Question

问题：我尝试在临时busybox pod中对ExternalName服务执行cURL，但调用只是挂起。如果我在外部名称上执行相同的cURL，而不是服务名称，则可以使用。

以下是服务名称：

apiVersion: v1
kind: Service
metadata:
  name: google
spec:
  type: ExternalName
  externalName: google.com

我使用kubectl create -f创建服务，然后创建一个临时交互式busybox pod：

kubectl run -i --tty busybox --image=sequenceiq/busybox --restart=Never -- sh

我从中执行以下cURL：

/ # curl google #hangs, have to interrupt
^C
/ # curl google.com

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>302 Moved</TITLE></HEAD><BODY>
<H1>302 Moved</H1>
The document has moved
<A HREF="http://www.google.de/?gfe_rd=cr&amp;ei=SQWDWYXTNZGg8wfFlIGQDw">here</A>.
</BODY></HTML>

所以显而易见的问题是：为什么第一个cURL挂起，但第二个不挂，考虑google只是google.com的CNAME，同样由以下{{1}确认输出（从交互式busybox执行）？

host

以下是挂起cURL命令的详细输出

/ # host google
google.default.svc.cluster.local is an alias for google.com.
google.com has address 172.217.18.174
google.com has IPv6 address 2a00:1450:4001:806::200e
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.

描述服务的输出（不能输出为yaml）：

/ # curl -vvv google
> GET / HTTP/1.1
> User-Agent: curl/7.38.0
> Host: google
> Accept: */*
>

Answer 1

您需要在curl命令中设置主机头

$ curl -I google -H 'Host:google.com'
HTTP/1.1 301 Moved Permanently
Location: http://www.google.com/
Content-Type: text/html; charset=UTF-8
Date: Mon, 30 Dec 2019 03:49:12 GMT
Expires: Wed, 29 Jan 2020 03:49:12 GMT
Cache-Control: public, max-age=2592000
Server: gws
Content-Length: 219
X-XSS-Protection: 0
X-Frame-Options: SAMEORIGIN

Answer 2

您必须添加更多详细网址使用 curl google.default 甚至 curl google.default.svc.cluster.local

它给出结果，但idkw返回404

 # curl google.com
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>

没有名字的空间

/ # curl google
^C

使用名称空间

/ # curl google.default
<!DOCTYPE html>
<html lang=en>
  <meta charset=utf-8>
  <meta name=viewport content="initial-scale=1, minimum-scale=1, width=device-width">
  <title>Error 404 (Not Found)!!1</title>
  <style>
    *{margin:0;padding:0}html,code{font:15px/22px arial,sans-serif}html{background:#fff;color:#222;padding:15px}body{margin:7% auto 0;max-width:390px;min-height:180px;padding:30px 0 15px}* > body{background:url(//www.google.com/images/errors/robot.png) 100% 5px no-repeat;padding-right:205px}p{margin:11px 0 22px;overflow:hidden}ins{color:#777;text-decoration:none}a img{border:0}@media screen and (max-width:772px){body{background:none;margin-top:0;max-width:none;padding-right:0}}#logo{background:url(//www.google.com/images/branding/googlelogo/1x/googlelogo_color_150x54dp.png) no-repeat;margin-left:-5px}@media only screen and (min-resolution:192dpi){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat 0% 0%/100% 100%;-moz-border-image:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) 0}}@media only screen and (-webkit-min-device-pixel-ratio:2){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat;-webkit-background-size:100% 100%}}#logo{display:inline-block;height:54px;width:150px}
  </style>
  <a href=//www.google.com/><span id=logo aria-label=Google></span></a>
  <p><b>404.</b> <ins>That’s an error.</ins>
  <p>The requested URL <code>/</code> was not found on this server.  <ins>That’s all we know.</ins>

Answer 3

悬垂的部分很奇怪。不应该挂起，但返回404。

@santouras是正确的。您需要将主机传递给请求。或者至少在curl发送带有与服务名称相同的Host标头的请求时覆盖它。

基本上，这就是您正在做的事情：

/ # telnet google.com 80
GET / HTTP/1.1
Host: google

HTTP/1.1 404 Not Found
Content-Type: text/html; charset=UTF-8
Referrer-Policy: no-referrer
Content-Length: 1561
Date: Mon, 30 Dec 2019 10:20:07 GMT

<!DOCTYPE html>
<html lang=en>
  <meta charset=utf-8>
  <meta name=viewport content="initial-scale=1, minimum-scale=1, width=device-width">
  <title>Error 404 (Not Found)!!1</title>
  <style>
    *{margin:0;padding:0}html,code{font:15px/22px arial,sans-serif}html{background:#fff;color:#222;padding:15px}body{margin:7% auto 0;max-width:390px;min-height:180px;padding:30px 0 15px}* > body{background:url(//www.google.com/images/errors/robot.png) 100% 5px no-repeat;padding-right:205px}p{margin:11px 0 22px;overflow:hidden}ins{color:#777;text-decoration:none}a img{border:0}@media screen and (max-width:772px){body{background:none;margin-top:0;max-width:none;padding-right:0}}#logo{background:url(//www.google.com/images/branding/googlelogo/1x/googlelogo_color_150x54dp.png) no-repeat;margin-left:-5px}@media only screen and (min-resolution:192dpi){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat 0% 0%/100% 100%;-moz-border-image:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) 0}}@media only screen and (-webkit-min-device-pixel-ratio:2){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat;-webkit-background-size:100% 100%}}#logo{display:inline-block;height:54px;width:150px}
  </style>
  <a href=//www.google.com/><span id=logo aria-label=Google></span></a>
  <p><b>404.</b> <ins>That’s an error.</ins>
  <p>The requested URL <code>/</code> was not found on this server.  <ins>That’s all we know.</ins>

但是您需要这样做：

/ # telnet google.com 80
GET / HTTP/1.1
Host: google.com

HTTP/1.1 301 Moved Permanently
Location: http://www.google.com/
Content-Type: text/html; charset=UTF-8
Date: Mon, 30 Dec 2019 10:21:06 GMT
Expires: Wed, 29 Jan 2020 10:21:06 GMT
Cache-Control: public, max-age=2592000
Server: gws
Content-Length: 219
X-XSS-Protection: 0
X-Frame-Options: SAMEORIGIN

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>

甚至没有Host标头，但没有google。

因此，santouras的请求将起作用，并且这一请求也将起作用：

curl -H "Host:" google

从Kubernetes Pod到ExternalName服务的cURL挂起

3 个答案: