Consul介绍
Consul是HashiCorp公司推出的开源工具[开源地址：https://github.com/hashicorp/consul]，用于实现分布式系统的服务发现与配置。
与市面上其他系统比较如下：
总体而言， Consul用Golang实现，因此具有天然可移植性（支持Linux、windows和Mac OS X）；安装包仅包含一个可执行文件，方便部署，与Docker等轻量级容器可无缝配合。
此外，关于Consul的架构以及相关的角色，如下图所示：
以Server模式运行的Consul Agent节点用于维护Consul集群的状态，官方建议每个Consul Cluster至少有3个或以上的运行在Server Mode的Agent，Client节点不限。Consul支持多数据中心，每个数据中心的Consul Cluster都会在运行于Server模式下的Agent节点中选出一个Leader节点，这个选举过程通过Consul实现的raft协议保证，多个 Server节点上的Consul数据信息是强一致的。处于Client Mode的Consul Agent节点比较简单，无状态，仅仅负责将请求转发给Server Agent节点。
集群搭建
笔者打算通过五台Centos7来搭建Consul集群，借助VMware Workstation搭建，当然，最主要的是这台虚拟主机一定要相互ping通，最好关闭防火墙，而且，虚拟机也需要和宿主机（实比如笔者的Windows10操作系统）ping通，具体问题和配置可搜索一下，图片如下：
其中130作为leader角色，129和131作为follower角色，当然，在实际环境中，leader的角色不一定是固定的，会随着环境变化而变化（比如网络断了、宕机了等等）这个我们后续来验证。132和133作为客户端，并安装NET Core 2.1环境，再次提示，一定要保证在这个环境中的所有系统相互之间均能Ping通。
step1：关闭防火墙
systemctl stop firewalld systemctl disable firewalld
step2：安装consul
wget https://releases.hashicorp.com/consul/1.3.0/consul_1.3.0_linux_amd64.zip unzip consul_1.3.0_linux_amd64.zip
step3：节点1
./consul agent -server -ui -bootstrap-expect=3 -data-dir=/tmp/consul -node=consul-1 -client=0.0.0.0 -bind=192.168.153.129 -datacenter=dc1 #设置129为服务器
bootstrap_expect > 0: expecting 3 servers
==> Starting Consul agent...
==> Consul agent running!
Version: 'v1.3.0'
Node ID: 'c612a043-8906-d6e1-8f4b-ef1c8afb371b'
Node name: 'consul-1'
Datacenter: 'dc1' (Segment: '<all>')
Server: true (Bootstrap: false)
Client Addr: [0.0.0.0] (HTTP: 8500, HTTPS: -1, gRPC: -1, DNS: 8600)
Cluster Addr: 192.168.153.129 (LAN: 8301, WAN: 8302)
Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false
==> Log data will now stream in as it occurs:
2018/10/15 04:53:30 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb3777 Address:192.168.153.131:8300} {Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb371a Address:192.168.153.130:8300} {Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb371b Address:192.168.153.129:8300}]
2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-1.dc1 192.168.153.129
2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-1 192.168.153.129
2018/10/15 04:53:30 [WARN] agent: Service name "LZZ.DEV.ClientService" will not be discoverable via DNS due to invalid characters. Valid characters include all alpha-numerics and dashes.
2018/10/15 04:53:30 [WARN] agent: Service name "LZZ.PRO.ClientService" will not be discoverable via DNS due to invalid characters. Valid characters include all alpha-numerics and dashes.
