# SSR Cache

Vue Storefront generates the server-side rendered pages and from version to improve SEO results. In the latest version of Vue Storefront, we added the output cache option (disabled by default) to improve performance - for both Vue Storefront and Vue Storefront API.

Caution !

Vue Storefront API uses exactly the same output cache mechanisms like Vue Storefront with the same configuration and CLI interface.

The output cache is set by the following config/local.json variables:

    "server": {
      "host": "localhost",
      "port": 3000,
      "protocol": "http",
      "api": "api",
      "useOutputCacheTagging": true,
      "useOutputCache": true,
      "outputCacheDefaultTtl": 86400,
      "invalidateCacheKey": "aeSu7aip",
      "invalidateCacheForwarding": false,
      "invalidateCacheForwardUrl": "http://localhost:8080/invalidate?key=aeSu7aip&tag=",      
    },
    "redis": {
      "host": "localhost",
      "port": 6379,
      "db": 0
    },

# Dynamic tags

The dynamic tags config option: useOutputCacheTagging - if set to true, Vue Storefront is generating the special HTTP Header X-VS-Cache-Tags

res.setHeader('X-VS-Cache-Tags', cacheTags);

Cache tags are assigned regarding the products and categories that are used on the specific page. A typical X-VS-Cache-Tags tag looks like this:

X-VS-Cache-Tags: P1852 P198 C20

The tags can be used to invalidate the Varnish cache, if you're using it. Read more on that.

# Redis

If both useOutputCache and useOutputCacheTagging options are set to true, Vue Storefront is using output cache stored in Redis (configured in the redis section of the config file). Cache is tagged with dynamic tags and can be invalidated using a special webhook:

An example call to clear all pages containing specific product and category:

curl http://localhost:3000/invalidate?tag=P1852,C20

An example call to clear all product, category, and homepages:

curl http://localhost:3000/invalidate?tag=product,category,home

Caution !

We strongly recommend you DO NOT USE output cache in development mode. By using it, you won't be able to refresh the UI changes after modifying the Vue components, etc.

# CLI cache clear

You can manually clear the Redis cache for specific tags by running the following command:

yarn cache clear
yarn cache clear -- --tag=product,category
yarn cache clear -- --tag=P198
yarn cache clear -- --tag=*

Note: The commands presented above works exactly the same way in the vue-storefront-api.

Available tag keys are set in the config.server.availableCacheTags (by default: "product", "category", "home", "checkout", "page-not-found", "compare", "my-account", "P", "C")

Dynamic cache invalidation: Recent version of mage2vuestorefront supports output cache invalidation. Output cache is tagged with the product and categories ID (products and categories used on a specific page). Mage2vuestorefront can invalidate the cache of a product and category pages if you set the following ENV variables:

export VS_INVALIDATE_CACHE_URL=http://localhost:3000/invalidate?key=SECRETKEY&tag=
export VS_INVALIDATE_CACHE=1

Caution !

All the official Vue Storefront data indexers including magento1-vsbridge-indexer, magento2-vsbridge-indexer and mage2vuestorefront support the cache invalidation. If the cache is enabled in both API and Vue Storefront frontend app, please make sure you are properly using the config.server.invalidateCacheForwardUrl config variable as the indexers can send the cache invalidate request only to one URL (frontend or backend) and it should be forwarded. Please check the default forwarding URLs in the default.json and adjust the key parameter to the value of server.invalidateCacheKey.

For magento1-vsbridge-indexer and magento2-vsbridge-indexer please do use the proper settings in the Magento admin panel.

Security note

Please note that key=SECRETKEY should be equal to vue-storefront/config/local.json value of server.invalidateCacheKey

# Adding new types / cache tags

If you're adding a new type of page (core/pages) and config.server.useOutputCache=true, you should also extend the config.server.availableCacheTags of new general purpose tag that will be connected with the URLs connected with this new page.

After doing so, please add the asyncData method to your page code assigning the right tag (please take a look at core/pages/Home.js for instance):

  asyncData ({ store, route, context }) { // this is for SSR purposes to prefetch data
    return new Promise((resolve, reject) => {
      if (context) context.output.cacheTags.add(`home`)
      Logger.log('Entering asyncData for Home root ' + new Date())()
      EventBus.$emitFilter('home-after-load', { store: store, route: route }).then((results) => {
        return resolve()
      }).catch((err) => {
        Logger.error(err)()
        reject(err)
      })
    })
  },

This line:

if (context) context.output.cacheTags.add(`home`);

is in charge of assigning the specific tag with current HTTP request output.

# Caching strategies on production

When it comes to caching on production, we made a set of caches at each layer of Vue Storefront infrastructure. There is a section about Production setup in our guide. Additionally read this article for more details.