Consul：6:HTTP和DNS服务发现协议的支持

不念不忘少年蓝@ 2023-07-09 15:25 19阅读 0赞

![在这里插入图片描述][20200226162019490.jpeg_pic_center]  
这篇文章继续结合实际的例子介绍在Consul提供的HTTP协议的服务发现和DNS协议的服务发现机制。

# 事前准备 #

启动Consul并注册如下两个服务

<table> 
 <thead> 
  <tr> 
   <th>服务定义文件名称</th> 
   <th>服务名称</th> 
   <th>tag信息</th> 
   <th>端口信息</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>service-nginx.json</td> 
   <td>nginx</td> 
   <td>nginx-tag</td> 
   <td>80</td> 
  </tr> 
  <tr> 
   <td>service-tornado.json</td> 
   <td>tornado</td> 
   <td>tornado-tag</td> 
   <td>8080</td> 
  </tr> 
 </tbody> 
</table>

详细可参看：[Consul服务注册示例][Consul]

# HTTP协议方式 #

使用HTTP协议可以确认已经注册的服务信息，比如确认所做注册的服务的信息可以使用如下命令：

> 执行命令：curl http://localhost:8500/v1/catalog/services

本文示例的执行结果如下所示：

liumiaocn:~ liumiao$ curl http://localhost:8500/v1/catalog/services
    { 
        "consul": [],
        "nginx": [
            "nginx-tag"
        ],
        "tornado": [
            "tornado-tag"
        ]
    }
    liumiaocn:~ liumiao$

确认单个服务，比如本文中的nginx

> 执行命令：curl http://localhost:8500/v1/catalog/service/nginx

执行日志示例如下所示：

liumiaocn:~ liumiao$ curl http://localhost:8500/v1/catalog/service/nginx
    [
        {
            "ID": "714da227-6852-8f47-4734-acfd64f09dee",
            "Node": "liumiaocn",
            "Address": "127.0.0.1",
            "Datacenter": "dc1",
            "TaggedAddresses": {
                "lan": "127.0.0.1",
                "lan_ipv4": "127.0.0.1",
                "wan": "127.0.0.1",
                "wan_ipv4": "127.0.0.1"
            },
            "NodeMeta": {
                "consul-network-segment": ""
            },
            "ServiceKind": "",
            "ServiceID": "nginx",
            "ServiceName": "nginx",
            "ServiceTags": [
                "nginx-tag"
            ],
            "ServiceAddress": "",
            "ServiceWeights": {
                "Passing": 1,
                "Warning": 1
            },
            "ServiceMeta": {},
            "ServicePort": 80,
            "ServiceEnableTagOverride": false,
            "ServiceProxy": {
                "MeshGateway": {},
                "Expose": {}
            },
            "ServiceConnect": {},
            "CreateIndex": 12,
            "ModifyIndex": 12
        }
    ]
    liumiaocn:~ liumiao$

日志信息如下所示

2020-02-29T15:47:04.289+0800 [DEBUG] agent.http: Request finished: method=GET url=/v1/catalog/service/nginx from=127.0.0.1:49837 latency=208.383µs

确认tornado服务信息

liumiaocn:~ liumiao$ curl http://localhost:8500/v1/catalog/service/tornado
    [
        {
            "ID": "714da227-6852-8f47-4734-acfd64f09dee",
            "Node": "liumiaocn",
            "Address": "127.0.0.1",
            "Datacenter": "dc1",
            "TaggedAddresses": {
                "lan": "127.0.0.1",
                "lan_ipv4": "127.0.0.1",
                "wan": "127.0.0.1",
                "wan_ipv4": "127.0.0.1"
            },
            "NodeMeta": {
                "consul-network-segment": ""
            },
            "ServiceKind": "",
            "ServiceID": "tornado",
            "ServiceName": "tornado",
            "ServiceTags": [
                "tornado-tag"
            ],
            "ServiceAddress": "",
            "ServiceWeights": {
                "Passing": 1,
                "Warning": 1
            },
            "ServiceMeta": {},
            "ServicePort": 8080,
            "ServiceEnableTagOverride": false,
            "ServiceProxy": {
                "MeshGateway": {},
                "Expose": {}
            },
            "ServiceConnect": {},
            "CreateIndex": 13,
            "ModifyIndex": 13
        }
    ]
    liumiaocn:~ liumiao$

执行日志信息如下所示

2020-02-29T15:47:24.150+0800 [DEBUG] agent.http: Request finished: method=GET url=/v1/catalog/service/tornado from=127.0.0.1:49860 latency=147.932µs

# DNS协议方式 #

DNS在Consul中缺省情况下的服务注册为NMAE.service.consul，所以本文示例的两个服务分别是nginx.service.consul和tornado.service.consul，以nginx服务为例，详细的信息如下所示：

liumiaocn:~ liumiao$ dig @127.0.0.1 -p 8600 nginx.service.consul
    
    ; <<>> DiG 9.10.6 <<>> @127.0.0.1 -p 8600 nginx.service.consul
    ; (1 server found)
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20037
    ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
    ;; WARNING: recursion requested but not available
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;nginx.service.consul.		IN	A
    
    ;; ANSWER SECTION:
    nginx.service.consul.	0	IN	A	127.0.0.1
    
    ;; Query time: 1 msec
    ;; SERVER: 127.0.0.1#8600(127.0.0.1)
    ;; WHEN: Sat Feb 29 15:55:43 CST 2020
    ;; MSG SIZE  rcvd: 65
    
    liumiaocn:~ liumiao$

然后也可以加上SRV查看更加详细的信息

liumiaocn:~ liumiao$ dig @127.0.0.1 -p 8600 nginx.service.consul SRV
    
    ; <<>> DiG 9.10.6 <<>> @127.0.0.1 -p 8600 nginx.service.consul SRV
    ; (1 server found)
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42007
    ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 3
    ;; WARNING: recursion requested but not available
    
    ;; OPT PSEUDOSECTION:
    ; EDNS: version: 0, flags:; udp: 4096
    ;; QUESTION SECTION:
    ;nginx.service.consul.		IN	SRV
    
    ;; ANSWER SECTION:
    nginx.service.consul.	0	IN	SRV	1 1 80 liumiaocn.node.dc1.consul.
    
    ;; ADDITIONAL SECTION:
    liumiaocn.node.dc1.consul. 0	IN	A	127.0.0.1
    liumiaocn.node.dc1.consul. 0	IN	TXT	"consul-network-segment="
    
    ;; Query time: 0 msec
    ;; SERVER: 127.0.0.1#8600(127.0.0.1)
    ;; WHEN: Sat Feb 29 15:57:02 CST 2020
    ;; MSG SIZE  rcvd: 146
    
    liumiaocn:~ liumiao$

# 参考内容 #

https://learn.hashicorp.com/consul/getting-started/services?utm\_source=consul.io&utm\_medium=docs

[20200226162019490.jpeg_pic_center]: https://img-blog.csdnimg.cn/20200226162019490.jpeg#pic_center
[Consul]: https://liumiaocn.blog.csdn.net/article/details/104571356