2018/10/15 04:53:30 [WARN] agent: check 'service:17947fbe-24ee-40e1-8e49-ea42415ada23' has deregister interval below minimum of 1m0s
2018/10/15 04:53:30 [WARN] agent: check 'service:81d5b247-73d1-4ae5-9d1a-208770ca4e6a' has deregister interval below minimum of 1m0s
2018/10/15 04:53:30 [INFO] agent: Started DNS server 0.0.0.0:8600 (udp)
2018/10/15 04:53:30 [INFO] raft: Node at 192.168.153.129:8300 [Follower] entering Follower state (Leader: "")
2018/10/15 04:53:30 [INFO] serf: Attempting re-join to previously known node: consul-3.dc1: 192.168.153.131:8302
2018/10/15 04:53:30 [INFO] serf: Attempting re-join to previously known node: LZZ.PRODUCTS.WebServer: 192.168.153.133:8301
2018/10/15 04:53:30 [INFO] consul: Adding LAN server consul-1 (Addr: tcp/192.168.153.129:8300) (DC: dc1)
2018/10/15 04:53:30 [INFO] consul: Raft data found, disabling bootstrap mode
2018/10/15 04:53:30 [INFO] consul: Handled member-join event for server "consul-1.dc1" in area "wan"
2018/10/15 04:53:30 [WARN] agent/proxy: running as root, will not start managed proxies
2018/10/15 04:53:30 [INFO] agent: Started DNS server 0.0.0.0:8600 (tcp)
2018/10/15 04:53:30 [INFO] agent: Started HTTP server on [::]:8500 (tcp)
2018/10/15 04:53:30 [INFO] agent: started state syncer
2018/10/15 04:53:30 [INFO] serf: Attempting re-join to previously known node: consul-3: 192.168.153.131:8301
2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-3.dc1 192.168.153.131
2018/10/15 04:53:30 [WARN] memberlist: Refuting an alive message
2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-2.dc1 192.168.153.130
2018/10/15 04:53:30 [INFO] serf: Re-joined to previously known node: consul-3.dc1: 192.168.153.131:8302
2018/10/15 04:53:30 [INFO] consul: Handled member-join event for server "consul-3.dc1" in area "wan"
2018/10/15 04:53:30 [INFO] consul: Handled member-join event for server "consul-2.dc1" in area "wan"
2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-3 192.168.153.131
2018/10/15 04:53:30 [WARN] memberlist: Refuting a suspect message (from: consul-1)
2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-2 192.168.153.130
2018/10/15 04:53:30 [INFO] serf: Re-joined to previously known node: consul-3: 192.168.153.131:8301
2018/10/15 04:53:30 [INFO] consul: Adding LAN server consul-3 (Addr: tcp/192.168.153.131:8300) (DC: dc1)
2018/10/15 04:53:30 [INFO] consul: Adding LAN server consul-2 (Addr: tcp/192.168.153.130:8300) (DC: dc1)
Client Addr的地址是[0.0.0.0]，代表本机上的所有IPv4地址。集群地址是：192.168.153.129。稍后我们介绍命令一些主要参数的的作用。
step4：节点2
./consul agent -server -ui -bootstrap-expect=3 -data-dir=/tmp/consul -node=consul-2 -client=0.0.0.0 -bind=192.168.153.130 -datacenter=dc1 -join 192.168.153.129 # join 加入到129中
bootstrap_expect > 0: expecting 3 servers
==> Starting Consul agent...
==> Joining cluster...
Join completed. Synced with 1 initial agents
==> Consul agent running!
