Consul - 服务注册和健康检查

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服务注册

定义一个服务

  1. 为Consul配置创建一个目录/etc/consul.d。Consul装载配置目录中所有的配置文件。[root@Automation bin]# sudo mkdir /etc/consul.d
  2. 我们将创建一个服务定义配置文件。echo '{"service": {"name": "web", "tags": ["rails"], "port": 80}}'>/etc/consul.d/web.json
  3. 用配置目录对数重启代理：
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    [root@Automation bin]# curl http://10.24.33.75:8500/v1/catalog/service/web
    curl: (7) couldn't connect to host
    [root@Automation bin]# consul agent -dev -config-dir /etc/consul.d
    ==> Starting Consul agent...
    ==> Consul agent running!
               Version: 'v1.0.2'
               Node ID: '8f55dc0e-5765-5941-e566-5a4f1166645f'
             Node name: 'Automation'
            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:

        2017/12/25 15:46:02 [DEBUG] Using random ID "8f55dc0e-5765-5941-e566-5a4f1166645f" as node ID
        2017/12/25 15:46:02 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:8f55dc0e-5765-5941-e566-5a4f1166645f Address:127.0.0.1:8300}]
        2017/12/25 15:46:02 [INFO] raft: Node at 127.0.0.1:8300 [Follower] entering Follower state (Leader: "")
        2017/12/25 15:46:02 [INFO] serf: EventMemberJoin: Automation.dc1 127.0.0.1
        2017/12/25 15:46:02 [INFO] serf: EventMemberJoin: Automation 127.0.0.1
        2017/12/25 15:46:02 [INFO] consul: Adding LAN server Automation (Addr: tcp/127.0.0.1:8300) (DC: dc1)
        2017/12/25 15:46:02 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
        2017/12/25 15:46:02 [INFO] consul: Handled member-join event for server "Automation.dc1" in area "wan"
        2017/12/25 15:46:02 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
        2017/12/25 15:46:02 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
        2017/12/25 15:46:02 [INFO] agent: started state syncer
        2017/12/25 15:46:02 [WARN] raft: Heartbeat timeout from "" reached, starting election
        2017/12/25 15:46:02 [INFO] raft: Node at 127.0.0.1:8300 [Candidate] entering Candidate state in term 2
        2017/12/25 15:46:02 [DEBUG] raft: Votes needed: 1
        2017/12/25 15:46:02 [DEBUG] raft: Vote granted from 8f55dc0e-5765-5941-e566-5a4f1166645f in term 2. Tally: 1
        2017/12/25 15:46:02 [INFO] raft: Election won. Tally: 1
        2017/12/25 15:46:02 [INFO] raft: Node at 127.0.0.1:8300 [Leader] entering Leader state
        2017/12/25 15:46:02 [INFO] consul: cluster leadership acquired
        2017/12/25 15:46:02 [DEBUG] consul: Skipping self join check for "Automation" since the cluster is too small
        2017/12/25 15:46:02 [INFO] consul: member 'Automation' joined, marking health alive
        2017/12/25 15:46:02 [INFO] consul: New leader elected: Automation
        2017/12/25 15:46:02 [DEBUG] Skipping remote check "serfHealth" since it is managed automatically
        2017/12/25 15:46:02 [INFO] agent: Synced service "web"

你会注意到在输出中”synced service ‘web’”。这意味着代理已经从配置文件中装载了该服务定义，并且已经成功注册该服务到服务目录中。

如果你想注册多个服务，你可以在Consul配置目录中创建多个服务定义文件。

查询服务

这里只试了HTTP API：

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[root@Automation ~]# curl http://localhost:8500/v1/catalog/service/web
[
    {
        "ID": "8f55dc0e-5765-5941-e566-5a4f1166645f",
        "Node": "Automation",
        "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": "",
        "ServicePort": 80,
        "ServiceEnableTagOverride": false,
        "CreateIndex": 6,
        "ModifyIndex": 6
    }
]

健康检查

定义检查

定义check的位置为/etc/consul.d/，格式跟定义服务一样，也是JSON。
下边我们定义两个check，分别为ping.json和web.json。内容如下：

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{
    "check": {
        "name": "ping",
        "script": "ping -c1 google.com >/dev/null",
        "interval": "30s"
    }
}

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{
    "service": {
        "name": "web",
        "tags": [
            "springCloud"
        ],
        "port": 80,
        "check": {
            "script": "curl localhost >/dev/null 2>&1",
            "interval": "10s"
        }
    }
}

