环境
centos:7.3
docker:1.12.6
kernel:3.10.0-514.6.1.el7.x86_64
consul:0.8.1
server1:10.1.13.221
server2:10.1.13.222

consul的功能
·服务发现
·健康检查
·支持多数据中心
·key/value存储
consul的使用场景
·docker实例的注册与配置共享
·coreos实例的注册与配置共享
consul的优势
·使用 Raft 算法来保证一致性, 比复杂的 Paxos 算法更直接. 相比较而言, zookeeper 采用的是 Paxos, 而 etcd 使用的则是 Raft
·支持多数据中心，内外网的服务采用不同的端口进行监听。 多数据中心集群可以避免单数据中心的单点故障,而其部署则需要考虑网络延迟, 分片等情况等. zookeeper 和 etcd 均不提供多数据中心功能的支持
·支持健康检查. etcd 不提供此功能
·官方提供web管理界面, etcd 无此功能
·支持 http 和 dns 协议接口. zookeeper 的集成较为复杂, etcd 只支持 http 协议
consul发现机制
当一个Consul代理启动后，它并不知道其它节点的存在，它是一个孤立的 单节点集群，如果想感知到其它节点的存在，它必须加入到一个现存的集群，要加入到一个现存的集群，它只用加入集群中任意一个现存的成员，当加入一个现存的成员后，会通过成员间的通讯很快发现集群中的其它成员，一个Consul代理可以加入任意一个代理，而不仅仅是服务节点

参数
-advertise：通知展现地址用来改变我们给集群中的其他节点展现的地址，一般情况下-bind地址就是展现地址
-bootstrap：用来控制一个server是否在bootstrap模式，在一个datacenter中只能有一个server处于bootstrap模式，当一个server处于bootstrap模式时，可以自己选举为raft leader。
-bootstrap-expect：在一个datacenter中期望提供的server节点数目，当该值提供的时候，consul一直等到达到指定sever数目的时候才会引导整个集群，该标记不能和bootstrap公用
-bind：该地址用来在集群内部的通讯，集群内的所有节点到地址都必须是可达的，默认是0.0.0.0
-client：consul绑定在哪个client地址上，这个地址提供HTTP、DNS、RPC等服务，默认是127.0.0.1
-config-file：明确的指定要加载哪个配置文件
-config-dir：配置文件目录，里面所有以.json结尾的文件都会被加载
-data-dir：提供一个目录用来存放agent的状态，所有的agent允许都需要该目录，该目录必须是稳定的，系统重启后都继续存在
-dc：该标记控制agent允许的datacenter的名称，默认是dc1
-encrypt：指定secret key，使consul在通讯时进行加密，key可以通过consul keygen生成，同一个集群中的节点必须使用相同的key
-join：加入一个已经启动的agent的ip地址，可以多次指定多个agent的地址。如果consul不能加入任何指定的地址中，则agent会启动失败，默认agent启动时不会加入任何节点。
-retry-join：和join类似，但是允许你在第一次失败后进行尝试。
-retry-interval：两次join之间的时间间隔，默认是30s
-retry-max：尝试重复join的次数，默认是0，也就是无限次尝试
-log-level：consul agent启动后显示的日志信息级别。默认是info，可选：trace、debug、info、warn、err。
-node：节点在集群中的名称，在一个集群中必须是唯一的，默认是该节点的主机名
-protocol：consul使用的协议版本
-rejoin：使consul忽略先前的离开，在再次启动后仍旧尝试加入集群中。
-server：定义agent运行在server模式，每个集群至少有一个server，建议每个集群的server不要超过5个
-syslog：开启系统日志功能，只在linux/osx上生效
-pid-file:提供一个路径来存放pid文件，可以使用该文件进行SIGINT/SIGHUP(关闭/更新)agent

下载地址：
https://releases.hashicorp.com/consul/0.8.1/consul_0.8.1_linux_amd64.zip

安装：
#unzip consul_0.8.1_linux_amd64.zip
#mv consul /usr/local/bin

简单使用

 

