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Proxy Caching

One of the ways Kong delivers performance is through caching. The Proxy Cache plugin accelerates performance by caching responses based on configurable response codes, content types, and request methods. When caching is enabled, upstream services are not impacted by repetitive requests, because Kong Gateway responds on their behalf with cached results. Caching can be enabled on specific routes for all requests globally.

Create a proxy-cache KongClusterPlugin

In the previous section you created a KongPlugin that was applied to a specific service or route. You can also use a KongClusterPlugin which is a global plugin that applies to all services.

This configuration caches all HTTP 200 responses to GET and HEAD requests for 300 seconds:

echo '
apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: proxy-cache-all-endpoints
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: "true"
plugin: proxy-cache
config:
  response_code:
  - 200
  request_method:
  - GET
  - HEAD
  content_type:
  - text/plain; charset=utf-8
  cache_ttl: 300
  strategy: memory
' | kubectl apply -f -

Test the proxy-cache plugin

To test the proxy-cache plugin, send another six requests to $PROXY_IP/echo:

for i in `seq 6`; do curl -sv $PROXY_IP/echo 2>&1 | grep -E "(Status|< HTTP)"; done

The first request results in X-Cache-Status: Miss. This means that the request is sent to the upstream service. The next four responses return X-Cache-Status: Hit which indicates that the request was served from a cache.

The X-Cache-Status header can return the following cache results:

The final thing to note is that when a HTTP 429 request is returned by the rate-limit plugin, you do not see a X-Cache-Status header. This is because rate-limiting executes before proxy-cache. For more information, see plugin priority.

< HTTP/1.1 200 OK
< X-Cache-Status: Miss
< HTTP/1.1 200 OK
< X-Cache-Status: Hit
< HTTP/1.1 200 OK
< X-Cache-Status: Hit
< HTTP/1.1 200 OK
< X-Cache-Status: Hit
< HTTP/1.1 200 OK
< X-Cache-Status: Hit
< HTTP/1.1 429 Too Many Requests