第一个定义增加了一个主机级别的检测，名为”ping”。每隔30秒检查一次。在一个基于脚本的健康检测中，该检测使用启动Consul进程的用户来启动该检测。如果检测命令返回一个非0的返回码，那么该节点将被标记为不健康。
第二个命令修改名为web的服务，增加了一个检测，每隔10秒执行一次。

检查健康状态

修改后，需要重启一下代理

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[root@Automation consul.d]# consul agent -dev -config-dir /etc/consul.d
==> Starting Consul agent...
==> Error starting agent: Failed to register service "web": Scripts are disabled on this agent; to enable, configure 'enable_script_checks' to true
[root@Automation consul.d]# consul agent -dev -enable-script-checks -config-dir /etc/consul.d
==> Starting Consul agent...
==> Consul agent running!
           Version: 'v1.0.2'
           Node ID: '33b66ccd-d48f-283d-c9ec-94f2f677c1af'
         Node name: 'Automation'
        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:

    2017/12/25 16:16:34 [DEBUG] Using random ID "33b66ccd-d48f-283d-c9ec-94f2f677c1af" as node ID
    2017/12/25 16:16:34 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:33b66ccd-d48f-283d-c9ec-94f2f677c1af Address:127.0.0.1:8300}]
    2017/12/25 16:16:34 [INFO] raft: Node at 127.0.0.1:8300 [Follower] entering Follower state (Leader: "")
    2017/12/25 16:16:34 [INFO] serf: EventMemberJoin: Automation.dc1 127.0.0.1
    2017/12/25 16:16:34 [INFO] serf: EventMemberJoin: Automation 127.0.0.1
    2017/12/25 16:16:34 [WARN] agent: check "service:web" has the 'script' field, which has been deprecated and replaced with the 'args' field. See https://www.consul.io/docs/agent/checks.html
    2017/12/25 16:16:34 [WARN] agent: check "ping" has the 'script' field, which has been deprecated and replaced with the 'args' field. See https://www.consul.io/docs/agent/checks.html
    2017/12/25 16:16:34 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp)
    2017/12/25 16:16:34 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp)
    2017/12/25 16:16:34 [INFO] consul: Adding LAN server Automation (Addr: tcp/127.0.0.1:8300) (DC: dc1)
    2017/12/25 16:16:34 [INFO] consul: Handled member-join event for server "Automation.dc1" in area "wan"
    2017/12/25 16:16:34 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp)
    2017/12/25 16:16:34 [INFO] agent: started state syncer
    2017/12/25 16:16:34 [WARN] raft: Heartbeat timeout from "" reached, starting election
    2017/12/25 16:16:34 [INFO] raft: Node at 127.0.0.1:8300 [Candidate] entering Candidate state in term 2
    2017/12/25 16:16:34 [DEBUG] raft: Votes needed: 1
    2017/12/25 16:16:34 [DEBUG] raft: Vote granted from 33b66ccd-d48f-283d-c9ec-94f2f677c1af in term 2. Tally: 1
    2017/12/25 16:16:34 [INFO] raft: Election won. Tally: 1
    2017/12/25 16:16:34 [INFO] raft: Node at 127.0.0.1:8300 [Leader] entering Leader state
    2017/12/25 16:16:34 [INFO] consul: cluster leadership acquired
    2017/12/25 16:16:34 [INFO] consul: New leader elected: Automation
    2017/12/25 16:16:34 [DEBUG] consul: Skipping self join check for "Automation" since the cluster is too small
    2017/12/25 16:16:34 [INFO] consul: member 'Automation' joined, marking health alive
    2017/12/25 16:16:34 [DEBUG] Skipping remote check "serfHealth" since it is managed automatically
    2017/12/25 16:16:34 [INFO] agent: Synced service "web"
    2017/12/25 16:16:34 [DEBUG] agent: Check "service:web" in sync
    2017/12/25 16:16:34 [INFO] agent: Synced check "ping"

检查：

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[root@Automation ~]# curl http://localhost:8500/v1/health/state/critical
[
    {
        "Node": "Automation",
        "CheckID": "ping",
        "Name": "ping",
        "Status": "critical",
        "Notes": "",
        "Output": "",
        "ServiceID": "",
        "ServiceName": "",
        "ServiceTags": [],
        "Definition": {},
        "CreateIndex": 7,
        "ModifyIndex": 7
    }
]
You have new mail in /var/spool/mail/root
[root@Automation ~]# curl http://localhost:8500/v1/health/state/critical
[]

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