原文:.NET Core微服務之路：基于Consul最少集群實現服務的注冊與發現（一）

Consul介紹

　　Consul是HashiCorp公司推出的開源工具[開源地址：https://github.com/hashicorp/consul]，用于實現分布式系統的服務發現與配置。 　　與市面上其他系統比較如下： ? 　　總體而言， Consul用Golang實現，因此具有天然可移植性（支持Linux、windows和Mac OS X）；安裝包僅包含一個可執行文件，方便部署，與Docker等輕量級容器可無縫配合。 此外，關于Consul的架構以及相關的角色，如下圖所示： 　　以Server模式運行的Consul Agent節點用于維護Consul集群的狀態，官方建議每個Consul Cluster至少有3個或以上的運行在Server Mode的Agent，Client節點不限。Consul支持多數據中心，每個數據中心的Consul Cluster都會在運行于Server模式下的Agent節點中選出一個Leader節點，這個選舉過程通過Consul實現的raft協議保證，多個 Server節點上的Consul數據信息是強一致的。處于Client Mode的Consul Agent節點比較簡單，無狀態，僅僅負責將請求轉發給Server Agent節點。 ?

集群搭建

　　筆者打算通過五臺Centos7來搭建Consul集群，借助VMware Workstation搭建，當然，最主要的是這臺虛擬主機一定要相互ping通，最好關閉防火墻，而且，虛擬機也需要和宿主機（實比如筆者的Windows10操作系統）ping通，具體問題和配置可搜索一下，圖片如下：

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其中130作為leader角色，129和131作為follower角色，當然，在實際環境中，leader的角色不一定是固定的，會隨著環境變化而變化（比如網絡斷了、宕機了等等）這個我們后續來驗證。132和133作為客戶端，并安裝NET Core 2.1環境，再次提示，一定要保證在這個環境中的所有系統相互之間均能Ping通。

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step1：關閉防火墻

systemctl stop firewalld systemctl disable firewalld

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step2：安裝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

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step3：節點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 #設置129為服務器 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 192.168.153.1292018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-1 192.168.153.1292018/10/15 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 1m0s2018/10/15 04:53:30 [WARN] agent: check 'service:81d5b247-73d1-4ae5-9d1a-208770ca4e6a' has deregister interval below minimum of 1m0s2018/10/15 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: 192.168.153.131:83022018/10/15 04:53:30 [INFO] serf: Attempting re-join to previously known node: LZZ.PRODUCTS.WebServer: 192.168.153.133:83012018/10/15 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 mode2018/10/15 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 proxies2018/10/15 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 syncer2018/10/15 04:53:30 [INFO] serf: Attempting re-join to previously known node: consul-3: 192.168.153.131:83012018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-3.dc1 192.168.153.1312018/10/15 04:53:30 [WARN] memberlist: Refuting an alive message2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-2.dc1 192.168.153.1302018/10/15 04:53:30 [INFO] serf: Re-joined to previously known node: consul-3.dc1: 192.168.153.131:83022018/10/15 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-3 192.168.153.1312018/10/15 04:53:30 [WARN] memberlist: Refuting a suspect message (from: consul-1)2018/10/15 04:53:30 [INFO] serf: EventMemberJoin: consul-2 192.168.153.1302018/10/15 04:53:30 [INFO] serf: Re-joined to previously known node: consul-3: 192.168.153.131:83012018/10/15 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)

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Client Addr的地址是[0.0.0.0]，代表本機上的所有IPv4地址。集群地址是：192.168.153.129。稍后我們介紹命令一些主要參數的的作用。

step4：節點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 192.168.153.1302018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-2 192.168.153.1302018/10/15 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: 192.168.153.131:83022018/10/15 04:56:36 [INFO] serf: Attempting re-join to previously known node: consul-3: 192.168.153.131:83012018/10/15 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 mode2018/10/15 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-1 192.168.153.1292018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-3 192.168.153.1312018/10/15 04:56:36 [INFO] serf: Re-joined to previously known node: consul-3: 192.168.153.131:83012018/10/15 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 192.168.153.1292018/10/15 04:56:36 [INFO] serf: EventMemberJoin: consul-3.dc1 192.168.153.1312018/10/15 04:56:36 [INFO] serf: Re-joined to previously known node: consul-3.dc1: 192.168.153.131:83022018/10/15 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 proxies2018/10/15 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：節點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 192.168.153.1312018/10/15 05:01:15 [INFO] serf: EventMemberJoin: consul-3 192.168.153.1312018/10/15 05:01:15 [INFO] serf: Attempting re-join to previously known node: consul-1.dc1: 192.168.153.129:83022018/10/15 05:01:15 [INFO] serf: Attempting re-join to previously known node: consul-1: 192.168.153.129:83012018/10/15 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 mode2018/10/15 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 proxies2018/10/15 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-1 192.168.153.1292018/10/15 05:01:15 [INFO] serf: Re-joined to previously known node: consul-1: 192.168.153.129:83012018/10/15 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 192.168.153.1292018/10/15 05:01:15 [INFO] serf: Re-joined to previously known node: consul-1.dc1: 192.168.153.129:83022018/10/15 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：客戶端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 192.168.153.1322018/10/15 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 proxies2018/10/15 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-1 192.168.153.1292018/10/15 05:03:15 [INFO] serf: EventMemberJoin: consul-3 192.168.153.1312018/10/15 05:03:15 [INFO] agent: (LAN) joined: 1 Err: <nil>2018/10/15 05:03:15 [INFO] agent: started state syncer2018/10/15 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

