Saturday, 19 December 2020

Upgrading to the Heroku-20 buildpack and Bundler 2

I figured it's about time to start moving my various running applications and kit to Ubuntu 20, now there is a new LTS version and well before v18 totally dies. I know I'm late to this party, but I've been busy.

Today I updated an application hosted on Heroku and since it wasn't 100% smooth thought I'd capture my steps, both for myself in future and anyone else who finds it useful.

The tech

  • Ruby on Rails application
  • Ruby 2.5.1 (Ubuntu 18 default version)
  • Bundler 1.17.3
  • Heroku on buildpack 18
  • Codeship for automated testing and deployment

The process

On Heroku, go to the app page then its settings. On this page you can change the stack via the big red "upgrade" button. This requires a redeploy of the application.

Back at the app, I updated by ruby version (.ruby-version file for me), installed bundler and ran bundle update --bundler to upgrade from Bundler to Bundler2. This provoked some other minor config changes, all in this diff.

Then Codeship broke. As in, it was totally down. Sigh. When this came back, the build was not working, giving me a deadlock error when running bundle install. This gotcha took a while to fix (hence writing this post). In the end, all I had to do was add gem update --system to the build setup commands before gem install bundler.

And voila, we're in the modern world and everything works.

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