Consul介紹
Consul是HashiCorp公司推出的開源工具[開源位址：https://github.com/hashicorp/consul]，用于實作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實作，是以具有天然可移植性（支援Linux、windows和Mac OS X）；安裝包僅包含一個可執行檔案，友善部署，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模式運作的Consul Agent節點用于維護Consul叢集的狀态，官方建議每個Consul Cluster至少有3個或以上的運作在Server Mode的Agent，Client節點不限。Consul支援多資料中心，每個資料中心的Consul Cluster都會在運作于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實作的raft協定保證，多個 Server節點上的Consul資料資訊是強一緻的。處于Client Mode的Consul Agent節點比較簡單，無狀态，僅僅負責将請求轉發給Server Agent節點。
叢集搭建
筆者打算通過五台Centos7來搭建Consul叢集，借助VMware Workstation搭建，當然，最主要的是這台虛拟主機一定要互相ping通，最好關閉防火牆，而且，虛拟機也需要和主控端（實比如筆者的Windows10作業系統）ping通，具體問題和配置可搜尋一下，圖檔如下：
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，會随着環境變化而變化（比如網絡斷了、當機了等等）這個我們後續來驗證。132和133作為用戶端，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互相之間均能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 #設定129為伺服器 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的位址是[0.0.0.0]，代表本機上的所有IPv4位址。叢集位址是：192.168.153.129。稍後我們介紹指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：用戶端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：用戶端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：綁定的一個位址，用于節點之間通信的位址，可以是内外網，必須是可以通路到的位址
- -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，然後就是LEADER了
這樣，五台伺服器上的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：檢視所有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，極小化的叢集搭建成功
step8：檢視服務成員類型
./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随環境變化而變化”的論證，我特意輸入了指令“reboot”，請接着繼續看下去。
step9：關閉一台服務，測試leader狀态
當129機器重新連上Consul後，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 是以，leader會随着環境的變化而變化，并且但隻要超過一半的Server（這裡是2/3還活着）還活着，叢集是可以正常工作的。這也是為什麼像Consul、ZooKeeper這樣的分布式管理元件推薦我們使用3個或5個節點以上來部署的原因。
step10：通過WEB檢視服務狀态
我們還可以通過http://192.168.153.129:8500來檢視整個叢集的狀态。
接下來，我們建立一個net core的webApi應用程式，來向consul注冊一個服務。
建立ASP.NET Core程式
建立一個ASP.NET Web Application應用程式，項目名稱自定
建立一個HealthController控制器，用于提示該服務的狀态。
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");
}
} 再建立一個應用程式擴充來建立連接配接和注冊服務，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充
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 位址
var httpCheck = new AgentServiceCheck()
{
DeregisterCriticalServiceAfter = TimeSpan.FromSeconds(5), // 服務啟動多久後注冊
Interval = TimeSpan.FromSeconds(10), // 健康檢查時間間隔，或者稱為心跳間隔
HTTP = $"http://{serviceEntity.IP}:{serviceEntity.Port}/api/health", // 健康檢查位址
Timeout = TimeSpan.FromSeconds(5) // 逾時時間
};
// Register service with consul
var registration = new AgentServiceRegistration()
{
Checks = new[] {httpCheck},
ID = Guid.NewGuid().ToString(),
Name = serviceEntity.ServiceName,
Address = serviceEntity.IP,
Port = serviceEntity.Port,
Tags =
new[] {$"urlprefix-/{serviceEntity.ServiceName}"} // 添加 urlprefix-/servicename 格式的 tag 标簽，以便 Fabio 識别
};
consulClient.Agent.ServiceRegister(registration).Wait(); // 服務啟動時注冊，内部實作其實就是使用 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
最後，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配置檔案如下：
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應用程式瞧瞧。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來通路consul注冊這條服務的詳細資訊。
[
{
"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叢集建立了一個consul叢集，具體各項細節都沒深入研究，後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，感謝部落格園的各位大神資料和參考。
參考
田園裡的蟋蟀：《
Docker & Consul & Fabio & ASP.NET Core 2.0 微服務跨平台實踐》
感謝閱讀！！