Should Gemfile.Lock Be Committed to Source Control on Windows

Should Gemfile.lock be included in .gitignore?

Simple answer in the year 2021:
Gemfile.lock should be in the version control also for Rubygems. The accepted answer is now 11 years old.

Some reasoning here (cherry-picked from comments):

@josevalim https://github.com/heartcombo/devise/pull/3147#issuecomment-52193788

The Gemfile.lock should stay in the repository because contributors and developers should be able to fork the project and run it using versions that are guaranteed to work.

@rafaelfranca https://github.com/rails/rails/pull/18951#issuecomment-74888396

I don't think it is a good idea to ignore the lock file even for plugins.
This mean that a "git clone; bundle; rake test" sequence is not guarantee to be passing because one of yours dozens of dependencies were upgraded and made your code break. Also, as @chancancode said, it make a lot harder to bisect.

Also Rails has Gemfile.lock in git:

https://github.com/rails/rails/commit/0ad6d27643057f2eccfe8351409a75a6d1bbb9d0

Gemfile.lock not checked in - Heroku

Found the answer at - http://www.unityisplural.com/2010/11/hobo-finally.html

Why won't Heroku accept my Gemfile.lock in Windows?

Like matt commented above:

The problem is that Bundler creates different Gemfile.locks for Windows. The only solution is to create and commit the lock file on a *NIX system.

I would suggest to create a virtual machine running e.g. Ubuntu – maybe using Virtual Box. You can even get ready-to-use virtual machines – for example here.

Cannot push to Heroku (gemfile.lock issue)

The answer was deceptively simple (of course):

git push staging staging:master

The issue was that I was on the staging branch and needed to update my Heroku staging server's master branch.

Shame on me for overlooking something so obvious!
... and shame on Heroku's decidedly unhelpful output.

Bundler: You are trying to install in deployment mode after changing your Gemfile

The error message you're getting regarding Gemfile.lock may be because your Gemfile and Gemfile.lock don't agree with each other. It sounds like you've changed something in your Gemfile since you last ran bundle install (or update). When you bundle install, it updates your Gemfile.lock with any changes you've made to Gemfile.

Make sure you run bundle install locally, and check-in to source control your newly updated Gemfile.lock after that. Then try deploying.

Edit: As recognised in the comments, a conditional in the Gemfile resulted in a valid Gemfile.lock on one platform, invalid on another. Providing a :platform flag for these platform-dependent gems in the Gemfile should solve the asymmetry.