How to tune your cache settings

Boost your application's efficiency with strategic cache handling with custom cache TTL values, object segmentation methods, and large file optimization.

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Leverage the capabilities of Cache to configure your application’s cache policies, including expiration values at the edge or browser level, large file optimization to break large files into smaller chunks, and cache key segmentation based on HTTP methods, query strings, cookies, or device groups.

When you first create an application, a cache setting variable will be created and activated by default. This guide will show you how to create and activate a brand new cache setting instance.

  1. Access Azion Console > Applications.
  2. Click the application you want to configure.
  3. Activate the Application Accelerator module to unlock advanced cache key configurations.
  4. Click the Save button.
  5. Navigate to the Cache Settings tab.
  6. Click the + Cache Setting button.
  7. Give your cache setting a name.

Cache Expiration Policies

You can customize the cache Time To Live (TTL) in browsers and at the edge. This data is sent in requests and responses through the Cache-Control and Expires HTTP headers.

The TTL determined by the max-age directive in Cache-Control. If Cache-Control isn’t present in the request or response, the timestamp sent in the Expires header determines the cache TTL.

  1. In Browser Cache, select Override cache settings to determine a custom TTL value.
  2. Add the TTL in seconds in the Max Age (seconds) field. For example: 432000 = 5 days.

In Cache, you can determine whether the edge should abide by the values sent in the Cache-Control and Expires headers.

You can choose to keep Honor cache policies selected to respect the TTL values sent in the headers by the origin or the application itself.

If your application isn’t sending Cache-Control and Expires headers or the values aren’t set correctly, you can determine a default maximum TTL for the cache to be maintained at the edge in the Max Age (seconds) field. If your application is sending these values, to override them:

  1. In Cache, select Override cache settings to determine a custom TTL value.
  2. Add the TTL in seconds in the Max Age (seconds) field. For example: 864000 = 10 days.

The maximum and default TTL values for the edge should be between 60 and 31536000 seconds (1 year). If you have the Application Accelerator module activated, you can set this value to a minimum of 0. Additionally, if you have the Cache module activated and wish to maintain cache in the cache layer, you must set TTL to at least 3 seconds.

A TTL zero isn’t the same as a cache bypass. For more details, read about the difference between these settings on the Bypass Cache behavior documentation.

Stale cache

Azion provides the capability to serve stale content from the cache when the origin server is down or while the cache is being renewed. The Stale cache feature is enabled by default, allowing your application to continue serving the most recent cached content during these events.

Large file optimization

Instead of downloading a large content file and risking timeouts or connection terminations, files can be fragmented into smaller pieces and cached on-demand.

  1. In Large file optimization, enable the switch to activate.
  2. The Cache layer is already selected by default. If you have the Cache module activated, you can also enable this feature for the cache layer.

The default fragment size is of 1024 kB.

Application Accelerator

This section lets you customize how cache varies based on HTTP methods, query string fields, cookies and device groups through cache keys. You can choose to segment cache keys using these attributes to control how objects are stored and served from the cache.

To determine content variation in cache:

  1. In Cache vary by Method, activate the Enable caching for POST switch to cache POST requests and the Enable caching for OPTIONS switch to cache OPTIONS requests.

  2. In Cache vary by Query String, select Content varies by some query string fields (Allowlist).

  3. In Query string fields, add the value city.

  • This field is case‑sensitive and treats uppercase and lowercase letters differently when storing objects in the cache.

When a request is made to an application URL xxxxxxxxxx.map.azionedge.net/page?city=12345, the cache key for this URL will be different from cache keys made to xxxxxxxxxx.map.azionedge.net/page and any other queries appended to the URL.

Use the Content varies by query string, except for some fields (Blocklist) option to do the reverse: keep all requests with query strings as different cache keys; the ones specified in Query string fields will be grouped into a single cache key.

To disregard the order of the data sent in the query string and keep objects with the same query string values as a single cache key:

  1. Enable the Query String sort switch.

  2. In Cache vary by Cookies, select Content varies by some cookies (Allowlist).

  3. In Cookie names, add the value cookie_name.

  • This field is case‑sensitive and treats uppercase and lowercase letters differently when storing objects in the cache.

When a request is made to an application and the response from the origin sends a Set‑Cookie header, the objects in the Cookie request header that contain the name cookie_name, regardless of value, will be considered as a different object in cache from other requests.

Use the Content varies by cookies, with the exception of a few (Blacklist) option to do the reverse: keep all requests with cookies as different cache keys; the ones specified in the Cookie names will be grouped into a single cache key.

  1. In Cache vary by Devices, select Content varies by some device groups (Allowlist).
  2. Click the + Add Device Group button to add a device group and select it from the list.
  3. Repeat the previous step for every device group you wish to specify a different cache key.

Once you’ve finished configuring your cache setting:

  1. Click the Save button.

Activating your cache setting

The cache settings page now lists the newly created instance. However, this new cache setting isn’t active in your application. You need to define what will trigger the implementation of the cache policies in your application. For this, you can use your application’s Rules Engine.

The instructions below will help you create a rule in which any request from your users to xxxxxxxxxx.map.azionedge.net/cache will apply the cache setting you created.

  1. Navigate to the Rules Engine tab.
  2. Click the + Rule button.
  3. Give a name for your rule.
  4. Select Request Phase.
  5. Under the Criteria section, select the variable ${uri}.

The ${uri} variable may already be selected by default if you didn’t activate the Application Accelerator module.

  1. As a comparison operator, select is equal.
  2. As an argument, add /cache.
  3. In the Behaviors section, select Set Cache Policy from the behavior list.
  4. Select the new cache setting you created.
  5. Click the Save button.
  6. Wait a few minutes for the changes to propagate.

To verify how your content is being cached, you can verify application cache indicators using Modheader for Google Chrome.