[root@localhost ~]# nohup consul agent -server -bootstrap -data-dir /opt/consul -node=s221 -bind=10.1.13.221 & 
[root@localhost ~]# consul info
agent:
        check_monitors = 0
        check_ttls = 0
        checks = 0
        services = 1
build:
        prerelease = 
        revision = 'e9ca44d
        version = 0.8.1
consul:
        bootstrap = true
        known_datacenters = 1
        leader = true
        leader_addr = 10.1.13.221:8300
        server = true
raft:
        applied_index = 191
        commit_index = 191
        fsm_pending = 0
        last_contact = 0
        last_log_index = 191
        last_log_term = 4
        last_snapshot_index = 0
        last_snapshot_term = 0
        latest_configuration = [{Suffrage:Voter ID:10.1.13.221:8300 Address:10.1.13.221:8300}]
        latest_configuration_index = 1
        num_peers = 0
        protocol_version = 2
        protocol_version_max = 3
        protocol_version_min = 0
        snapshot_version_max = 1
        snapshot_version_min = 0
        state = Leader
        term = 4
runtime:
        arch = amd64
        cpu_count = 2
        goroutines = 63
        max_procs = 2
        os = linux
        version = go1.8.1
serf_lan:
        encrypted = false
        event_queue = 1
        event_time = 3
        failed = 0
        health_score = 0
        intent_queue = 0
        left = 0
        member_time = 1
        members = 1
        query_queue = 0
        query_time = 1
serf_wan:
        encrypted = false
        event_queue = 0
        event_time = 1
        failed = 0
        health_score = 0
        intent_queue = 0
        left = 0
        member_time = 1
        members = 1
        query_queue = 0
        query_time = 1

server2:10.1.13.222[client端]
[root@localhost ~]# nohup consul agent -data-dir /opt/consul -node=c222 -bind=10.1.13.222 &

这时查看状态，是没有加入到server端的
[root@localhost ~]# consul members
Node  Address           Status  Type    Build  Protocol  DC
c222  10.1.13.222:8301  alive   client  0.8.1  2         dc1

需要在server1:10.1.13.221服务端执行，join后边加客户端的ip
[root@localhost ~]# consul join 10.1.13.222

或者在client启动的时候加入
[root@localhost ~]# nohup consul agent -data-dir /opt/consul -node=c222 -join=10.1.13.221 -bind=10.1.13.222 &

再查看状态，服务端和客户端都一样
[root@localhost ~]# consul members
Node  Address           Status  Type    Build  Protocol  DC
c222  10.1.13.222:8301  alive   client  0.8.1  2         dc1
s221  10.1.13.221:8301  alive   server  0.8.1  2         dc1

DNS查看
[root@localhost ~]# dig @127.0.0.1 -p 8600 c222.node.consul
...
c222.node.consul.       0       IN      A       10.1.13.222
...

服务注册
服务注册有两种方式
·服务定义:是服务注册最常用的方法
·HTTP API:通过HTTP API方式注册

服务定义注册
服务定义
[root@localhost ~]# mkdir /etc/consul.d
[root@localhost ~]# echo '{"service": {"name": "web", "tags": ["rails"], "port": 80}}' >/etc/consul.d/web.json
[root@localhost ~]# nohup consul agent -server -bootstrap-expect 1 -data-dir /opt/consul -config-dir /etc/consul.d -node=s221 -bind=10.1.13.221 &

查看定义的服务
方式1
[root@localhost ~]# dig @127.0.0.1 -p8600 web.service.consul
...
web.service.consul.     0       IN      A       10.1.13.221
...

方式2
[root@lcoalhost ~]# curl -s http://localhost:8500/v1/catalog/service/web | python -m json.tool
[
    {
        "Address": "10.1.13.221",
        "CreateIndex": 325,
        "ID": "cea73f23-8839-eef8-c932-2ab960e7e019",
        "ModifyIndex": 325,
        "Node": "s221",
        "NodeMeta": {},
        "ServiceAddress": "",
        "ServiceEnableTagOverride": false,
        "ServiceID": "web",
        "ServiceName": "web",
        "ServicePort": 80,
        "ServiceTags": [
            "rails"
        ],
        "TaggedAddresses": {
            "lan": "10.1.13.221",
            "wan": "10.1.13.221"
        }
    }
]

HTTP API方式注册

服务定义
[root@lcoalhost ~]# curl -X PUT http://127.0.0.1:8500/v1/agent/service/register -i -H "Content-Type:application/json" -H "Accept:application/json" -d '{"ID":"db","Name" :"db","Tags":["duxuefeng"],"Address":"10.1.13.221","Port":3306}'

查看定义的服务
[root@localhost ~]# curl -s http://localhost:8500/v1/catalog/service/db | python -m json.tool    
[
    {
        "Address": "10.1.13.221",
        "CreateIndex": 377,
        "ID": "cea73f23-8839-eef8-c932-2ab960e7e019",
        "ModifyIndex": 377,
        "Node": "s221",
        "NodeMeta": {},
        "ServiceAddress": "10.1.13.221",
        "ServiceEnableTagOverride": false,
        "ServiceID": "db",
        "ServiceName": "db",
        "ServicePort": 3306,
        "ServiceTags": [
            "duxuefeng"
        ],
        "TaggedAddresses": {
            "lan": "10.1.13.221",
            "wan": "10.1.13.221"
        }
    }
]

