title: What is the core file in Docker and can I remove it?
body: <p>I got No space left on device warning at my vm and I found that the folder <code>/var/lib/docker/overlay2</code> has about 10Gb files. 
  I found that there are many large core file inside 
  <code>/var/lib/docker/overlay2/84af149f81834654b47904e72c5c3760b8bc874c90b355628927ffca3bc17ce5/merged/home/app/app</code>.</p>
  
  <pre><code>1.4G    core.20715
  1.1G    core.20746
  709M    core.24489
  384M    core.14116
  379M    core.26810
  364M    core.20730
  258M    core.32643
  107M    node_modules
  69M core.20722
  100K    package-lock.json
  </code></pre>
  
  <p>What is the function of the core file, can I remove those files and how to prevent generate those files?</p>