Setting up custom cache tags to reduce Varnish misses on views page

To prevent a view page from being invalidated by all node changes, it may be desired to set up custom cache tags. 

If a site has hundreds of views and nodes of content, invalidating the caches of these views can add performance issues because every node change invalidates every view. As a result, the view page will get more Varnish cache misses than hits.

To improve the Varnish cache hit-rate on views pages, use the Views Custom Cache Tag module:

Drupal 8 automatically adds cache tags to every view so that their content can be invalidated when any of the content changes... However, Drupal 8 only has a single list cache tag for every entity type. Every view that lists nodes is tagged with node_list and will be invalidated when a node is added, changed or deleted.

This module replaces the hardcoded cache tag with a form that allows developers to set different cache tags based on configuration of the view.

To use this module and set up custom cache tags:

• Edit the View.
• Go to Advanced and click on "Caching: Tag based".
• Select "Custom tag based".
• Insert a custom cache tag, e.g. node:type:page.
• Save the view.

Next, use hook_node_presave() in a helper module or custom module:

// For hook_ENTITY_TYPE_presave.
use Drupal\Core\Cache\Cache;
use Drupal\Core\Entity\EntityInterface;

/**
* Implements hook_ENTITY_TYPE_presave().
*
* Invalid cache tags for node lists.
*/

function kb_invalidate_custom_cache_tags_node_presave(EntityInterface $entity) {
$cache_tag = 'node:type:' . $entity->getType(); Cache::invalidateTags([$cache_tag]); }

This hook will be fired each time a node is created or updated to invalidate the cache of only the specified node types.