Docker Network Nginx Resolver

Question

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.

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)

Can someone explain how to configure nginx resolver with docker networks.

Comments

Check your DNS nameserver

Answer 1

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

The reason for your problem could be one of these

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

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)

1. 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 httpblock. That had me scratching my head for a long time...

Comments

Hey, I tried your solution, it's working for me. I am running nginx as a docker container inside Vagrant box. I cat /etc/resolv.conf .

nameserver 127.0.0.11

options ndots:0

It will be great if you help me

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Can you please explain the issue you're facing in detail?

Answer 2

I had the exact same error. Funny story, I used the wrong IP address of the nameserver.