title: How to setup MongoDB
body: <p>So I have this app:
  <a href="https://github.com/netguru/testblog#netguru-ror-workshop---test-blog" rel="nofollow">github app</a>
   and this is what i get when I try to run it.</p>
  
  <pre><code>Could not connect to a primary node for replica set &lt;Moped::Cluster nodes=[&lt;Moped::Node resolved_address="127.0.0.1:27017"&gt;]&gt;
  </code></pre>
  
  <p>What's the problem?</p>