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Docker Network Nginx Resolver

I am trying to get rid of deprecated Docker links in my configuration. What's left is getting rid of those Bad Gateway nginx reverse proxy errors when I recreated a container.

Note: I am using Docker networks in bridge mode. (docker network create nettest)

I am using the following configuration snippet inside nginx:

location / {       resolver 127.0.0.1 valid=30s;       set $backend "http://confluence:8090";       proxy_pass $backend; 
  1. I started a container with hostname confluence on my Docker network with name nettest.
  2. Then I started the nginx container on network nettest.
  3. I can ping confluence from inside the nginx container
  4. confluence is listed inside the nginx container's /etc/hosts file
  5. nginx log says send() failed (111: Connection refused) while resolving, resolver: 127.0.0.1:53
  6. I tried the docker network default dns resolver 127.0.0.11 from /etc/resol.conf
  7. nginx log says confluence could not be resolved (3: Host not found)

Anybody knows how to configure nginx resolver with Docker Networks or an alternative on how to force Nginx to correctly resolve the Docker network hostname?

like image 832
blacklabelops Avatar asked Mar 02 '16 10:03

blacklabelops


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1 Answers

First off, you should be using the Docker embedded DNS server at 127.0.0.11.

Your problem could be caused by 1 of the following:

  1. nginx is trying to use IPv6 (AAAA record) for the DNS queries.

    See https://stackoverflow.com/a/35516395/1529493 for the solution.

    Basically something like:

    http {     resolver 127.0.0.11 ipv6=off; } 

    This is probably no longer a problem with Docker 1.11:

    Fix to not forward docker domain IPv6 queries to external servers (#21396)

  2. Take care that you don't accidentally override the resolver configuration directive. In my case I had in the server block resolver 8.8.8.8 8.8.4.4; from Mozilla's SSL Configuration Generator, which was overriding the resolver 127.0.0.11; in the http block. That had me scratching my head for a long time...

like image 77
Teoh Han Hui Avatar answered Sep 23 '22 03:09

Teoh Han Hui