求助：使用Rails 5.1和Ruby 2.4时生产环境无法加载Assets

Hey there! Let’s work through this asset loading problem you’re hitting—local works great, but production’s failing to load assets? Super common scenario, but we can nail it down with a few checks:

1. First, Verify Asset Precompilation #

Production Rails doesn’t compile assets on the fly like development mode does, so this is the first stop:

• Did you run the precompile command before deploying? Run RAILS_ENV=production rails assets:precompile locally (or on your production server) and check if the public/assets directory populates with hashed files (like application-abc123.css).
• If you’re using a deployment tool like Capistrano, double-check that your deploy script includes the precompile step—some setups skip it by default if there are no asset changes, which can cause issues if you modified assets but the tool didn’t detect it.

2. Check Your config/environments/production.rb Settings #

A misconfigured production env is often the culprit:

• Ensure config.assets.compile is set correctly: The default is false (which requires full precompilation). If you’re testing temporarily, you can set it to true (but don’t leave it this way long-term—it hurts performance).
• Confirm config.public_file_server.enabled = true—this lets Rails serve static assets if your web server isn’t handling them.
• Make sure config.assets.digest = true—this adds unique hashes to asset filenames, preventing browser caching of old versions.

3. Web Server Configuration (Nginx/Apache) #

If you’re using a reverse proxy like Nginx, it needs to know where to find your assets:

• For Nginx, add a location block pointing to your app’s public/assets folder (adjust the path to match your server setup):

  location /assets/ {
      root /var/www/your-app-name/public;
      expires 1y;
      add_header Cache-Control public;
  }
  

• Check file permissions: The public/assets directory and its files should be readable by your web server user (usually www-data for Nginx/Apache). Run chmod -R 755 public/assets if needed.
• If you’re using Puma/Unicorn directly without a web server, ensure config.public_file_server.enabled = true in production.rb to let Rails serve static files.

4. Cache & CDN Gotchas #

Caching can trick you into thinking assets aren’t loading when they’re just stuck in a cache:

• Test in incognito mode to rule out browser cache issues, or force a hard refresh (Ctrl+F5 on Windows/Linux, Cmd+Shift+R on Mac).
• If you’re using a CDN, flush its cache—old asset paths might be cached there even after you’ve updated assets.

5. Ensure You’re Using Rails Asset Helpers #

Hardcoded paths are a common mistake:

• Always use Rails’ built-in helpers like <%= stylesheet_link_tag 'application' %>, <%= javascript_include_tag 'application' %>, or asset_path('image.png') instead of writing paths like /stylesheets/application.css directly.
• These helpers automatically use the hashed asset paths generated during precompilation, which avoids mismatches.

6. Gem & Dependency Checks #

Make sure your production environment has all the gems needed to compile assets:

• Double-check your Gemfile to ensure assets-related gems like sass-rails, uglifier, and coffee-rails aren’t restricted to the :development group—they need to be available in production.
• Run bundle install --without development test on your production server to ensure all production gems are installed correctly.

If you’ve worked through all these steps and still see issues, take a look at your log/production.log for specific error messages (like "File not found" for a particular asset)—that’ll help narrow down the problem further!

内容的提问来源于stack exchange，提问作者Anson GN