title: Docker container running but can't view in browser
body: <p>I'm new with <strong>Docker</strong> and i'm trying to run <strong>ruby</strong> app inside a docker.
  So i created a ruby app that work and run fine, I also created a image and a docker that when i run and build them it's running just fine.
  After I running the docker it's shown like it's running without problems, i get an IP from <code>docker inspect</code> and the port shown at <code>docker ps -a</code>  as 3000. </p>
  
  <p>when i open the IP:port at the browser I can't see nothing. </p>
  
  <p><strong>here is my docker file:</strong></p>
  
  <pre><code>&gt; FROM ruby:latest 
  &gt; 
  &gt; # Set the working directory to /app WORKDIR /app
  &gt; 
  &gt; # Copy the current directory contents into the container at /app ADD . /app
  &gt; 
  &gt; RUN echo 'debconf debconf/frontend select Noninteractive' |
  &gt; debconf-set-selections RUN apt-get update \
  &gt;     &amp;&amp; DEBIAN_FRONTEND=Noninteractive   apt-get install -y \
  &gt;         sqlite3 \
  &gt;         thin \
  &gt;         nodejs \
  &gt;         apt-utils \
  &gt;     &amp;&amp; bundle install 
  &gt; # --no-install-recommends apt-utils sudo
  &gt; 
  &gt; 
  &gt; #RUN sudo -H cp config/initializers/rack_attack.rb config/initializers/rack_attack.rb
  &gt; 
  &gt; # Install any needed packages specified in requirements.txt
  &gt; # RUN pip install -r requirements.txt 
  &gt; EXPOSE 3000
  &gt; 
  &gt; CMD ["bundle",  "exec", "rails", "server"]
  </code></pre>
  
  <p><strong>Edit:</strong></p>
  
  <p>I tried also with '<strong>Expose 3000</strong>' and also run with '-p' flag.<br>
  When i run 'docker ps -a' the <strong>ports</strong> are: '<strong>0.0.0.0:32768->3000/tcp</strong>'.<br>
  For 'docker inspect' i get the <strong>IP</strong>: '172.17.0.2'</p>
  
  <p>but when i go to '<a href="http://172.17.0.2:3000/" rel="nofollow noreferrer">http://172.17.0.2:3000/</a>' in the browser i see nothing.</p>
  
  <p><strong>NEW EDIT</strong></p>
  
  <blockquote>
    <p>I discover that the docker is running as tcp6 (IPv6), how can i
    configure it to be tcp? .</p>
  </blockquote>