Version: 'v1.3.0'
Node ID: 'c612a043-8906-d6e1-8f4b-ef1c8afb371a'
Node name: 'consul-2'
Datacenter: 'dc1' (Segment: '<all>')
Server: true (Bootstrap: false)
Client Addr: [0.0.0.0] (HTTP: 8500, HTTPS: -1, gRPC: -1, DNS: 8600)
Cluster Addr: 192.168.153.130 (LAN: 8301, WAN: 8302)
Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false
==> Log data will now stream in as it occurs:
2018/10/15 04:56:36 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb3777 Address:192.168.153.131:8300} {Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb371a Address:192.168.153.130:8300} {Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb371b Address:192.168.153.129:8300}]
2018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-2.dc1 192.168.153.130
2018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-2 192.168.153.130
2018/10/15 04:56:36 [INFO] raft: Node at 192.168.153.130:8300 [Follower] entering Follower state (Leader: "")
2018/10/15 04:56:36 [INFO] serf: Attempting re-join to previously known node: consul-3.dc1: 192.168.153.131:8302
2018/10/15 04:56:36 [INFO] serf: Attempting re-join to previously known node: consul-3: 192.168.153.131:8301
2018/10/15 04:56:36 [INFO] consul: Adding LAN server consul-2 (Addr: tcp/192.168.153.130:8300) (DC: dc1)
2018/10/15 04:56:36 [INFO] consul: Raft data found, disabling bootstrap mode
2018/10/15 04:56:36 [INFO] consul: Handled member-join event for server "consul-2.dc1" in area "wan"
2018/10/15 04:56:36 [WARN] memberlist: Refuting a suspect message (from: consul-2)
2018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-1 192.168.153.129
2018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-3 192.168.153.131
2018/10/15 04:56:36 [INFO] serf: Re-joined to previously known node: consul-3: 192.168.153.131:8301
2018/10/15 04:56:36 [INFO] consul: Adding LAN server consul-1 (Addr: tcp/192.168.153.129:8300) (DC: dc1)
2018/10/15 04:56:36 [INFO] consul: Adding LAN server consul-3 (Addr: tcp/192.168.153.131:8300) (DC: dc1)
2018/10/15 04:56:36 [WARN] memberlist: Refuting a suspect message (from: consul-2.dc1)
2018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-1.dc1 192.168.153.129
2018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-3.dc1 192.168.153.131
2018/10/15 04:56:36 [INFO] serf: Re-joined to previously known node: consul-3.dc1: 192.168.153.131:8302
2018/10/15 04:56:36 [INFO] consul: Handled member-join event for server "consul-1.dc1" in area "wan"
2018/10/15 04:56:36 [INFO] consul: Handled member-join event for server "consul-3.dc1" in area "wan"
2018/10/15 04:56:36 [INFO] agent: Started DNS server 0.0.0.0:8600 (udp)
2018/10/15 04:56:36 [WARN] agent/proxy: running as root, will not start managed proxies
2018/10/15 04:56:36 [INFO] agent: Started DNS server 0.0.0.0:8600 (tcp)
2018/10/15 04:56:36 [INFO] agent: Started HTTP server on [::]:8500 (tcp)
2018/10/15 04:56:36 [INFO] agent: (LAN) joining: [192.168.153.129]
2018/10/15 04:56:36 [INFO] agent: (LAN) joined: 1 Err: <nil>
2018/10/15 04:56:36 [INFO] agent: started state syncer
step5：节点3
./consul agent -server -ui -bootstrap-expect=3 -data-dir=/tmp/consul -node=consul-3 -client=0.0.0.0 -bind=192.168.153.131 -datacenter=dc1 -join 192.168.153.129
bootstrap_expect > 0: expecting 3 servers
==> Starting Consul agent...
==> Joining cluster...
Join completed. Synced with 1 initial agents
==> Consul agent running!
