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

本文轉載自查看原文 2018-10-14 20:52 1567 NET Core/ 微服務/ 【001】NET CORE/ Rpc/ Consul/ 【002】NET微服務

Consul介紹

　　 Consul是HashiCorp公司推出的開源工具[開源地址：https://github.com/hashicorp/consul]，用於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，關於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節點用於維護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都會在運行於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。處於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

　　筆者打算通過五台Centos7來搭建Consul集群，借助VMware Workstation搭建，當然，最主要的是這台虛擬主機一定要相互ping通，最好關閉防火牆，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：

　　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，會隨着環境變化而變化（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，並安裝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。

step1：關閉防火牆

systemctl stop firewalld
systemctl disable firewalld

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

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 192.168.153.129
    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 192.168.153.130
    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：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 192.168.153.131
    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 192.168.153.132
    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 192.168.153.133
    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：節點的名稱
-bind：綁定的一個地址，用於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，五台服務器上的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，129，130，131三台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”，請接着繼續看下去。

step9：關閉一台服務，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會隨着環境的變化而變化，並且但只要超過一半的Server（這里是2/3還活着）還活着，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。

　　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，用於提示該服務的狀態。

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");
    }
}

　　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 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 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;
        }
    }
}

　　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。

　　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。

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。

參考

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

感謝閱讀！！

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