅是为了快速便捷的启动单节点consul，比如当前环境。
• Consul agent running!：表示该consul节点正常运行起来。
• Datacenter:’dc1′ 表示当前节点所属的数据中心的名称为dc1。
• Server：true（bootstrap：false） 表示该节点属于Server角色。Consul节点统称为agent，有两类：Client、Server。
• raft: Heartbeat timeout from "" reached, starting election Raft算法开始进行Leader节点选举。
• consul: cluster leadership acquired、consul: New leader elected: localhost Leader节点选举结束，本地唯一的节点被选举为leader节点。
• consul: member ‘localhost’ joined, marking health alive 目前localhost节点是一个健康正常的节点

查看consul节点信息

在consul启动后，可以通过命令查看节点的信息。在原有已经启动consul的终端窗口之外，重新开启新的终端窗口，执行如下命令：

consul members

Node       Address         Status  Type    Build  Protocol  DC   Segment
localhost  127.0.0.1:8301  alive   server  1.5.1  2         dc1  

输出日志说明：

• Address：节点地址
• Status：alive表示节点健康运行
• Type：节点的类型，有两种：server、client
• DC：Datacenter的缩写，dc1表示该节点属于Datacenter1

UI界面访问

终端命令行下启动consul的dev模式后，通过members命令查看节点信息，除此以外，还可以使用Http的浏览器访问的模式，查看节点信息。 consul启动，正常运行后，打开浏览器，在地址栏中键入：http://localhost:8500。可以查看节点信息，如下图 (opens new window)：

停止服务

在节点运行终端中执行：ctrl + c，表示退出节点运行。

2019/06/17 16:21:43 [INFO] agent: Caught signal:  interrupt
2019/06/17 16:21:43 [INFO] agent: Graceful shutdown disabled. Exiting
2019/06/17 16:21:43 [INFO] agent: Requesting shutdown
2019/06/17 16:21:43 [WARN] agent: dev mode disabled persistence, killing all proxies since we can't recover them
2019/06/17 16:21:43 [DEBUG] agent/proxy: Stopping managed Connect proxy manager
2019/06/17 16:21:43 [INFO] consul: shutting down server
2019/06/17 16:21:43 [WARN] serf: Shutdown without a Leave
2019/06/17 16:21:43 [WARN] serf: Shutdown without a Leave
2019/06/17 16:21:43 [INFO] manager: shutting down
2019/06/17 16:21:43 [INFO] agent: consul server down
2019/06/17 16:21:43 [INFO] agent: shutdown complete
2019/06/17 16:21:43 [INFO] agent: Stopping DNS server 127.0.0.1:8600 (tcp)
2019/06/17 16:21:43 [INFO] agent: Stopping DNS server 127.0.0.1:8600 (udp)
2019/06/17 16:21:43 [INFO] agent: Stopping HTTP server 127.0.0.1:8500 (tcp)
2019/06/17 16:21:43 [INFO] agent: Waiting for endpoints to shut down
2019/06/17 16:21:43 [INFO] agent: Endpoints down
2019/06/17 16:21:43 [INFO] agent: Exit code: 1

退出节点运行。

consul dev模式示意图

上诉consul agent -dev模式下的启动与运行consul节点。集群中只包含一个节点，唯一的节点被选举成为Leader节点。