I’ve enjoyed using Docker for my projects for these reasons:

  • Various projects on my system have varying dependencies (such as Nokogiri), and ensuring all of my projects are always in a working state has been problematic for me in the past.
  • Upgrading or moving to a new computer is always a pain. Getting a new Macbook Pro was always a double-edged sword. For one thing, getting a faster processor and more RAM would be a huge win. But having to re-install everything to get my Rails app working again so I can keep development moving was never fun. Dockerizing my projects has let me avoid this pain.
  • I can run locally against multiple versions of databases like Mongo or Postgres. I can even run a cluster to make sure my configuration for these services are setup right.
  • I can test out different versions of dependencies quickly within a container without worrying about messing up my development environment: just rebuild if the new version doesn’t work.
  • Having explicit versions for production images lets me think about releases as discrete artifacts that can be communicated with my team about. Debugging can be done with a image that can be run in different environments.
  • Getting CI running is fairly trivial with Docker Compose.
  • Once an image has been stabilized, I can use it to speed up CI runs
    • I’ve sped up my personal blog’s deployments from 6 minutes to 1 minute.
  • A production image contains all the correct dependencies I need to run it, including system libraries.
  • Rollbacks for images with changes to system dependencies becomes trivial.
  • Developers can work in different platforms rather than forcing the team to only one OS. This works if the team decides to only develop within containers.
  • Onboarding new developers to the team becomes much simpler. That long README of steps to provision the dev environment becomes:
    • Install Docker
    • Pull repo
    • docker-compose up

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