caching.md

Caching

AppSync supports server-side data caching. You can find the caching configuration under the appSync.caching attribute.

Quick start

appSync:
  name: my-api
  caching:
    behavior: 'PER_RESOLVER_CACHING'
    type: 'SMALL'
    ttl: 3600
    atRestEncryption: false
    transitEncryption: false

Configuration

• behavior: FULL_REQUEST_CACHING or PER_RESOLVER_CACHING
• type: The type of the Redis instance. SMALL, MEDIUM, LARGE, XLARGE, LARGE_2X, LARGE_4X, LARGE_8X, LARGE_12X. Defaults to SMALL
• ttl: The default TTL of the cache in seconds. Defaults to 3600. Maximum is 3600
• enabled: Boolean. Whether caching is enabled. Defaults to true when the caching definition is present.
• atRestEncryption: Boolean. Whether to encrypt the data at rest. Defaults to false
• transitEncryption: Boolean. Whether to encrypt the data in transit. Defaults to false

Per resolver caching

See Resolver caching

Evicting items from the cache

To evict a single entry from the cache (rather than flushing everything), use AppSync's evictFromApiCache extension from within a resolver. This is a runtime feature of AppSync, so there is nothing special to configure in this plugin: just call it from the mapping template or JavaScript code of the resolver, and it is passed through to AppSync as-is.

A few things to keep in mind (see the AppSync docs for the details):

• It only works in mutation resolvers, not queries.
• The target entry is identified by the type name, field name, and a map of caching keys. The keys must match — in the same order — the keys of the cached resolver you want to evict.

For example, given a cached query resolver:

appSync:
  resolvers:
    Query.getNote:
      dataSource: notes
      caching:
        ttl: 60
        keys:
          - '$context.arguments.id'

You can evict its cached entry from a mutation resolver. With a VTL response template:

#set($keys = {})
$util.qr($keys.put("context.arguments.id", $ctx.args.id))
$extensions.evictFromApiCache("Query", "getNote", $keys)
$util.toJson($ctx.result)

Or with a JavaScript resolver:

import { extensions } from '@aws-appsync/utils';

export function response(ctx) {
  extensions.evictFromApiCache('Query', 'getNote', {
    'context.arguments.id': ctx.args.id,
  });
  return ctx.result;
}

Flushing the cache

You can use the flush-cache command to easily flush the cache.