Jets Assets CloudFront

Jets can create a CloudFront distribution and use it to serve your assets that Jets uploads to s3. Using a CloudFront CDN is recommended.

Though serving assets from S3 is leaps and bounds better than serving them from Lambda, using a CloudFront CDN is even better. CDNs are designed for this very purpose. Your users will have a better experience since the CDN edge locations are closer to them.

To enable:

config/jets/deploy.rb

Jets.deploy.configure do
  config.assets.cloudfront.enable = true
  config.assets.cloudfront.cert.arn = acm_cert_arn(domain: "example.com", region: "us-east-1")
  config.assets.cloudfront.route53.enable = true
  # config.assets.cloudfront.aliases = %w[
  #   assets0.example.com
  #   assets1.example.com
  #   assets2.example.com
  #   assets3.example.com
  # ]
end

Note, when config.assets.cloudfront.aliases is overrides conventional aliases. The conventional aliases would look like this.

config/jets/deploy.rb

Jets.deploy.configure do
  config.assets.cloudfront.aliases = %w[
    demo-dev-assets0.example.com
    demo-dev-assets1.example.com
    demo-dev-assets2.example.com
    demo-dev-assets3.example.com
  ]
end

It is assumed that you do not want the conventional aliases when you explicitly set aliases.

Multiple Hosts

By default, Jets will create multiple hosts from demo-dev-assets0.example.com to demo-dev-assets3.example.com to serve assets. This is catered to the Rails Asset hosts handling. See: ActionView AssetUrlHelper

You can use the %d wildcard in the asset_host to distribute the requests over four hosts.

Expiring CloudFront Caches

On initial creation of the Assets, CloudFront Distribution assets may appear “missing”. This can happen if Route53 does not manage the DNS and Jets cannot automate the DNS record creation. If requests hit CloudFront before you’re done manually setting up the DNS entries on your side, then the CloudFront requests may cache “missing” assets. In this case, you need to expire the caches. Here’s a cheat sheet command.

DIST=E1NL288EXAMPLE
aws cloudfront create-invalidation --distribution-id $DIST --paths '/*'

Related

• CloudFront Assets Distribution: Jets can create a CloudFront distribution and automatically configure it for assets that get precompiled to the public/assets folder by rails assets:precompile.
• CloudFront Lambda Distribution: Jets can create a CloudFront distribution and automatically configure it in front of the deployed controller Lambda Function.
• CloudFront Uploads Distribution: Jets can create a CloudFront distribution and automatically configure it for files like your ActiveStorage uploads.

Reference

The table below covers each setting. Each option is configured with config.OPTION. The config. portion is not shown for conciseness. IE: logger.level vs config.logger.level.

See Full Config Reference