使用rbenv+Bundler启动Unicorn时无法加载指定Gem的问题

I’ve run into this exact frustration before with rbenv and Bundler—let’s break down the most likely causes and fixes for why your gems aren’t loading despite bundle show confirming they’re installed:

1. Unicorn might be using the wrong Ruby version (not your rbenv 1.9.3-p484) #

Even if you’ve set global/local rbenv versions, sometimes the unicorn binary being executed isn’t the one from your rbenv shims. Here’s how to verify and fix this:

• Run which unicorn—it should point to something like ~/.rbenv/shims/unicorn. If it shows /usr/bin/unicorn or another system-level path, that’s the issue.
• Fix: Ensure ~/.rbenv/shims is at the top of your PATH variable. Check with echo $PATH—if rbenv’s shims aren’t first, update your shell config (.bashrc, .zshrc) to add export PATH="$HOME/.rbenv/shims:$PATH" and restart your terminal. Also, double-check you’re running commands from your project root (rbenv’s local version only applies to that directory).

2. Your GEM_HOME override is conflicting with Bundler’s isolated paths #

Bundler creates a project-specific gem set (usually in vendor/bundle or a rbenv-managed directory) to keep dependencies isolated. Manually setting GEM_HOME tells Ruby to look for gems in a global path instead of Bundler’s dedicated folder.

• Check if GEM_HOME is set: Run echo $GEM_HOME. If it returns a path, that’s almost certainly interfering.
• Fix: Temporarily unset it for the current session with unset GEM_HOME, then try bundle exec unicorn again. If this works, remove the export GEM_HOME=... line from your shell config—rbenv + Bundler handle gem paths automatically, so you don’t need this manual setup.

3. Your Gemfile.lock is out of sync or from a different environment #

If you copied Gemfile.lock from another machine or environment, it might reference gem versions or paths that don’t match your local 1.9.3-p484 setup.

• Fix: Delete Gemfile.lock, then run bundle install to generate a fresh lock file tailored to your current environment. Also, double-check that haml-contrib and sinatra-activerecord are explicitly listed in your Gemfile—Bundler only loads gems defined there, even if they’re installed locally.

4. rbenv’s shims haven’t been updated for new gems #

Sometimes rbenv doesn’t refresh its shims after installing gems via Bundler, leading to outdated references.

• Fix: Run rbenv rehash in your project directory, then try starting Unicorn again.

5. Permissions issues with Bundler’s gem directory #

If your user doesn’t have read access to the gem files (e.g., they’re owned by root or another user), Bundler will fail to load them without clear feedback.

• Check permissions: Run ls -la $(bundle show haml-contrib) to confirm your user has access.
• Fix: If permissions are incorrect, run sudo chown -R $USER:$USER ~/.rbenv (or the path to your Bundler gem directory) to take ownership of the files.

内容的提问来源于stack exchange，提问作者Danila Ladner