1. 什么是Consul?
Consul 有很多组件，对于整体来说，它是一个服务发现和服务配置的工具，它提供了一下特性：
- 服务发现
- 健康检查
- KV存储
- 多数据中心
2.安装Consul
以下是在 CentOS 系统上操作
下载
wget https://releases.hashicorp.com/consul/1.1.0/consul_1.1.0_linux_amd64.zip查看版本
consul -v
Consul v1.1.0
Protocol 2 spoken by default, understands 2 to 3 (agent will automatically use protocol >2 when speaking to compatible agents)3.启动 Agent
使用dev模式启动。
$ consul agent -dev
==> Starting Consul agent...
==> Consul agent running!
Version: 'v1.1.0'
Node ID: 'a94cdf4f-e36d-9bef-927c-61c1d14500cd'
Node name: 'bogon'
Datacenter: 'dc1' (Segment: '<all>')
Server: true (Bootstrap: false)
Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, 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:
2018/06/23 00:03:45 [DEBUG] agent: Using random ID "a94cdf4f-e36d-9bef-927c-61c1d14500cd" as node ID
2018/06/23 00:03:45 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:a94cdf4f-e36d-9bef-927c-61c1d14500cd Address:127.0.0.1:8300}]
2018/06/23 00:03:45 [INFO] serf: EventMemberJoin: bogon.dc1 127.0.0.1
2018/06/23 00:03:45 [INFO] serf: EventMemberJoin: bogon 127.0.0.1
2018/06/23 00:03:45 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
2018/06/23 00:03:45 [INFO] raft: Node at 127.0.0.1:8300 [Follower] entering Follower state (Leader: "")
2018/06/23 00:03:45 [INFO] consul: Adding LAN server bogon (Addr: tcp/127.0.0.1:8300) (DC: dc1)
2018/06/23 00:03:45 [INFO] consul: Handled member-join event for server "bogon.dc1" in area "wan"
2018/06/23 00:03:45 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
2018/06/23 00:03:45 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
2018/06/23 00:03:45 [INFO] agent: started state syncer
2018/06/23 00:03:45 [WARN] raft: Heartbeat timeout from "" reached, starting election
2018/06/23 00:03:45 [INFO] raft: Node at 127.0.0.1:8300 [Candidate] entering Candidate state in term 2
2018/06/23 00:03:45 [DEBUG] raft: Votes needed: 1
2018/06/23 00:03:45 [DEBUG] raft: Vote granted from a94cdf4f-e36d-9bef-927c-61c1d14500cd in term 2. Tally: 1
2018/06/23 00:03:45 [INFO] raft: Election won. Tally: 1
2018/06/23 00:03:45 [INFO] raft: Node at 127.0.0.1:8300 [Leader] entering Leader state
2018/06/23 00:03:45 [INFO] consul: cluster leadership acquired
2018/06/23 00:03:45 [DEBUG] consul: Skipping self join check for "bogon" since the cluster is too small
2018/06/23 00:03:45 [INFO] consul: member 'bogon' joined, marking health alive
2018/06/23 00:03:45 [INFO] consul: New leader elected: bogon
2018/06/23 00:03:45 [DEBUG] agent: Skipping remote check "serfHealth" since it is managed automatically
2018/06/23 00:03:45 [INFO] agent: Synced node info
2018/06/23 00:03:46 [DEBUG] agent: Skipping remote check "serfHealth" since it is managed automatically
2018/06/23 00:03:46 [DEBUG] agent: Node info in sync
2018/06/23 00:03:46 [DEBUG] agent: Node info in sync4. 查看集群成员
在另外一个终端使用 consul members， 可以查看集群成员信息。
$ consul members
Node Address Status Type Build Protocol DC Segment
bogon 127.0.0.1:8301 alive server 1.1.0 2 dc1 <all>也可以通过HTTP API 来查看Consul成员信息
$ curl localhost:8500/v1/catalog/nodes
[
{
"ID": "a94cdf4f-e36d-9bef-927c-61c1d14500cd",
"Node": "bogon",
"Address": "127.0.0.1",
"Datacenter": "dc1",
"TaggedAddresses": {
"lan": "127.0.0.1",
"wan": "127.0.0.1"
},
"Meta": {
"consul-network-segment": ""
},
"CreateIndex": 5,
"ModifyIndex": 6
}
]5.服务注册
定义一个服务步骤
$ sudo mkdir /etc/consul.d定义一个服务名为web, 运行端口为80
$ echo '{"service": {"name": "web", "tags": ["rails"], "port": 80}}' \
| sudo tee /etc/consul.d/web.json重启agent,并制定配置目录
$ consul agent -dev -config-dir=/etc/consul.d
==> Starting Consul agent...
...
[INFO] agent: Synced service 'web'
...下面通过HTTP API的方式来查询服务
$ curl http://localhost:8500/v1/catalog/service/web
[
{
"ID": "68530a9c-2434-9a80-32ac-e4e455086655",
"Node": "bogon",
"Address": "127.0.0.1",
"Datacenter": "dc1",
"TaggedAddresses": {
"lan": "127.0.0.1",
"wan": "127.0.0.1"
},
"NodeMeta": {
"consul-network-segment": ""
},
"ServiceID": "web",
"ServiceName": "web",
"ServiceTags": [
"rails"
],
"ServiceAddress": "",
"ServiceMeta": {},
"ServicePort": 80,
"ServiceEnableTagOverride": false,
"CreateIndex": 6,
"ModifyIndex": 6
}
]同时也可以通过下面的HTTP API 来查询服务的健康状况
$ curl 'http://localhost:8500/v1/health/service/web?passing'
[
{
"Node": {
"ID": "68530a9c-2434-9a80-32ac-e4e455086655",
"Node": "bogon",
"Address": "127.0.0.1",
"Datacenter": "dc1",
"TaggedAddresses": {
"lan": "127.0.0.1",
"wan": "127.0.0.1"
},
"Meta": {
"consul-network-segment": ""
},
"CreateIndex": 5,
"ModifyIndex": 6
},
"Service": {
"ID": "web",
"Service": "web",
"Tags": [
"rails"
],
"Address": "",
"Meta": null,
"Port": 80,
"EnableTagOverride": false,
"CreateIndex": 6,
"ModifyIndex": 6
},
"Checks": [
{
"Node": "bogon",
"CheckID": "serfHealth",
"Name": "Serf Health Status",
"Status": "passing",
"Notes": "",
"Output": "Agent alive and reachable",
"ServiceID": "",
"ServiceName": "",
"ServiceTags": [],
"Definition": {},
"CreateIndex": 5,
"ModifyIndex": 5
}
]
}
]更新服务
可以通过修改配置文件和发送SIGHUP 到agent， 更新服务的信息。
另外，也可以通过HTTP API 的方式动态添加或者移除服务信息。