每天早上七點三十，準時推送幹貨
Hello 大家好，我是阿粉，前面的文章給大家介紹過 Nacos，用于服務注冊發現和管理配置的開源元件，今天給大家分享另一個元件 Consul 也有相應的功能，我們一起來看一下吧！
背景
目前分布式系統架構已經基本普及，很多項目都是基于分布式架構的，以往的單機模式基本已經不适應當下網際網路行業的發展。随着分布式項目的普及，項目服務執行個體數目的增加，服務的注冊與發現功能就成了一項必不可少的架構。服務的注冊與發現的功能，有很多開源方案。包括早期的zookeeper，百度的disconf，阿裡的diamond，基于Go語言的ETCD，Spring內建的Eureka，以及前文提到的 Nacos 還有本文的主角Consul。這裡不對上面提到的進行比較，本文僅介紹Consul，詳細的對比，說明網上有很多資料，可以參考，例如：服務發現比較:Consul vs Zookeeper vs Etcd vs Eureka說到服務的注冊與發現主要是下面兩個主要功能：
- 服務注冊與發現
- 配置中心即分布式項目統一配置管理
Consul 簡介
- Consul采用Go語言開發
- Consul内置服務注冊與發現架構、分布一緻性協定實作、健康檢查、Key/Value存儲、多資料中心方案；不依賴其他工具，安裝包包含一個可執行檔案
- 支援DNS、HTTP協定接口
- 自帶web-ui
- Consul是 HashiCorp 公司推出的開源工具，用于實作分布式系統的服務發現與配置。
- Consul支援兩種服務注冊的方式，一種是通過Consul的服務注冊HTTP API，由服務自身在啟動後調用API注冊自己，另外一種則是通過在配置檔案中定義服務的方式進行注冊。Consul文檔中建議使用後面一種方式來做服務 配置和服務注冊。
Consul 服務端配置使用
- 下載下傳相應版本解壓，并将可執行檔案複制到/usr/local/consul目錄下
- 建立一個service的配置檔案
silence$ sudo mkdir /etc/consul.d silence$ echo '{"service":{"name": "web", "tags": ["rails"], "port": 80}}' | sudo tee /etc/consul.d/web.json - 啟動代理
silence$ /usr/local/consul/consul agent -dev -node consul_01 -config-dir=/etc/consul.d/ -ui-dev 參數代表本地測試環境啟動；-node 參數表示自定義叢集名稱；-config-drir 參數表示services的注冊配置檔案目錄，即上面建立的檔案夾-ui 啟動自帶的web-ui管理頁面
- 叢集成員查詢方式
silence-pro:~ silence$ /usr/local/consul/consul members - HTTP協定資料查詢
silence-pro:~ silence$ curl http://127.0.0.1:8500/v1/catalog/service/web [ { "ID": "ab1e3577-1b24-d254-f55e-9e8437956009", "Node": "consul_01", "Address": "127.0.0.1", "Datacenter": "dc1", "TaggedAddresses": { "lan": "127.0.0.1", "wan": "127.0.0.1" }, "NodeMeta": { "consul-network-segment": "" }, "ServiceID": "web", "ServiceName": "web", "ServiceTags": [ "rails" ], "ServiceAddress": "", "ServicePort": 80, "ServiceEnableTagOverride": false, "CreateIndex": 6, "ModifyIndex": 6 } ] silence-pro:~ silence$ - web-ui管理
Consul Web UI
Consul的web-ui可以用來進行服務狀态的檢視，叢集節點的檢查，通路清單的控制以及KV存儲系統的設定，相對于Eureka和ETCD，Consul的web-ui要好用的多。（Eureka和ETCD将在下一篇文章中簡單介紹。）
7. KV存儲的資料導入和導出
silence-pro:consul silence$ ./consul kv import @temp.json
silence-pro:consul silence$ ./consul kv export redis/
temp.json檔案内容格式如下，一般是管理頁面配置後先導出儲存檔案，以後需要再導入該檔案
[
{
"key": "redis/config/password",
"flags": 0,
"value": "MTIzNDU2"
},
{
"key": "redis/config/username",
"flags": 0,
"value": "U2lsZW5jZQ=="
},
{
"key": "redis/zk/",
"flags": 0,
"value": ""
},
{
"key": "redis/zk/password",
"flags": 0,
"value": "NDU0NjU="
},
{
"key": "redis/zk/username",
"flags": 0,
"value": "ZGZhZHNm"
}
]
Consul的KV存儲系統是一種類似zk的樹形節點結構，用來存儲相關key/value鍵值對資訊的，我們可以使用KV存儲系統來實作上面提到的配置中心，将統一的配置資訊儲存在KV存儲系統裡面，友善各個執行個體擷取并使用同一配置。而且更改配置後各個服務可以自動拉取最新配置，不需要重新開機服務。
Consul Java 用戶端使用
- maven pom依賴增加，版本可自由更換
<dependency> <groupId>com.orbitz.consul</groupId> <artifactId>consul-client</artifactId> <version>0.12.3</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> - Consul 基本工具類，根據需要相應擴充
