如何在HAProxy中设置动态变量? [英] How do I set a dynamic variable in HAProxy?

问题描述

是否可以设置一个动态变量，该变量将保存HTTP标头的内容，例如Host/X-Forwarded-Host，是否会在以后的ACL中使用?

Is it possible to set a dynamic variable which will hold the content of HTTP header e.g. Host/X-Forwarded-Host and would be used later in ACLs?

frontend web1
  # ...
  set-var s1(Host)
  acl site1 hdr_end(host) -i %[s1]
  # ...
  use_backend %[s1] if site1

推荐答案

在这里您可以混合使用多种技术.您完全不需要变量即可根据主机地址设置ACL，并使用这些ACL选择后端.就像这样简单:

You have a mix of techniques here. You don't need variables at all to set ACLs based on the host address and select a backend using those ACLs. That would be something simple like:

frontend web1
  # ...
  acl site1 hdr(host) -i example.com
  acl site2 hdr(host) -i example.net
  # ...
  use_backend com if site1
  use_backend net if site2

是您要尝试做的还是要完成更复杂的事情?

Is that all you're trying to do, or are you trying to accomplish something more sophisticated?

更新:以下是根据Host标头选择后端的方法:

UPDATE: Here's how to select a backend based on the Host header:

frontend web1
  # ..
  http-request set-var(req.s1) req.hdr(Host),field(1,:),lower,regsub(\.,_,g)
  use_backend %[var(req.s1)]

backend example_com
  # ..

backend example_net
  # ..

这将设置一个变量，该变量在请求的上下文中有效，使用Host标头的值小写并用下划线替换句点.实际上，您甚至不需要变量:

This sets a variable that is valid in the context of the request, using the value of the Host header lowercased and with periods replaced with underscores. Actually, you don't even need a variable:

frontend web1
  # ..
  use_backend %[req.hdr(Host),field(1,:),lower,regsub(\.,_,g)]

如果找不到与Host标头匹配的后端，

HAproxy将返回503.如果您希望将这样的请求发送到其他地方，则可以设置default_backend(我对此进行了测试，并且至少在1.6.3中有效).

HAproxy will return 503 if a backend that matches the Host header cannot be found. You can set a default_backend if you want such requests to go somewhere else (I tested this and it works in 1.6.3, at least).

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