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Bastien974
Asked: 2015-04-08 07:36:10 +0800 CST

Force HAProxy to lookup DNS for backend server

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I have haproxy 1.5.8, it proxies some requests (based on the path) to a third-party we have no control over.

Since the IP of backend server is resolved once at startup, it breaks if the IP change.

If there a workaround for that ? In nginx it's possible to declare an internal variable and have it cached for X seconds. I didn't found a similar solution for HAProxy.

domain-name-system

2 Answers

  1. With the recent release of HAProxy 1.6 there is a solution to your problem. You can now define resolvers and associate these to your backend. IP resolution will then be done at runtime.

    resolvers dns
  nameserver public-0  xx.xx.xx.xx:53
  hold valid 1s

frontend http
  bind *:8000
  default_backend site-backend

backend site-backend
  balance leastconn
  server site sub.example.com:80 resolvers dns check inter 1000

    StackOverflow discussing this

    Link to the corresponding documentation

    • 27

  2. Unfortunately, it seems like this is still a work in progress.

    Have you considered using a separate nginx proxy? So that you forward requests for that backend to an nginx instance, which then does DNS resolution and forwards the request? Not ideak, but may work in a lower traffic environment.

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