package com.coocaa.consul.consul.demo; import com.google.common.base.Optional; import com.google.common.net.HostAndPort; import com.orbitz.consul.*; import com.orbitz.consul.model.agent.ImmutableRegCheck; import com.orbitz.consul.model.agent.ImmutableRegistration; import com.orbitz.consul.model.health.ServiceHealth; import java.net.MalformedURLException; import java.net.URI; import java.util.List; public class ConsulUtil { private static Consul consul = Consul.builder().withHostAndPort(HostAndPort.fromString("127.0.0.1:8500")).build(); /** * 服務注冊 */ public static void serviceRegister() { AgentClient agent = consul.agentClient(); try { /** * 注意該注冊接口： * 需要提供一個健康檢查的服務URL，以及每隔多長時間通路一下該服務（這裡是3s） */ agent.register(8080, URI.create("http://localhost:8080/health").toURL(), 3, "tomcat", "tomcatID", "dev"); } catch (MalformedURLException e) { e.printStackTrace(); } } /** * 服務擷取 * * @param serviceName */ public static void findHealthyService(String serviceName) { HealthClient healthClient = consul.healthClient(); List<ServiceHealth> serviceHealthList = healthClient.getHealthyServiceInstances(serviceName).getResponse(); serviceHealthList.forEach((response) -> { System.out.println(response); }); } /** * 存儲KV */ public static void storeKV(String key, String value) { KeyValueClient kvClient = consul.keyValueClient(); kvClient.putValue(key, value); } /** * 根據key擷取value */ public static String getKV(String key) { KeyValueClient kvClient = consul.keyValueClient(); Optional<String> value = kvClient.getValueAsString(key); if (value.isPresent()) { return value.get(); } return ""; } /** * 找出一緻性的節點（應該是同一個DC中的所有server節點） */ public static List<String> findRaftPeers() { StatusClient statusClient = consul.statusClient(); return statusClient.getPeers(); } /** * 擷取leader */ public static String findRaftLeader() { StatusClient statusClient = consul.statusClient(); return statusClient.getLeader(); } public static void main(String[] args) { AgentClient agentClient = consul.agentClient(); agentClient.deregister("tomcatID"); } }temp.json 和 ConsulUtil.java 檔案以及上傳到 GitHub 資源庫，回複【源碼倉庫】擷取代碼位址。
- 通過上面的基本工具類可以實作服務的注冊和KV資料的擷取與存儲功能
Consul叢集搭建
參考位址 Consul叢集搭建 http://ju.outofmemory.cn/entry/189899
- 三台主機Consul下載下傳安裝，我這裡沒有實體主機，是以通過三台虛拟機來實作。虛拟機IP分192.168.231.145，192.168.231.146，192.168.231.147
- 将145和146兩台主機作為Server模式啟動，147作為Client模式啟動，Server和Client隻是針對Consul叢集來說的，跟服務沒有任何關系！
- Server模式啟動145，節點名稱設為n1，資料中心統一用dc1
[[email protected] consul]# ./consul agent -server -bootstrap-expect 2 -data-dir /tmp/consul -node=n1 -bind=192.168.231.145 -datacenter=dc1 bootstrap_expect = 2: A cluster with 2 servers will provide no failure tolerance. See https://www.consul.io/docs/internals/consensus.html#deployment-table bootstrap_expect > 0: expecting 2 servers ==> Starting Consul agent... ==> Consul agent running! Version: 'v1.0.1' Node ID: '6cc74ff7-7026-cbaa-5451-61f02114cd25' Node name: 'n1' Datacenter: 'dc1' (Segment: '<all>') Server: true (Bootstrap: false) Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, DNS: 8600) Cluster Addr: 192.168.231.145 (LAN: 8301, WAN: 8302) Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false ==> Log data will now stream in as it occurs: 2017/12/06 23:26:21 [INFO] raft: Initial configuration (index=0): [] 2017/12/06 23:26:21 [INFO] serf: