title: Permission denied to Docker on Ubuntu
body: <p>Docker is installed on AWS EC2 Ubuntu 16.04 instance as follows: </p>
  
  <p><a href="https://i.stack.imgur.com/BbfXO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BbfXO.png" alt="enter image description here"></a></p>
  
  <p><code>docker info</code> raises a permission denied error:</p>
  
  <blockquote>
    <p>Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get <a href="http://%2Fvar%2Frun%2Fdocker.sock/v1.39/info" rel="nofollow noreferrer">http://%2Fvar%2Frun%2Fdocker.sock/v1.39/info</a>: dial unix /var/run/docker.sock: connect: permission denied</p>
  </blockquote>
  
  <p><code>docker -v</code> shows:  </p>
  
  <pre><code>Docker version 18.09.4, build d14af54
  </code></pre>
  
  <p>uname -a displays:</p>
  
  <pre><code>4.4.0-1072-aws #82-Ubuntu SMP 
  </code></pre>
  
  <p>sudo snap start docker cannot find 'docker'.</p>
  
  <p>What's wrong here? </p>