配置管理新概念—Consul部署

我这里还是用了现有的4台centos的vmware的虚拟机做的测试。

Node Type

server1 server

server2 server

server2 server

agent1 agent

Consul 在CentOS上的安装

安装非常简单，安装完成后，就可以run Consul命令啦。

cd /usr/local/bin wget https://dl.bintray.com/mitchellh/consul/0.5.0_linux_amd64.zip unzip *.zip rm *.zip

consul命令行运行的方式非常简单，可以看到以下的参数，也可以参考consul的用户文档。

$ consul

usage: consul [--version] [--help] <command> [<args>]

Available commands are:

agent Runs a Consul agent

force-leave Forces a member of the cluster to enter the "left" state

info Provides debugging information for operators

join Tell Consul agent to join cluster

keygen Generates a new encryption key

leave Gracefully leaves the Consul cluster and shuts down

members Lists the members of a Consul cluster

monitor Stream logs from a Consul agent

reload Triggers the agent to reload configuration files

version Prints the Consul version

开启Bootstrap Server

一开始学习consul， 我们需要让consul 运行起来。consul server推荐至少在3~5个之间，推荐的方法是一开始启动其中一台server，并且配置到bootstrap的模式，该模式node可以指定自己作为leader，而不用进行选举。然后再依次启动其他server，配置为非bootstrap的模式。最后把第一个serverbootstrap模式停止，重新以非bootstrap模式启动，这样server之间就可以自动选举leader。

在上面的表中，我们需要指定server 1 做为bootstrap server，可以run下面的命令，以下是启动的过程。可以看到bootstrap模式下配置自己为leader。

[admin@localhost ~]$ consul agent -server -bootstrap -data-dir /tmp/consul

==> WARNING: Bootstrap mode enabled! Do not enable unless necessary

==> WARNING: It is highly recommended to set GOMAXPROCS higher than 1

==> Starting Consul agent...

==> Starting Consul agent RPC...

==> Consul agent running!

Node name: 'localhost.localdomain'

Datacenter: 'dc1'

Server: true (bootstrap: true)

Client Addr: 127.0.0.1 (HTTP: 8500, HTTPS: -1, DNS: 8600, RPC: 8400)

Cluster Addr: 10.74.15.87 (LAN: 8301, WAN: 8302)

Gossip encrypt: false, RPC-TLS: false, TLS-Incoming: false

Atlas: <disabled>

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

2015/05/11 02:58:06 [INFO] raft: Node at 10.74.15.87:8300 [Follower] entering Follower state

2015/05/11 02:58:06 [INFO] serf: EventMemberJoin: localhost.localdomain 10.74.15.87

2015/05/11 02:58:06 [INFO] serf: EventMemberJoin: localhost.localdomain.dc1 10.74.15.87

2015/05/11 02:58:06 [INFO] consul: adding server localhost.localdomain (Addr: 10.74.15.87:8300) (DC: dc1)

2015/05/11 02:58:06 [INFO] consul: adding server localhost.localdomain.dc1 (Addr: 10.74.15.87:8300) (DC: dc1)

2015/05/11 02:58:06 [ERR] agent: failed to sync remote state: No cluster leader

2015/05/11 02:58:08 [WARN] raft: Heartbeat timeout reached, starting election

2015/05/11 02:58:08 [INFO] raft: Node at 10.74.15.87:8300 [Candidate] entering Candidate state

2015/05/11 02:58:08 [INFO] raft: Election won. Tally: 1

2015/05/11 02:58:08 [INFO] raft: Node at 10.74.15.87:8300 [Leader] entering Leader state

2015/05/11 02:58:08 [INFO] consul: cluster leadership acquired

2015/05/11 02:58:08 [INFO] consul: New leader elected: localhost.localdomain

2015/05/11 02:58:08 [INFO] raft: Disabling EnableSingleNode (bootstrap)

2015/05/11 02:58:08 [INFO] consul: member 'localhost.localdomain' joined, marking health alive

2015/05/11 02:58:08 [INFO] agent: Synced service 'consul'

启动其他servers，在 server2 and server3, 我们用以下命令启动consul，不需要带bootstrap 选项。

[admin@localhost ~]$ consul agent -server -data-dir /tmp/consul

==> WARNING: It is highly recommended to set GOMAXPROCS higher than 1

==> Starting Consul agent...

==> Starting Consul agent RPC...

==> Consul agent running!

Node name: 'localhost.localdomain'

Datacenter: 'dc1'

Server: true (bootstrap: false)

Client Addr: 127.0.0.1 (HTTP: 8500, HTTPS: -1, DNS: 8600, RPC: 8400)

Cluster Addr: 10.74.15.87 (LAN: 8301, WAN: 8302)

Gossip encrypt: false, RPC-TLS: false, TLS-Incoming: false

Atlas: <disabled>

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

2015/05/11 03:01:54 [INFO] serf: EventMemberJoin: localhost.localdomain 10.74.15.87

2015/05/11 03:01:54 [INFO] serf: EventMemberJoin: localhost.localdomain.dc1 10.74.15.87

2015/05/11 03:01:54 [INFO] raft: Node at 10.74.15.87:8300 [Follower] entering Follower state

2015/05/11 03:01:54 [INFO] consul: adding server localhost.localdomain (Addr: 10.74.15.87:8300) (DC: dc1)

2015/05/11 03:01:54 [INFO] consul: adding server localhost.localdomain.dc1 (Addr: 10.74.15.87:8300) (DC: dc1)

2015/05/11 03:01:54 [ERR] agent: failed to sync remote state: No cluster leader

2015/05/11 03:01:55 [WARN] raft: EnableSingleNode disabled, and no known peers. Aborting election.

可以从log中看到，无法找到cluster leader和无法配置自己为leader，server2还没有和server1通信。这时，需要run下面的命令加入到server1的集群。

consul join 192.0.2.2 192.0.2.3

consul members //查看现有的cluster下面的node

当3台机子都加入到集群，我们需要配置这3台机子为同等的server，并且让它们自己选择leader，这时可以停止第一台的consul，然后再用以下命令启动：

consul agent -server -data-dir /tmp/consul

consul join 192.0.2.2 192.0.2.3

现在，3太机子会互相复制信息，或者可以处理某台机子挂掉后的情况。当有其他server需要加入时，重复上面的操作就可以。