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step6：客戶端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 192.168.153.1332018/10/15 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 proxies2018/10/15 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 192.168.153.1322018/10/15 05:04:26 [INFO] serf: EventMemberJoin: consul-3 192.168.153.1312018/10/15 05:04:26 [INFO] serf: EventMemberJoin: consul-1 192.168.153.1292018/10/15 05:04:26 [INFO] agent: (LAN) joined: 1 Err: <nil>2018/10/15 05:04:26 [INFO] agent: started state syncer2018/10/15 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

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• -node：節點的名稱
• -bind：綁定的一個地址，用于節點之間通信的地址，可以是內外網，必須是可以訪問到的地址
• -server：這個就是表示這個節點是個server
• -client：這個表示這個節點是個client
• -bootstrap-expect：這個就是表示期望提供的SERVER節點數目，數目一達到，它就會被激活，然后就是LEADER了

這樣，五臺服務器上的consul均已配置和啟動完成，接下來我們看看他們之間的關系

step7：查看所有consul成員

./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，129，130，131三臺consul的類型均是server類型，而132和133為client類型，極小化的集群搭建成功

step8：查看服務成員類型

./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

?　　由圖中可知，129目前為leader類型，為了驗證之前“leader隨環境變化而變化”的論證，我特意輸入了命令“reboot”，請接著繼續看下去。

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step9：關閉一臺服務，測試leader狀態

　　當129機器重新連上Consul后，我們再輸入consul operator raft list-peers，可以看到此時的leader已經變為131的機器上面。 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會隨著環境的變化而變化，并且但只要超過一半的Server（這里是2/3還活著）還活著，集群是可以正常工作的。這也是為什么像Consul、ZooKeeper這樣的分布式管理組件推薦我們使用3個或5個節點以上來部署的原因。

step10：通過WEB查看服務狀態

　　我們還可以通過http://192.168.153.129:8500來查看整個集群的狀態。

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接下來，我們創建一個net core的webApi應用程序，來向consul注冊一個服務。 ?

創建ASP.NET?Core程序

　　創建一個ASP.NET Web Application應用程序，項目名稱自定

創建一個HealthController控制器，用于提示該服務的狀態。 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");} }

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?　　再創建一個應用程序擴展來建立連接和注冊服務，利用Net core的管道靈活特性，我們可以非常容易的建立自己的擴展

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}")); //請求注冊的 Consul 地址var httpCheck = new AgentServiceCheck(){DeregisterCriticalServiceAfter = TimeSpan.FromSeconds(5), // 服務啟動多久后注冊Interval = TimeSpan.FromSeconds(10), // 健康檢查時間間隔，或者稱為心跳間隔HTTP = $"http://{serviceEntity.IP}:{serviceEntity.Port}/api/health", // 健康檢查地址Timeout = TimeSpan.FromSeconds(5) // 超時時間 };// Register service with consulvar registration = new AgentServiceRegistration(){Checks = new[] {httpCheck},ID = Guid.NewGuid().ToString(),Name = serviceEntity.ServiceName,Address = serviceEntity.IP,Port = serviceEntity.Port,Tags =new[] {$"urlprefix-/{serviceEntity.ServiceName}"} // 添加 urlprefix-/servicename 格式的 tag 標簽，以便 Fabio 識別 };consulClient.Agent.ServiceRegister(registration).Wait(); // 服務啟動時注冊，內部實現其實就是使用 Consul API 進行注冊（HttpClient發起）lifetime.ApplicationStopping.Register(() =>{consulClient.Agent.ServiceDeregister(registration.ID).Wait(); // 服務停止時取消注冊 });return app;}} }

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　　當然，我們要使用consual，還需要安裝consul依賴包 ?　　最后，我們在Startup.cs的Configure配置函數中，增加啟動時注冊本地條目到consual，完整代碼如下 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，我們按下Ctrl+F5啟動這個web應用程序瞧瞧。一切順利，LZZ.DEV.WebServer已經被成功注冊到consul中，使用相同方法也注冊LZZ.PRO.WebServer到Consul中。 ?

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我們還可以通過http://192.168.153.129:8500/v1/catalog/service/LZZ.PRO.ClientService來訪問consul注冊這條服務的詳細信息。 ? [{"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} ]

　　關注ServiceAddress和ServicePort，即可完成對服務的調用。

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總結

　　本篇主要介紹以最少化的集群創建了一個consul集群，具體各項細節都沒深入研究，后續有時間我會慢慢深入，畢竟ASP.NET core天生就是一個做微服務的，感謝博客園的各位大神資料和參考。

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參考

　　田園里的蟋蟀：《Docker & Consul & Fabio & ASP.NET Core 2.0 微服務跨平臺實踐》

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感謝閱讀！！

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