title: Running gulp in `docker-compose build`
body: <p>I am attempting to include a gulp build process as part of a <code>docker-compose</code> build process.</p>
  
  <h3>Dockerfile:</h3>
  
  <pre><code>FROM python:3.5.1-onbuild
  
  RUN apt-get update
  RUN apt-get install -y nodejs npm
  COPY /app/package.json /usr/src/app/app/
  WORKDIR /usr/src/app/app
  RUN npm install --only=production
  RUN npm install --global gulp-cli
  RUN gulp
  
  WORKDIR /
  EXPOSE 8080
  RUN python3 setup.py install
  CMD python3 manage.py ${MODE}
  </code></pre>
  
  <h3>docker-compose.yml:</h3>
  
  <pre><code>build: ${REPO}
  environment:
      - CONFIG_DIR=/config
      - MODE=production
  </code></pre>
  
  <p>Each time I hit <code>RUN gulp</code>, I get the error <code>/usr/bin/env: node: No such file or directory</code>.</p>
  
  <p>What am I missing?</p>