Version: 'v1.3.0'
Node ID: 'c612a043-8906-d6e1-8f4b-ef1c8afb3777'
Node name: 'consul-3'
Datacenter: 'dc1' (Segment: '<all>')
Server: true (Bootstrap: false)
Client Addr: [0.0.0.0] (HTTP: 8500, HTTPS: -1, gRPC: -1, DNS: 8600)
Cluster Addr: 192.168.153.131 (LAN: 8301, WAN: 8302)
Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false
==> Log data will now stream in as it occurs:
2018/10/15 05:01:15 [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb3777 Address:192.168.153.131:8300} {Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb371b Address:192.168.153.129:8300} {Suffrage:Voter ID:c612a043-8906-d6e1-8f4b-ef1c8afb371a Address:192.168.153.130:8300}]
2018/10/15 05:01:15 [INFO] raft: Node at 192.168.153.131:8300 [Follower] entering Follower state (Leader: "")
2018/10/15 05:01:15 [INFO] serf: EventMemberJoin: consul-3.dc1 192.168.153.131
2018/10/15 05:01:15 [INFO] serf: EventMemberJoin: consul-3 192.168.153.131
2018/10/15 05:01:15 [INFO] serf: Attempting re-join to previously known node: consul-1.dc1: 192.168.153.129:8302
2018/10/15 05:01:15 [INFO] serf: Attempting re-join to previously known node: consul-1: 192.168.153.129:8301
2018/10/15 05:01:15 [INFO] consul: Adding LAN server consul-3 (Addr: tcp/192.168.153.131:8300) (DC: dc1)
2018/10/15 05:01:15 [INFO] consul: Raft data found, disabling bootstrap mode
2018/10/15 05:01:15 [INFO] consul: Handled member-join event for server "consul-3.dc1" in area "wan"
2018/10/15 05:01:15 [WARN] agent/proxy: running as root, will not start managed proxies
2018/10/15 05:01:15 [INFO] agent: Started DNS server 0.0.0.0:8600 (udp)
2018/10/15 05:01:15 [INFO] agent: Started DNS server 0.0.0.0:8600 (tcp)
2018/10/15 05:01:15 [INFO] agent: Started HTTP server on [::]:8500 (tcp)
2018/10/15 05:01:15 [INFO] agent: (LAN) joining: [192.168.153.129]
2018/10/15 05:01:15 [INFO] serf: EventMemberJoin: consul-1 192.168.153.129
2018/10/15 05:01:15 [INFO] serf: Re-joined to previously known node: consul-1: 192.168.153.129:8301
2018/10/15 05:01:15 [INFO] consul: Adding LAN server consul-1 (Addr: tcp/192.168.153.129:8300) (DC: dc1)
2018/10/15 05:01:15 [INFO] serf: EventMemberJoin: consul-1.dc1 192.168.153.129
2018/10/15 05:01:15 [INFO] serf: Re-joined to previously known node: consul-1.dc1: 192.168.153.129:8302
2018/10/15 05:01:15 [INFO] consul: Handled member-join event for server "consul-1.dc1" in area "wan"
2018/10/15 05:01:15 [INFO] agent: (LAN) joined: 1 Err: <nil>
2018/10/15 05:01:15 [INFO] agent: started state syncer
step6：客户端1
./consul agent -bind 192.168.153.132 -client 192.168.153.132 -data-dir=/tmp/consul -node LZZ.DEV.WebServer -join 192.168.153.129
==> Starting Consul agent...
==> Joining cluster...
Join completed. Synced with 1 initial agents
==> Consul agent running!
Version: 'v1.3.0'
Node ID: 'c7125043-8906-d6e1-8f4b-ef1c8afb371b'
Node name: 'LZZ.DEV.WebServer'
Datacenter: 'dc1' (Segment: '')
Server: false (Bootstrap: false)
Client Addr: [192.168.153.132] (HTTP: 8500, HTTPS: -1, gRPC: -1, DNS: 8600)
Cluster Addr: 192.168.153.132 (LAN: 8301, WAN: 8302)
Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false
==> Log data will now stream in as it occurs:
2018/10/15 05:03:15 [WARN] agent: Node name "LZZ.DEV.WebServer" will not be discoverable via DNS due to invalid characters. Valid characters include all alpha-numerics and dashes.
