[英]Consul service discovery with DNS on Nodejs
大家好,我試圖從Express編寫的nodejs前端調用nodejs后端微服務,通過Consul DNS接口,但我有錯誤。
我使用nodejs dns api為唯一的節點應用程序設置dns,以便對本地Consul DNS接口進行后續的dns.resolve()調用。
我希望能夠向我的后端服務發出http請求,而無需在我的客戶端代碼中連接其IP和端口。 我不想編寫自定義代碼來查詢Consul HTTP API,以便在我需要調用它時獲取我的服務的ip:port couple。
問題是,當我使用axios (類似於請求 )對后端服務進行HTTP調用時,我總是會收到錯誤,因為它無法解析地址。 似乎Axios沒有使用我之前設置的dns:
dns.setServers(['127.0.0.1:8600']);
使用-recursor命令行選項將虛擬機的dns(/etc/resolv.conf)設置為localhost,使用默認dns的consul一切正常! 我仍然想了解我在我的nodejs應用程序上設置dns的錯誤。
在FE節點上運行consul成員我得到:
agent-server 10.0.1.7:8301 alive server 1.0.1 2 dc1 <all>
agent-be-01 10.0.1.5:8301 alive client 1.0.1 2 dc1 <default>
agent-be-02 10.0.1.6:8301 alive client 1.0.1 2 dc1 <default>
agent-fe 10.0.1.4:8301 alive client 1.0.1 2 dc1 <default>
如果我在FE節點上運行挖掘@localhost -p 8600 be01.service.consul SRV我正確得到了這個結果( 如在Consul文檔中 ):
root@NGINXLB:~/node8080$ dig @localhost -p 8600 be01.service.consul SRV
; <<>> DiG 9.9.5-3ubuntu0.16-Ubuntu <<>> @localhost -p 8600 be01.service.consul SRV
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43367
;; flags: qr aa rd; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 5
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;be01.service.consul. IN SRV
;; ANSWER SECTION:
be01.service.consul. 0 IN SRV 1 1 8081 agent-be-02.node.dc1.consul.
be01.service.consul. 0 IN SRV 1 1 8080 agent-be-01.node.dc1.consul.
;; ADDITIONAL SECTION:
agent-be-02.node.dc1.consul. 0 IN A 10.0.1.6
agent-be-02.node.dc1.consul. 0 IN TXT "consul-network-segment="
agent-be-01.node.dc1.consul. 0 IN A 10.0.1.5
agent-be-01.node.dc1.consul. 0 IN TXT "consul-network-segment="
;; Query time: 2 msec
;; SERVER: 127.0.0.1#8600(127.0.0.1)
;; WHEN: Fri Dec 01 10:09:00 UTC 2017
;; MSG SIZE rcvd: 246
這是BE服務代碼:
var express = require('express');
var bodyParser = require('body-parser');
var app = express();
var jsonParser = bodyParser.json()
var urlencodedParser = bodyParser.urlencoded({ extended: false })
app.post('/api/getUserTiles', jsonParser, function (req, res) {
console.log("> API request for '/api/getUserTiles'");
if (!req.body) { return res.sendStatus(400) }
else {
var user = req.body.user;
console.log("User: " + user);
res.json({
"authorizedTiles": [
{"tileID": "profile"}
,{"tileID": "search"}
,{"tileID": "test"}
],
"email": "max@google.com",
"userName":"Max",
"has_error": false,
"error_message": ""
});
}
});
var server = app.listen(8080, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port)
})
使用帶有curl的ip:port從FE調用它可以正常工作:
root@NGINXLB:~/node8080$ curl -d="user=Max" -X POST http://10.0.1.5:8080/api/getUserTiles
{"authorizedTiles":[{"tileID":"profile"},{"tileID":"search"},{"tileID":"test"}],"email":"max@google.com","userName":"Max","has_error":false,"error_message":""}
FE節點上的Web服務,簡化,是這樣的:
var axios = require('axios');
var dns = require('dns');
var consul = require('consul')();
dns.setServers(['127.0.0.1:8600']);
//console.log(dns.getServers());
dns.resolveSrv("be01.service.consul", function(err, records){
console.log("\nDNS SRV query");
if(err){
console.log(err);
}else{
console.log(records);
}
});
consul.health.service({
"service": "be01",
"dc": "dc1",
"passing": true
}, function(err, result){
console.log("\nConsul.health.service query:");
if(err){console.log(err); throw err;}
else if(result.length > 0){
for(var i=0; i<result.length; i++){
console.log(result[i].Node.Address + ":" + result[i].Service.Port);
}
}
});
axios.post("http://be01.service.consul/api/getUserTiles", {'user':'Max'})
.then(function(response){
if (response.data.has_error) {
console.log("\nRESPONSE HAS ERROR!");
}else {
console.log("\nSUCCESS!");
}
})
.catch(function(err) {
console.log("\nERROR CALLING THE BE SERVICE");
});
運行它我得到以下結果:
root@NGINXLB:~/node8080$ node app.js
DNS SRV query
[ { name: 'agent-be-01.node.dc1.consul',
port: 8080,
priority: 1,
weight: 1 },
{ name: 'agent-be-02.node.dc1.consul',
port: 8081,
priority: 1,
weight: 1 } ]
Consul.health.service query:
10.0.1.5:8080
10.0.1.6:8081
ERROR CALLING THE BE SERVICE
{ Error: getaddrinfo ENOTFOUND be01.service.consul be01.service.consul:80
at errnoException (dns.js:50:10)
at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:92:26)
code: 'ENOTFOUND',
errno: 'ENOTFOUND',
syscall: 'getaddrinfo',
hostname: 'be01.service.consul',
host: 'be01.service.consul',
port: 80,
...
...
正如您所看到的,nodejs客戶端正在調用be服務,但它無法嘗試解析'be01.service.consul'。 此外,它使用端口80而不是Consul DNS接口提供的8080或8081。 我錯過了什么?
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