服务添加主机
如果在server1上注册一个服务
server1:10.1.13.221[server端]
[root@lcoaolhost ~]# curl -X PUT http://127.0.0.1:8500/v1/agent/service/register -i -H "Content-Type:application/json" -H "Accept:application/json" -d '{"ID":"nginx","Name" :"nginx","Tags":["duxuefeng"],"Address":"10.1.13.221","Port":80}'

需要在其他主机上（server2）添加自己到服务中，前提是这台主机已经加入到cluster中
server2:10.1.13.222[client端]
[root@localhost ~]# consul members
Node  Address           Status  Type    Build  Protocol  DC
c222  10.1.13.222:8301  alive   client  0.8.1  2         dc1
s221  10.1.13.221:8301  alive   server  0.8.1  2         dc1

[root@localhost ~]# curl -X PUT http://127.0.0.1:8500/v1/agent/service/register -i -H "Content-Type:application/json" -H "Accept:application/json" -d '{"ID":"nginx","Name" :"nginx","Tags":["duxuefeng"],"Address":"10.1.13.222","Port":80}'

查看
[root@localhost ~]# curl -s http://localhost:8500/v1/catalog/service/db | python -m json.tool   
[
    {
        "Address": "10.1.13.222",
        "CreateIndex": 506,
        "ID": "8b53f13a-f95b-b23a-db14-a4bc62e83bea",
        "ModifyIndex": 506,
        "Node": "c222",
        "NodeMeta": {},
        "ServiceAddress": "10.1.13.222",
        "ServiceEnableTagOverride": false,
        "ServiceID": "nginx",
        "ServiceName": "nginx",
        "ServicePort": 80,
        "ServiceTags": [
            "duxuefeng"
        ],
        "TaggedAddresses": {
            "lan": "10.1.13.222",
            "wan": "10.1.13.222"
        }
    },
    {
        "Address": "10.1.13.221",
        "CreateIndex": 377,
        "ID": "cea73f23-8839-eef8-c932-2ab960e7e019",
        "ModifyIndex": 503,
        "Node": "s221",
        "NodeMeta": {},
        "ServiceAddress": "10.1.13.221",
        "ServiceEnableTagOverride": false,
        "ServiceID": "nginx",
        "ServiceName": "nginx",
        "ServicePort": 80,
        "ServiceTags": [
            "duxuefeng"
        ],
        "TaggedAddresses": {
            "lan": "10.1.13.221",
            "wan": "10.1.13.221"
        }
    }
]

删除节点
在要删除的节点上退出consul cluster
server2:10.1.13.222[client端]
[root@localhost ~]# consul leave

[root@localhost ~]# curl -s http://localhost:8500/v1/catalog/service/db | python -m json.tool   
[
    {
        "Address": "10.1.13.221",
        "CreateIndex": 377,
        "ID": "cea73f23-8839-eef8-c932-2ab960e7e019",
        "ModifyIndex": 503,
        "Node": "s221",
        "NodeMeta": {},
        "ServiceAddress": "10.1.13.221",
        "ServiceEnableTagOverride": false,
        "ServiceID": "db",
        "ServiceName": "db",
        "ServicePort": 3306,
        "ServiceTags": [
            "duxuefeng"
        ],
        "TaggedAddresses": {
            "lan": "10.1.13.221",
            "wan": "10.1.13.221"
        }
    }
]

consul节点健康检查
在需要做健康检查的节点上，应放在所有节点上
[root@localhost ~]# echo '{"check": {"name": "ping", "script": "ping -c1 www.baidu.com >/dev/null", "interval": "30s"}}' >/etc/consul.d/ping.json
[root@localhost ~]# nohup consul agent -data-dir /opt/consul -node=c222 -join=10.1.13.221 -bind=10.1.13.222 -config-dir /etc/consul.d &