2018/10/15 05:03:15 [INFO] serf: EventMemberJoin: LZZ.DEV.WebServer 192.168.153.132
2018/10/15 05:03:15 [INFO] agent: Started DNS server 192.168.153.132:8600 (udp)
2018/10/15 05:03:15 [WARN] agent/proxy: running as root, will not start managed proxies
2018/10/15 05:03:15 [INFO] agent: Started DNS server 192.168.153.132:8600 (tcp)
2018/10/15 05:03:15 [INFO] agent: Started HTTP server on 192.168.153.132:8500 (tcp)
2018/10/15 05:03:15 [INFO] agent: (LAN) joining: [192.168.153.129]
2018/10/15 05:03:15 [INFO] serf: EventMemberJoin: consul-1 192.168.153.129
2018/10/15 05:03:15 [INFO] serf: EventMemberJoin: consul-3 192.168.153.131
2018/10/15 05:03:15 [INFO] agent: (LAN) joined: 1 Err: <nil>
2018/10/15 05:03:15 [INFO] agent: started state syncer
2018/10/15 05:03:15 [INFO] consul: adding server consul-1 (Addr: tcp/192.168.153.129:8300) (DC: dc1)
2018/10/15 05:03:15 [INFO] consul: adding server consul-3 (Addr: tcp/192.168.153.131:8300) (DC: dc1)
2018/10/15 05:03:15 [INFO] agent: Synced node info
step6：客户端2
./consul agent -bind 192.168.153.133 -client 192.168.153.133 -data-dir=/tmp/consul -node LZZ.PRO.WebServer -join 192.168.153.129
==> Starting Consul agent...
==> Joining cluster...
Join completed. Synced with 1 initial agents
==> Consul agent running!
Version: 'v1.3.0'
Node ID: '1aa2a043-8906-d6e1-8f4b-ef1c8afb371b'
Node name: 'LZZ.PRO.WebServer'
Datacenter: 'dc1' (Segment: '')
Server: false (Bootstrap: false)
Client Addr: [192.168.153.133] (HTTP: 8500, HTTPS: -1, gRPC: -1, DNS: 8600)
Cluster Addr: 192.168.153.133 (LAN: 8301, WAN: 8302)
Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false
==> Log data will now stream in as it occurs:
2018/10/15 05:04:26 [WARN] agent: Node name "LZZ.PRO.WebServer" will not be discoverable via DNS due to invalid characters. Valid characters include all alpha-numerics and dashes.
2018/10/15 05:04:26 [INFO] serf: EventMemberJoin: LZZ.PRO.WebServer 192.168.153.133
2018/10/15 05:04:26 [INFO] agent: Started DNS server 192.168.153.133:8600 (udp)
2018/10/15 05:04:26 [WARN] agent/proxy: running as root, will not start managed proxies
2018/10/15 05:04:26 [INFO] agent: Started DNS server 192.168.153.133:8600 (tcp)
2018/10/15 05:04:26 [INFO] agent: Started HTTP server on 192.168.153.133:8500 (tcp)
2018/10/15 05:04:26 [INFO] agent: (LAN) joining: [192.168.153.129]
2018/10/15 05:04:26 [INFO] serf: EventMemberJoin: LZZ.DEV.WebServer 192.168.153.132
2018/10/15 05:04:26 [INFO] serf: EventMemberJoin: consul-3 192.168.153.131
2018/10/15 05:04:26 [INFO] serf: EventMemberJoin: consul-1 192.168.153.129
2018/10/15 05:04:26 [INFO] agent: (LAN) joined: 1 Err: <nil>
2018/10/15 05:04:26 [INFO] agent: started state syncer
2018/10/15 05:04:26 [INFO] consul: adding server consul-3 (Addr: tcp/192.168.153.131:8300) (DC: dc1)
2018/10/15 05:04:26 [INFO] consul: adding server consul-1 (Addr: tcp/192.168.153.129:8300) (DC: dc1)
