title: Running docker image does not work
body: <p>I'm new to Docker, and I am doing the Node.js tutorial for Docker. I'm stuck at exactly this step: <a href="http://docs.docker.io/en/latest/examples/nodejs_web_app/#building-your-image" rel="nofollow noreferrer">http://docs.docker.io/en/latest/examples/nodejs_web_app/#building-your-image</a></p>
  
  <p>I have executed this:</p>
  
  <pre><code>$ docker build -t user/centos-node-hello .
  ...
  Successfully built c04aea889b03
  </code></pre>
  
  <p>and it built successfully.</p>
  
  <pre><code>$ docker images
  REPOSITORY                  TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
  user/centos-node-hello   latest              c04aea889b03        23 minutes ago      667.9 MB
  ubuntu                      13.10               9f676bd305a4        9 weeks ago         178 MB
  ubuntu                      saucy               9f676bd305a4        9 weeks ago         178 MB
  ubuntu                      raring              eb601b8965b8        9 weeks ago         166.5 MB
  ubuntu                      13.04               eb601b8965b8        9 weeks ago         166.5 MB
  ubuntu                      12.10               5ac751e8d623        9 weeks ago         161 MB
  ubuntu                      quantal             5ac751e8d623        9 weeks ago         161 MB
  ubuntu                      10.04               9cc9ea5ea540        9 weeks ago         180.8 MB
  ubuntu                      lucid               9cc9ea5ea540        9 weeks ago         180.8 MB
  ubuntu                      12.04               9cd978db300e        9 weeks ago         204.4 MB
  ubuntu                      latest              9cd978db300e        9 weeks ago         204.4 MB
  ubuntu                      precise             9cd978db300e        9 weeks ago         204.4 MB
  busybox                     latest              769b9341d937        9 weeks ago         2.489 MB
  centos                      6.4                 539c0211cd76        12 months ago       300.6 MB
  </code></pre>
  
  <p>Now I try to run the image:</p>
  
  <pre><code>$ docker run -p 49160:8080 -d user/centos-node-hello
  995bfeef4edd723027480fdb43f097e2ba6a97b8fb1d2e9ec679dc1247f68a84
  </code></pre>
  
  <p>But if I check the processes, the instance is not running.</p>
  
  <pre><code>$ docker ps
  CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS             PORTS  
  </code></pre>
  
  <p>Any ideas? Thank you.</p>