Docker – Why isn’t ifconfig available in Ubuntu Docker container

Docker might support networking in the future. But for now you can you Pipework to manage Docker network like this (Host only).

sudo pipework br1 $(docker run -d -i -t elasticsearch:0.90.5) 192.168.2.1/24
sudo ip addr add 192.168.2.254/24 dev br1

But if you want it to be public IP address x.x.x.x (ubiquitous):

pipework eth0 $(docker run -d -i -t elasticsearch:0.90.5) x.x.x.x

From the official Nginx docker file:

Using environment variables in nginx configuration:

Out-of-the-box, Nginx doesn't support using environment variables inside most configuration blocks.

But envsubst may be used as a workaround if you need to generate your nginx configuration dynamically before nginx starts.

Here is an example using docker-compose.yml:

image: nginx
volumes:
 - ./mysite.template:/etc/nginx/conf.d/mysite.template
ports:
 - "8080:80"
environment:
 - NGINX_HOST=foobar.com
 - NGINX_PORT=80
command: /bin/bash -c "envsubst < /etc/nginx/conf.d/mysite.template > /etc/nginx/conf.d/default.conf && nginx -g 'daemon off;'" 

The mysite.template file may then contain variable references like this :

listen ${NGINX_PORT};

Update:

But you know this caused to its Nginx variables like this:

proxy_set_header        X-Forwarded-Host $host;

damaged to:

proxy_set_header        X-Forwarded-Host ;

So, to prevent that, i use this trick:

I have a script to run Nginx, that used on the docker-compose file as command option for Nginx server, i named it run_nginx.sh:

#!/usr/bin/env bash
export DOLLAR='$'
envsubst < nginx.conf.template > /etc/nginx/nginx.conf
nginx -g "daemon off;"

And because of defined new DOLLAR variable on run_nginx.sh script, now content of my nginx.conf.template file for Nginx itself variable is like this:

proxy_set_header        X-Forwarded-Host ${DOLLAR}host;

And for my defined variable is like this:

server_name  ${WEB_DOMAIN} www.${WEB_DOMAIN};

Also here, there is my real use case for that.