title: missing environmental variables nginx container
body: <p>I am trying to evaluate cookiecutter-django, so far its a great tool to start a project. everything is going smooth except when I tried to use docker with certbot, i'm having this error.</p>
  
  <pre><code>nginx_1         | 2016/06/15 07:55:36 [emerg] 1#1: invalid port in upstream "___LETSENCRYPT_IP___:___LETSENCRYPT_PORT___" in /etc/nginx/nginx.conf:42
  </code></pre>
  
  <p>the start.sh contains</p>
  
  <pre><code>sed -i "s/___LETSENCRYPT_IP___/$LETSENCRYPT_PORT_80_TCP_ADDR/g" /etc/nginx/nginx.conf
  sed -i "s/___LETSENCRYPT_PORT___/$LETSENCRYPT_PORT_80_TCP_PORT/g" /etc/nginx/nginx.conf
  </code></pre>
  
  <p>I'm not a guru here, but I can see that the script is referencing with environmental variables, but when i tried to inspect the enviromental variables in nginx container, I didn't see anything related to letsencrypt.</p>
  
  <pre><code>[root@localhost]# docker-compose run nginx bash
  Starting tbpcsuite_certbot_1
  Starting tbpcsuite_postgres_1
  Starting tbpcsuite_redis_1
  Starting tbpcsuite_django_1
  root@b7d12c245b86:/# set
  BASH=/bin/bash
  BASHOPTS=checkwinsize:cmdhist:complete_fullquote:expand_aliases:extquote:force_fignore:hostcomplete:interactive_comments:progcomp:promptvars:sourcepath
  BASH_ALIASES=()
  BASH_ARGC=()
  BASH_ARGV=()
  BASH_CMDS=()
  BASH_LINENO=()
  BASH_SOURCE=()
  BASH_VERSINFO=([0]="4" [1]="3" [2]="30" [3]="1" [4]="release" [5]="x86_64-pc-linux-gnu")
  BASH_VERSION='4.3.30(1)-release'
  COLUMNS=197
  DIRSTACK=()
  EUID=0
  GROUPS=()
  HISTFILE=/root/.bash_history
  HISTFILESIZE=500
  HISTSIZE=500
  HOME=/root
  HOSTNAME=b7d12c245b86
  HOSTTYPE=x86_64
  IFS=$' \t\n'
  LINES=73
  MACHTYPE=x86_64-pc-linux-gnu
  MAILCHECK=60
  MY_DOMAIN_NAME=www.192.168.33.10.xip.io
  NGINX_VERSION=1.11.1-1~jessie
  OPTERR=1
  OPTIND=1
  OSTYPE=linux-gnu
  PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
  PIPESTATUS=([0]="1")
  PPID=0
  PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
  PS2='&gt; '
  PS4='+ '
  PWD=/
  SHELL=/bin/bash
  SHELLOPTS=braceexpand:emacs:hashall:histexpand:history:interactive-comments:monitor
  SHLVL=1
  TERM=xterm
  UID=0
  _=']'
  </code></pre>
  
  <p>I'm lost, any guidance I will appreciate.</p>
  
  <p>Thanks,</p>