2018/10/15 05:04:26 [INFO] agent: Synced node info
- -node：节点的名称
- -bind：绑定的一个地址，用于节点之间通信的地址，可以是内外网，必须是可以访问到的地址
- -server：这个就是表示这个节点是个server
- -client：这个表示这个节点是个client
- -bootstrap-expect：这个就是表示期望提供的SERVER节点数目，数目一达到，它就会被激活，然后就是LEADER了
这样，五台服务器上的consul均已配置和启动完成，接下来我们看看他们之间的关系
step7：查看所有consul成员
./consul members
Node Address Status Type Build Protocol DC Segment consul-1 192.168.153.129:8301 alive server 1.3.0 2 dc1 <all> consul-2 192.168.153.130:8301 failed server 1.3.0 2 dc1 <all> consul-3 192.168.153.131:8301 alive server 1.3.0 2 dc1 <all> LZZ.DEV.WebServer 192.168.153.132:8301 alive client 1.3.0 2 dc1 <default> LZZ.PRO.WebServer 192.168.153.133:8301 alive client 1.3.0 2 dc1 <default>
如上可知，129，130，131三台consul的类型均是server类型，而132和133为client类型，极小化的集群搭建成功
step8：查看服务成员类型
./consul operator raft list-peers
Node ID Address State Voter RaftProtocol consul-3 c612a043-8906-d6e1-8f4b-ef1c8afb3777 192.168.153.131:8300 follower true 3 consul-2 c612a043-8906-d6e1-8f4b-ef1c8afb371a 192.168.153.130:8300 follower true 3 consul-1 c612a043-8906-d6e1-8f4b-ef1c8afb371b 192.168.153.129:8300 leader true 3
由图中可知，129目前为leader类型，为了验证之前“leader随环境变化而变化”的论证，我特意输入了命令“reboot”，请接着继续看下去。
step9：关闭一台服务，测试leader状态
当129机器重新连上Consul后，我们再输入consul operator raft list-peers，可以看到此时的leader已经变为131的机器上面。
Node ID Address State Voter RaftProtocol consul-3 c612a043-8906-d6e1-8f4b-ef1c8afb3777 192.168.153.131:8300 leader true 3 consul-1 c612a043-8906-d6e1-8f4b-ef1c8afb371b 192.168.153.129:8300 follower true 3 consul-2 c612a043-8906-d6e1-8f4b-ef1c8afb371a 192.168.153.130:8300 follower true 3
所以，leader会随着环境的变化而变化，并且但只要超过一半的Server（这里是2/3还活着）还活着，集群是可以正常工作的。这也是为什么像Consul、ZooKeeper这样的分布式管理组件推荐我们使用3个或5个节点以上来部署的原因。
step10：通过WEB查看服务状态
我们还可以通过http://192.168.153.129:8500来查看整个集群的状态。
接下来，我们创建一个net core的webApi应用程序，来向consul注册一个服务。
创建ASP.NET Core程序
创建一个ASP.NET Web Application应用程序，项目名称自定
创建一个HealthController控制器，用于提示该服务的状态。
using Microsoft.AspNetCore.Mvc;
namespace LZZ.DEV.WebServer.Controllers
{
[Produces("application/json")]
[Route("api/Health")]
public class HealthController : Controller
{
[HttpGet]
public IActionResult Get() => Ok("ok");
}
}
再创建一个应用程序扩展来建立连接和注册服务，利用Net core的管道灵活特性，我们可以非常容易的建立自己的扩展
using System;
using Consul;
using LZZ.DEV.WebServer.Models;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.Hosting;
namespace LZZ.DEV.WebServer
{
public static class AppBuilderExtensions
{
public static IApplicationBuilder RegisterConsul(this IApplicationBuilder app,
IApplicationLifetime lifetime,
ServiceEntity serviceEntity)
{
var consulClient = new ConsulClient(x =>
x.Address = new Uri($"http://{serviceEntity.ConsulIP}:{serviceEntity.ConsulPort}")); //请求注册的 Consul 地址
var httpCheck = new AgentServiceCheck()
{
DeregisterCriticalServiceAfter = TimeSpan.FromSeconds(5), // 服务启动多久后注册
Interval = TimeSpan.FromSeconds(10), // 健康检查时间间隔，或者称为心跳间隔