EventMemberJoin: n1.dc1 192.168.231.145 2017/12/06 23:26:21 [INFO] serf: EventMemberJoin: n1 192.168.231.145 2017/12/06 23:26:21 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp) 2017/12/06 23:26:21 [INFO] raft: Node at 192.168.231.145:8300 [Follower] entering Follower state (Leader: "") 2017/12/06 23:26:21 [INFO] consul: Adding LAN server n1 (Addr: tcp/192.168.231.145:8300) (DC: dc1) 2017/12/06 23:26:21 [INFO] consul: Handled member-join event for server "n1.dc1" in area "wan" 2017/12/06 23:26:21 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp) 2017/12/06 23:26:21 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp) 2017/12/06 23:26:21 [INFO] agent: started state syncer 2017/12/06 23:26:28 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:26:30 [WARN] raft: no known peers, aborting election 2017/12/06 23:26:49 [ERR] agent: Coordinate update error: No cluster leader 2017/12/06 23:26:54 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:27:24 [ERR] agent: Coordinate update error: No cluster leader 2017/12/06 23:27:27 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:27:56 [ERR] agent: Coordinate update error: No cluster leader 2017/12/06 23:28:02 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:28:27 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:28:33 [ERR] agent: Coordinate update error: No cluster leader目前隻啟動了145，是以還沒有叢集
- Server模式啟動146，節點名稱用n2，并在n2上啟用了web-ui管理頁面功能
[[email protected] consul]# ./consul agent -server -bootstrap-expect 2 -data-dir /tmp/consul -node=n2 -bind=192.168.231.146 -datacenter=dc1 -ui bootstrap_expect = 2: A cluster with 2 servers will provide no failure tolerance. See https://www.consul.io/docs/internals/consensus.html#deployment-table bootstrap_expect > 0: expecting 2 servers ==> Starting Consul agent... ==> Consul agent running! Version: 'v1.0.1' Node ID: 'eb083280-c403-668f-e193-60805c7c856a' Node name: 'n2' Datacenter: 'dc1' (Segment: '<all>') Server: true (Bootstrap: false) Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, DNS: 8600) Cluster Addr: 192.168.231.146 (LAN: 8301, WAN: 8302) Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false ==> Log data will now stream in as it occurs: 2017/12/06 23:28:30 [INFO] raft: Initial configuration (index=0): [] 2017/12/06 23:28:30 [INFO] serf: EventMemberJoin: n2.dc1 192.168.231.146 2017/12/06 23:28:31 [INFO] serf: EventMemberJoin: n2 192.168.231.146 2017/12/06 23:28:31 [INFO] raft: Node at 192.168.231.146:8300 [Follower] entering Follower state (Leader: "") 2017/12/06 23:28:31 [INFO] consul: Adding LAN server n2 (Addr: tcp/192.168.231.146:8300) (DC: dc1) 2017/12/06 23:28:31 [INFO] consul: Handled member-join event for server "n2.dc1" in area "wan" 2017/12/06 23:28:31 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp) 2017/12/06 23:28:31 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp) 2017/12/06 23:28:31 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp) 2017/12/06 23:28:31 [INFO] agent: started state syncer 2017/12/06 23:28:38 