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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:
State | Description |
---|---|
Miss | The request could be satisfied in cache, but an entry for the resource was not found in cache, and the request was proxied upstream. |
Hit | The request was satisfied and served from the cache. |
Refresh | The resource was found in cache, but could not satisfy the request, due to Cache-Control behaviors or reaching its hard-coded cache_ttl threshold. |
Bypass | The request could not be satisfied from cache based on plugin configuration. |
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