Bubbleable metadata

The parent page explains cacheability in general. This looks in detail at how render arrays bubble cacheability.

Concepts

• Cacheability metadata: contexts, tags, max-age. TO BE EXPANDED
• Bubbleable metadata: cacheability metadata + #attached + #post_render_cache callbacks. TO BE EXPANDED
• Default render cache contexts: every render array that uses #theme uses templates of the negotiated theme, and almost every render array contains translated strings (i.e. text wrapped in a t() call). That's why Drupal adds the corresponding cache contexts ('theme' and 'languages:' . LanguageInterface::TYPE_INTERFACE, respectively) by default. The default cache contexts are specified in the %renderer.config% container parameter's required_cache_contexts key.
  (Note: for very advanced use cases, sites can choose to override those default required cache contexts.)

TO BE EXPANDED