Bundle fails on install

[AspenJames]

Bundle fails on install

Expected Behavior

bundle or bundle install installs dependencies

Observed Behavior

bundle or bundle install fails with incompatible version

// ♥ bundle
Fetching gem metadata from https://rubygems.org/..........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Bundler could not find compatible versions for gem "bundler":
  In Gemfile:
    rails (= 4.2) was resolved to 4.2.0, which depends on
      bundler (>= 1.3.0, < 2.0)

  Current Bundler version:
    bundler (2.0.1)
This Gemfile requires a different version of Bundler.
Perhaps you need to update Bundler by running `gem install bundler`?

Could not find gem 'bundler (>= 1.3.0, < 2.0)', which is required by gem 'rails (= 4.2)', in
any of the sources.

Cause

Breaking changes in Bundler v2.0

One of the features of Bundler v2.0 is version is "version autoswitching", which you can read about here. This feature requires a Gemfile.lock to be committed into VC, and the Gemfile.lock is currently .gitignored.

Remedy

Check in Gemfile.lock to git. Output below shown on commit c853032, which was immediately prior to Gemfile.lock being removed from git:

[16:05:51] ((HEAD detached at c853032)) model-class-methods-lab-v-000
// ♥ bundle
Fetching gem metadata from https://rubygems.org/..........
======
snip
======
Bundle complete! 12 Gemfile dependencies, 62 gems now installed.

#Staff

[AspenJames]

Important!

This will affect all labs without a Gemfile.lock checked into git wherein a dependency depends on bundler, < 2.0

[heavenlyboheme]

Gemfile.lock is created after running "bundle install" in the terminal.

[AspenJames]

Yes, this is true. What I'm referencing above is a unique failure where a breaking change in Bundler v.2.0 is causing bundle install to fail. A Gemfile.lock file is necessary for the auto-version switching to happen. Since it's not there to begin with, the autoswitching doesn't occur, the dep install fails, and no lockfile is created. We've observed this issue in several students' environments, and while there is a workaround, adding a lockfile is a solution that prevents the failure from ever happening.

Edit: In order to replicate the issue, you will need Bundler v2.0.x installed globally