HTTP = $"http://{serviceEntity.IP}:{serviceEntity.Port}/api/health", // 健康检查地址
Timeout = TimeSpan.FromSeconds(5) // 超时时间
};
// Register service with consul
var registration = new AgentServiceRegistration()
{
Checks = new[] {httpCheck},
ID = Guid.NewGuid().ToString(),
Name = serviceEntity.ServiceName,
Address = serviceEntity.IP,
Port = serviceEntity.Port,
Tags =
new[] {$"urlprefix-/{serviceEntity.ServiceName}"} // 添加 urlprefix-/servicename 格式的 tag 标签，以便 Fabio 识别
};
consulClient.Agent.ServiceRegister(registration).Wait(); // 服务启动时注册，内部实现其实就是使用 Consul API 进行注册（HttpClient发起）
lifetime.ApplicationStopping.Register(() =>
{
consulClient.Agent.ServiceDeregister(registration.ID).Wait(); // 服务停止时取消注册
});
return app;
}
}
}
当然，我们要使用consual，还需要安装consul依赖包
最后，我们在Startup.cs的Configure配置函数中，增加启动时注册本地条目到consual，完整代码如下
1 public void Configure(IApplicationBuilder app, IHostingEnvironment env, IApplicationLifetime lifetime)
2 {
3 app.UseMvc(routes =>
4 {
5 routes.MapRoute(
6 name: "default",
7 template: "{controller=Home}/{action=Index}/{id?}");
8 });
9
10 var serviceEntity = new ServiceEntity
11 {
12 IP = "192.168.0.196",
13 Port = Convert.ToInt32(Configuration["Service:Port"]),
14 ServiceName = Configuration["Service:Name"],
15 ConsulIP = Configuration["Consul:IP"],
16 ConsulPort = Convert.ToInt32(Configuration["Consul:Port"])
17 };
18 app.RegisterConsul(lifetime, serviceEntity);
19 }
appsettings.json配置文件如下：
1 {
2 "Service": {
3 "Name": "LZZ.DEV.ClientService",
4 "Port": "5000"
5 },
6 "Consul": {
7 "IP": "192.168.0.115",
8 "Port": "8500"
9 },
10 "Logging": {
11 "LogLevel": {
12 "Default": "Warning"
13 }
14 },
15 "AllowedHosts": "*"
16 }
好了，我们按下Ctrl+F5启动这个web应用程序瞧瞧。一切顺利，LZZ.DEV.WebServer已经被成功注册到consul中，使用相同方法也注册LZZ.PRO.WebServer到Consul中。
我们还可以通过http://192.168.153.129:8500/v1/catalog/service/LZZ.PRO.ClientService来访问consul注册这条服务的详细信息。
[
{
"ID": "c612a043-8906-d6e1-8f4b-ef1c8afb371b",
"Node": "consul-1",
"Address": "192.168.153.129",
"Datacenter": "dc1",
"TaggedAddresses": {
"lan": "192.168.153.129",
"wan": "192.168.153.129"
},
"NodeMeta": {
"consul-network-segment": ""
},
"ServiceKind": "",
"ServiceID": "81d5b247-73d1-4ae5-9d1a-208770ca4e6a",
"ServiceName": "LZZ.PRO.ClientService",
"ServiceTags": [
"urlprefix-/LZZ.PRO.ClientService"
],
"ServiceAddress": "192.168.153.132",
"ServiceWeights": {
"Passing": 1,
"Warning": 1
},
"ServiceMeta": {
},
"ServicePort": 5000,
"ServiceEnableTagOverride": false,
"ServiceProxyDestination": "",
"ServiceProxy": {
},
"ServiceConnect": {
},
"CreateIndex": 2632,
"ModifyIndex": 2632
}
]
关注ServiceAddress和ServicePort，即可完成对服务的调用。
总结
本篇主要介绍以最少化的集群创建了一个consul集群，具体各项细节都没深入研究，后续有时间我会慢慢深入，毕竟ASP.NET core天生就是一个做微服务的，感谢博客园的各位大神资料和参考。
参考
田园里的蟋蟀：《Docker & Consul & Fabio & ASP.NET Core 2.0 微服务跨平台实践》
感谢阅读！！
来源：https://www.cnblogs.com/SteveLee/p/consul_service_discovery_and_service_register.html