How should I link to other Docker containers?

[johnjelinek]

I can link to other containers, but I cannot reference the environment variables in my sites-enabled/ conf files. Do you know of a good way to reference your linked containers?

[johnjelinek]

I think a commit like this could help: phusion/passenger-docker@8aff974. It provides access to main.d/ where you can put env variables.

[johnjelinek]

Off-topic: Am I correct in assuming that the only way to restart nginx to read new conf files is by recreating the container?

$ docker rm -f nginx; docker run --name nginx -d -p 80:80 -p 8080:8080 -v /home/admin/sites-enabled:/etc/nginx/sites-enabled -v /home/admin/nginx-logs:/var/log/nginx dockerfile/nginx

[DaleWebb]

Have you tried attaching to the container and running the nginx reload command?

[johnjelinek]

Yes, the issue is that nginx needs Perl support to read environment
variables of linked containers. See here:
docker-library/nginx#1.
On Jul 14, 2014 5:10 AM, "Dale Webb" [email protected] wrote:

Have you tried attaching to the container and running the nginx reload
command?

—
Reply to this email directly or view it on GitHub
#3 (comment).

[eugene-dounar]

You can access linked containers by hostname. See the paragraph about generated /etc/hosts in https://docs.docker.com/userguide/dockerlinks/

[dimroc]

Eugene's approach is indeed better. Here's an example based on eugene's link (https://docs.docker.com/userguide/dockerlinks/) with Vagrant:

config.vm.provision "docker", images: ["dockerfile/nginx", "dockerfile/elasticsearch"] do |d|
    # docker run -d -p 127.0.0.1:9200:9200 -p 127.0.0.1:9300:9300 dockerfile/elasticsearch # only allows localhost connections w 127.0.0.1
    d.run "dockerfile/elasticsearch", daemonize: true, args: "--name es -p 127.0.0.1:9200:9200 -p 127.0.0.1:9300:9300"

    # docker run -d -p 80:80 dockerfile/nginx
    d.run "dockerfile/nginx", daemonize: true, args: "--name nginx --link es:es -p 80:80 -p 443:443 -v /etc/nginx/sites-enabled:/etc/nginx/sites-enabled -v /var/log/nginx:/var/log/nginx"
  end

The configuration in sites-enabled:

server {
  listen                80 default_server;

  access_log            /var/log/nginx/elasticsearch.access.log;
  error_log            /var/log/nginx/elasticsearch.error.log;

  location / {
    proxy_pass http://es:9200;
    proxy_read_timeout 90;
  }
}

Linked docker parent containers automatically get the child's ip populated in the /etc/hosts file. Notice the http://es:9200, this is because es is in the /etc/hosts file.

[karabijavad]

pretty sure its at /etc/nginx/conf.d/ that the configuration needs to go