06、Consul：HTTP和DNS服务发现协议的支持
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
| 服务定义文件名称 | 服务名称 | tag信息 | 端口信息 |
|---|---|---|---|
| service-nginx.json | nginx | nginx-tag | 80 |
| service-tornado.json | tornado | tornado-tag | 8080 |
详细可参看：Consul服务注册示例
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
2021-02-29T15:47:04.289+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
2021-02-29T15:47:24.150+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 2021
;; 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 2021
;; 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
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来源：https://blog.csdn.net/liumiaocn/category_9752887.html