title: Why is docker build taking so long to run?
body: <p>I'm running docker build and it's taking an awfully long time to run. Infact, it doesn't complete and I have to CTRL + C to quit.</p>
  
  <p>Last night things were working fine. When I returned to the computer and tried to rebuild it started acting strange.</p>
  
  <p>Here's my command:</p>
  
  <pre><code>docker build -t mywebsite/backend .
  </code></pre>
  
  <p>When I ran it I noticed this:</p>
  
  <pre><code>Sending build context to Docker daemon 213.8 MB
  Step 1 : FROM ubuntu:14.04
  </code></pre>
  
  <p>I have no idea why the file size was 213.8. The only directory that is large is <code>node_modules</code> and that contains <code>.dockerignore</code> so it shouldn't be touching that directory.</p>
  
  <p>After that ran I had an error, so I fixed it and reran:</p>
  
  <pre><code>docker build -t mywebsite/backend .
  </code></pre>
  
  <p>This time it just hung. And continues to do so.</p>
  
  <p>Here is my <code>Dockerfile</code></p>
  
  <pre><code>FROM ubuntu:14.04
  
  # Set env. variables
  ENV DEBIAN_FRONTEND noninteractive
  
  # Application
  ENV APP_PORT 3000
  
  # Amazon
  ENV AMAZON_BUCKET mybucket
  ENV AMAZON_ACCESS_KEY_ID mykey
  ENV AMAZON_SECRET_ACCESS_KEY mytoken
  
  # Set working directory
  WORKDIR ~/vms
  
  # Install NodeJS
  RUN apt-get update; apt-get install -y curl;
  RUN curl -sL https://deb.nodesource.com/setup_4.x | sudo -E bash -
  RUN apt-get install -y nodejs
  
  # Install node dependencies
  ADD package.json package.json
  RUN npm install --production
  
  # Copy files to the container
  ADD src src
  
  EXPOSE 3000
  
  # Start application
  RUN npm start
  </code></pre>
  
  <p>The directory I am in when I run the command is the one that contains the Dockerfile:</p>
  
  <pre><code>- backend
    - node_modules
    - src
      - config
      - routes
      - views
      index.js
    Dockerfile
    package.json
  </code></pre>
  
  <p>I'm running docker on Ubuntu 14.04</p>