Edge Security Acceleration:Create custom cache keys

What is cache key

A cache key is the unique ID of a file that is cached on a point of presence (POP). Each file that is cached on POPs has a cache key. By default, the cache key of a file is the URL in the request that is sent to retrieve the file. The URL contains parameters.

How custom cache key works

Custom cache keys do not alter origin URLs, but only modify the cache identifiers in requests. Requests that are redirected to origin servers and that are sent by clients are intended for the same content.

Scenarios

Scenario 1: Identical cache keys

The URLs in requests may contain complex parameters. Therefore, even if the requests are sent to retrieve the same content, due to the variation of URL parameters, POPs consider that the requests are sent to retrieve different resources and then cache resources for all requests. As a result, a large number of requests are routed to the origin server.

You can use the custom cache key feature to ignore query strings and set a cache key for a type of requests to reduce the number of origin requests.

Scenario 2: Different cache keys

The requests contain the same URL. In this case, DCDN considers that the requests are sent to retrieve the same resource. However, in fact, the client OSs are specified in the client field of the HTTP header in the requests. The requests may be sent to retrieve different files.

You can create two cache keys, include the values of the client field in the cache keys, and then use the cache keys to distinguish the requests.

Set custom cache keys

1. In the ESA console, choose Websites and click the website name you want to manage.

2. In the left-side navigation pane, choose Rules > Cache Rules.

3. Click Create Rule, and fill in the Rule Name.

4. In the If Requests Match... area, specify the conditions for matching incoming requests. For more information about how to configure a rule, see Rules.

5. In the Bypass Cache section, specify whether to bypass cache. For more information, see Bypass cache.

6. In the Custom Cache Keys section, click Configure and configure the following parameters.

   

   Parameter	Description
   Sort Query Strings	Specify whether to sort query strings. For more information, see Sort query strings.
   Query String	Specify whether to remove the question mark (?) and query string that follows the question mark (?) from the request URL. For more information, see Query string.
   HTTP Request Header	Include Header Names and Their Values: adds specific HTTP request headers and their values to the cache key. Check Presence of: checks whether the specific HTTP request headers exist and adds the HTTP headers to the cache key if the HTTP request headers exist.
   Cookie	Include Cookie Names and Their Values: adds specific cookie names and their values to the cache key. Check Presence of: checks whether the specific cookies exist and adds the cookies to the cache key if the cookies exist.
   User	Device Type: identifies the client type based on the User-Agent header and generates a cache key based on the client type. Country/Region: identifies the country or region where the client resides based on the client IP address and generates a cache key based on the country or region. Language: identifies the client language based on the Accept-Language header in the request and generates a cache key based on the language.

7. Click OK.

Configuration example