I have a website using Jekyll with Github Pages. After previously messing about with versions and RVM on another computer, on this one I opted to stick with just one version of Ruby and per-project environments using bundler.
I have a pretty simple Gemfile:
[$]> cat Gemfile
source 'https://rubygems.org'
gem 'github-pages'
and bundler config:
[$]> cat .bundle/config
---
BUNDLE_PATH: env
BUNDLE_DISABLE_SHARED_GEMS: '1'
When I run any command (jekyll, gem, irb) through bundle exec, I get a dependency error:
[$]> bundle exec jekyll
Could not find RedCloth-4.2.9 in any of the sources
Run `bundle install` to install missing gems.
However, the bundle is already installed:
[$]> bundle install
Using RedCloth 4.2.9
Using i18n 0.6.11
Using json 1.8.1
[snip]
Using github-pages 29
Using bundler 1.7.7
Your bundle is complete!
It was installed into ./env
I'm at a bit of a loss as to how bundler can think the gems are installed when using one subcommand, but think they're missing when using another.
[$]> which ruby
/usr/local/bin/ruby
[$]> which bundler
/usr/local/bin/bundler
[$]> ruby --version
ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14]
[$]> bundler --version
Bundler version 1.7.7
After deleting the env directory and reinstalling, I noticed it created subdirectories for two Ruby versions - 2.1.0 and 2.2.0. The latter was my current version of Ruby, but the directory was empty (all the gems were installed into the env/ruby/2.1.0/gems directory). This, combined with Oliver's answer about rbenv, got me thinking about mismatched versions.
I reinstalled bundler with a simple gem install bundler, reran bundle install, and all is good.
It seems in general the answer is to sort out issues with bundler installing for a different version of Ruby than you're actually using. It seems strange to me it would use one thing for bundle install and another for bundle exec, but *shrug* whatever.