[root@localhost ~]# curl -s http://localhost:8500/v1/health/state/any | python -m json.tool 
[
    {
        "CheckID": "ping",
        "CreateIndex": 621,
        "ModifyIndex": 625,
        "Name": "ping",
        "Node": "c222",
        "Notes": "",
        "Output": "",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    },
    {
        "CheckID": "serfHealth",
        "CreateIndex": 622,
        "ModifyIndex": 622,
        "Name": "Serf Health Status",
        "Node": "c222",
        "Notes": "",
        "Output": "Agent alive and reachable",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    },
    {
        "CheckID": "ping",
        "CreateIndex": 600,
        "ModifyIndex": 603,
        "Name": "ping",
        "Node": "s221",
        "Notes": "",
        "Output": "",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    },
    {
        "CheckID": "serfHealth",
        "CreateIndex": 175,
        "ModifyIndex": 175,
        "Name": "Serf Health Status",
        "Node": "s221",
        "Notes": "",
        "Output": "Agent alive and reachable",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    }
]

测试

把本机的解析关掉
[root@localhost ~]# vi /etc/resolv.conf 
# Generated by NetworkManager
search 223.5.5.5
#nameserver 8.8.8.8
#nameserver 10.1.1.1

[root@localhost ~]# curl -s http://localhost:8500/v1/health/state/any | python -m json.tool 
[
    {
        "CheckID": "ping",
        "CreateIndex": 621,
        "ModifyIndex": 652,
        "Name": "ping",
        "Node": "c222",
        "Notes": "",
        "Output": "ping: www.baidu.com: \u672a\u77e5\u7684\u540d\u79f0\u6216\u670d\u52a1\n",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "critical"
    },
    {
        "CheckID": "serfHealth",
        "CreateIndex": 622,
        "ModifyIndex": 622,
        "Name": "Serf Health Status",
        "Node": "c222",
        "Notes": "",
        "Output": "Agent alive and reachable",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    },
    {
        "CheckID": "ping",
        "CreateIndex": 600,
        "ModifyIndex": 603,
        "Name": "ping",
        "Node": "s221",
        "Notes": "",
        "Output": "",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    },
    {
        "CheckID": "serfHealth",
        "CreateIndex": 175,
        "ModifyIndex": 175,
        "Name": "Serf Health Status",
        "Node": "s221",
        "Notes": "",
        "Output": "Agent alive and reachable",
        "ServiceID": "",
        "ServiceName": "",
        "Status": "passing"
    }
]

服务检查
echo '{"service": {"name": "web", "tags": ["rails"], "port": 80, "check": {"script": "curl localhost:80 >/dev/null 2>&1", "interval": "10s"}}}' >/etc/consul.d/web.json

[root@localhost ~]# nohup consul agent -data-dir /opt/consul -node=c222 -join=10.1.13.221 -bind=10.1.13.222 -config-dir /etc/consul.d &

K/V data

定义值
[root@localhost ~]# curl -X PUT -d 'test' http://127.0.0.1:8500/v1/kv/web/key1
[root@localhost ~]# curl -X PUT -d 'test' http://127.0.0.1:8500/v1/kv/web/key2?flags=42
[root@localhost ~]# curl -X PUT -d 'test' http://127.0.0.1:8500/v1/kv/web/web/sub/key3
查看
[root@localhost ~]# curl -s http://127.0.0.1:8500/v1/kv/?recurse|python -m json.tool
[
    {
        "CreateIndex": 734,
        "Flags": 0,
        "Key": "web/key1",
        "LockIndex": 0,
        "ModifyIndex": 745,
        "Value": "dGVzdA=="
    },
    {
        "CreateIndex": 749,
        "Flags": 42,
        "Key": "web/key2",
        "LockIndex": 0,
        "ModifyIndex": 749,
        "Value": "dGVzdA=="
    },
    {
        "CreateIndex": 751,
        "Flags": 0,
        "Key": "web/web/sub/key3",
        "LockIndex": 0,
        "ModifyIndex": 751,
        "Value": "dGVzdA=="
    }
]

删除key
[root@localhost ~]# curl -s http://127.0.0.1:8500/v1/kv/web/key1|python -m json.tool

修改key
curl -X PUT -d 'newval' http://127.0.0.1:8500/v1/kv/web/key1?cas=734
curl -s http://127.0.0.1:8500/v1/kv/web/key1|python -m json.tool

web UI

[root@localhost ~]# wget https://releases.hashicorp.com/consul/0.8.1/consul_0.8.1_web_ui.zip
[root@localhost ~]# unzip consul_0.8.1_web_ui.zip
[root@localhost ~]# mv static consul-ui
[root@localhost ~]# mv  consul-ui /opt
[root@localhost ~]# nohup consul agent -server -bootstrap-expect 1 -data-dir /opt/consul -config-dir /etc/consul.d -node=s221 -bind=10.1.13.221 -ui-dir /opt/consul/consul-ui &

启动后访问http://ip:8500/ui