Action Controller Etag With Template Digest

When our views change, they should bubble up into HTTP cache freshness and bust browser caches. So the template digest for the current action is automatically included in the ETag.

Enabled by default for apps that use Action View. Disable by setting

config.action_controller.etag_with_template_digest = false

Override the template to digest by passing :template to fresh_when and stale? calls. For example:

# We're going to render widgets/show, not posts/show
fresh_when @post, template: 'widgets/show'

# We're not going to render a template, so omit it from the ETag.
fresh_when @post, template: false