Assets Serving

Jets handles asset serving by uploading asset files to s3 and serving them directly from s3. This is particularly beneficial for binary assets like images as s3 is better suited for serving them.

By default, these folders are automatically uploaded to s3 as part of the jets deploy command:

Folder Description
public/packs Where app/javascript webpacker assets are compiled to.
public/assets Additional custom assets you might have.
public/images Public images.

Note: Even though public/assets and public/images files are uploaded and served for convenience. It is recommended that you put your files in app/javascript/images and allow webpacker to compile and sha the assets. Files in the public/assets and public/images do not get their sha checksum added to their paths.

By using webpacker, it generates unique file paths each time the file changes. Then you will be able to configure high values for the max-age response header to further improve performance. This article Increasing Application Performance with HTTP Cache Headers covers how cache headers work.

Configure Settings

You can override the setting and configure the folders with the Application Configuration.

Jets.application.configure do
  # ...
  # Default assets settings
  config.assets.folders = %w[packs images assets]
  config.assets.base_url = nil # IE:
  config.assets.max_age = 3600
  config.assets.cache_control = nil # IE: public, max-age=3600 , max_age is a shorter way to set cache_control.

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