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:28:39 [WARN] raft: no known peers, aborting election 2017/12/06 23:28:57 [ERR] agent: Coordinate update error: No cluster leader 2017/12/06 23:29:11 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:29:30 [ERR] agent: Coordinate update error: No cluster leader 2017/12/06 23:29:38 [ERR] agent: failed to sync remote state: No cluster leader 2017/12/06 23:29:57 [ERR] agent: Coordinate update error: No cluster leader同樣沒有叢集發現，此時n1和n2都啟動起來，但是互相并不知道叢集的存在！
- 将n1節點加入n2
[[email protected] consul]$ ./consul join 192.168.231.146此時n1和n2都列印發現了叢集的日志資訊
- 這個時候n1和n2兩個節點已經是一個叢集裡面的Server模式的節點了
- Client模式啟動147
[[email protected] consul]# ./consul agent -data-dir /tmp/consul -node=n3 -bind=192.168.231.147 -datacenter=dc1 ==> Starting Consul agent... ==> Consul agent running! Version: 'v1.0.1' Node ID: 'be7132c3-643e-e5a2-9c34-cad99063a30e' Node name: 'n3' Datacenter: 'dc1' (Segment: '') Server: false (Bootstrap: false) Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, DNS: 8600) Cluster Addr: 192.168.231.147 (LAN: 8301, WAN: 8302) Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false ==> Log data will now stream in as it occurs: 2017/12/06 23:36:46 [INFO] serf: EventMemberJoin: n3 192.168.231.147 2017/12/06 23:36:46 [INFO] agent: Started DNS server 127.0.0.1:8600 (udp) 2017/12/06 23:36:46 [INFO] agent: Started DNS server 127.0.0.1:8600 (tcp) 2017/12/06 23:36:46 [INFO] agent: Started HTTP server on 127.0.0.1:8500 (tcp) 2017/12/06 23:36:46 [INFO] agent: started state syncer 2017/12/06 23:36:46 [WARN] manager: No servers available 2017/12/06 23:36:46 [ERR] agent: failed to sync remote state: No known Consul servers 2017/12/06 23:37:08 [WARN] manager: No servers available 2017/12/06 23:37:08 [ERR] agent: failed to sync remote state: No known Consul servers 2017/12/06 23:37:36 [WARN] manager: No servers available 2017/12/06 23:37:36 [ERR] agent: failed to sync remote state: No known Consul servers 2017/12/06 23:38:02 [WARN] manager: No servers available 2017/12/06 23:38:02 [ERR] agent: failed to sync remote state: No known Consul servers 2017/12/06 23:38:22 [WARN] manager: No servers available 2017/12/06 23:38:22 [ERR] agent: failed to sync remote state: No known Consul servers - 在n3上面将節點n3加入叢集
[[email protected] consul]$ ./consul join 192.168.231.145 - 再次檢視叢集節點資訊
- 此時三個節點的Consul叢集搭建成功了！其實n1和n2是Server模式啟動，n3是Client模式啟動。
- 關于Consul的Server模式和Client模式主要的差別是這樣的，一個Consul叢集通過啟動的參數
-bootstrap-expect
- 在n2中啟動web-ui
分布式服務注冊發現與統一配置管理之 Consul背景Consul 簡介
最後說兩句（求關注）
最近大家應該發現微信公衆号資訊流改版了吧，再也不是按照時間順序展示了。這就對阿粉這樣的堅持的原創小号主，可以說非常打擊，閱讀量直線下降，正回報持續減弱。
是以看完文章，哥哥姐姐們給阿粉來個在看吧，讓阿粉擁有更加大的動力，寫出更好的文章，拒絕白嫖，來點正回報呗~。
如果想在第一時間收到阿粉的文章，不被公号的資訊流影響，那麼可以給Java極客技術設為一個星标。
最後感謝各位的閱讀，才疏學淺，難免存在纰漏，如果你發現錯誤的地方，由于本号沒有留言功能，還請你在背景留言指出，我對其加以修改。
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最最後，重要的事再說一篇~
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如果大家喜歡我們的文章，歡迎大家轉發，點選在看讓更多的人看到。也歡迎大家熱愛技術和學習的朋友加入的我們的知識星球當中，我們共同成長，進步。
往期精彩回顧
SpringBoot2.x 整合 shiro 權限架構
什麼是BIO，NIO？他們和多路複用器有啥關系？
你應該知道的 Nacos 接入和避坑指南