Docker Compose networking: hostnames in nginx not resolving - networking

Question

I've attempted to migrate my stack to use version 2 docker-compose.yml and have run into a problem with network hostnames not being resolved by nginx.
My stack involves an nginx reverse proxy (on debian:wheezy) that serves secure content via several other software components of which I won't go into detail (see config below).
In the version 1 yaml, I used environment variables from docker links alongside with LUA script to insert them into the nginx.conf (using nginx-extras). This worked perfectly as a reverse proxy in front of the docker containers.
In the version 2 yaml I am using the hostnames as generated by docker networking. I am able to successfully ping these hostnames from within the container, however nginx is unable to resolve them.
2016/05/04 01:23:44 [error] 5#0: *3 no resolver defined to resolve ui, client: 10.0.2.2, server: , request: "GET / HTTP/1.1", host: "localhost"
Here is my current config:
docker-compose.yml:
version: '2'
services:
# back-end
api:
build: .
depends_on:
- db
- redis
- worker
environment:
RAILS_ENV: development
ports:
- "3000:3000"
volumes:
- ./:/mmaps
- /var/log/mmaps/api:/mmaps/log
volumes_from:
- apidata
command: sh -c 'rm -rf /mmaps/tmp/pids/server.pid; rails server thin -b 0.0.0.0 -p 3000'
# background process workers
worker:
build: .
environment:
RAILS_ENV: development
QUEUE: "*"
TERM_CHILD: "1"
volumes:
- ./:/mmaps
- /var/log/mmaps/worker:/mmaps/log
volumes_from:
- apidata
command: rake resque:work
# front-end
ui:
image: magiandev/mmaps-ui:develop
depends_on:
- api
ports:
- "8080:80"
volumes:
- /var/log/mmaps/ui:/var/log/nginx
# database
db:
image: mysql:5.7
environment:
MYSQL_ROOT_PASSWORD: pewpewpew
volumes_from:
- mysqldata
volumes:
- /var/log/mmaps/db:/var/log/mysql
# key store
redis:
image: redis:2.8.13
user: root
command: ["redis-server", "--appendonly yes"]
volumes_from:
- redisdata
volumes:
- /var/log/mmaps/redis:/var/log/redis
# websocket server
monitor:
image: magiandev/mmaps-monitor:develop
depends_on:
- api
environment:
NODE_ENV: development
ports:
- "8888:8888"
# media server
media:
image: nginx:1.7.1
volumes_from:
- apidata
ports:
- "3080:80"
volumes:
- ./docker/media/nginx.conf:/etc/nginx/nginx.conf:ro
- /srv/mmaps/public:/usr/local/nginx/html:ro
- /var/log/mmaps/mediapool:/usr/local/nginx/logs
# reverse proxy
proxy:
build: docker/proxy
ports:
- "80:80"
- "443:443"
volumes:
- /var/log/mmaps/proxy:/var/log/nginx
apidata:
image: busybox:ubuntu-14.04
volumes:
- /srv/mmaps/public:/mmaps/public
command: echo api data
mysqldata:
image: busybox:ubuntu-14.04
volumes:
- /srv/mmaps/db:/var/lib/mysql
command: echo mysql data
redisdata:
image: busybox:ubuntu-14.04
volumes:
- /srv/mmaps/redis:/data
command: echo redis data
# master data
# convenience container for backups
data:
image: busybox:ubuntu-14.04
volumes_from:
- apidata
- mysqldata
- redisdata
command: echo mmaps data
nginx.conf
worker_processes 1;
events {
worker_connections 1024;
}
http {
# permanent redirect to https
server {
listen 80;
rewrite ^ https://$host$request_uri? permanent;
}
server {
listen 443 ssl;
ssl on;
ssl_certificate /etc/nginx/ssl/server.crt;
ssl_certificate_key /etc/nginx/ssl/server.key;
location / {
proxy_pass http://ui:80$request_uri;
}
location /monitor/ {
proxy_pass http://monitor:8888$request_uri;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
location /api/ {
client_max_body_size 0;
proxy_pass http://api:3000$request_uri;
}
location /files/ {
client_max_body_size 0;
proxy_pass http://media:80$request_uri;
}
location /mediapool/ {
proxy_pass http://media:80$request_uri;
add_header X-Upstream $upstream_addr;
if ($request_uri ~ "^.*\/(.*\..*)\?download=true.*$"){
set $fname $1;
add_header Content-Disposition 'attachment; filename="$fname"';
}
proxy_pass_request_headers on;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /var/www;
}
}
}
# stay in the foreground so Docker has a process to track
daemon off;
After some reading I have tried to use 'dnsmasq' and set resolver 127.0.0.1 within the nginx.conf but I cannot get this to work:
2016/05/04 01:54:26 [error] 6#0: recv() failed (111: Connection refused) while resolving, resolver: 127.0.0.1:53
Is there a better way to configure nginx to proxy pass to my containers that works with V2?

Answer 1

You can rename your containers and resolving by names.