--- name: azion-configure-advanced-cache-key-for-an-application description: >- Vary a cached object by a query string argument or by a cookie, then apply the cache setting to an application with a Rules Engine rule. --- # Configure Advanced Cache Key for an application [Application Accelerator](/en/documentation/platform/applications/#application-accelerator) unlocks [Advanced Cache Key](/en/documentation/platform/applications/cache/cache-settings/#application-accelerator), which varies a cached object by query string argument or by cookie. You configure it in a cache setting from Azion Console, then apply that cache setting with [Rules Engine](/en/documentation/platform/applications/rules-engine/). For content that does not vary between requests, refer to [Configure cache policies](/en/documentation/guides/application-performance/cache-and-purge/cache-settings/). For what a variation changes in the cache key, refer to [Cache variation](/en/documentation/platform/applications/application-accelerator/cache-variation/). --- ## Prerequisites - An application. To create one, refer to [Applications quickstart](/en/documentation/platform/applications/quickstart/). - Access to Azion Console. Refer to [Access Azion Console](/en/documentation/guides/platform/account-and-billing/how-to-access-azion-console/). - Application Accelerator can generate usage-related costs. For the rates, refer to [Pricing](/en/documentation/fundamentals/pricing/#application-accelerator). --- ## Turn on Application Accelerator The module is off by default, and a cache setting varies the cached object only while the module is on. To turn it on: 1. **Open the application** Access [Azion Console](https://console.azion.com/) > **Applications** > **your application**. 2. **Turn on the module** On the **Main Settings** tab, in the **Modules** section, turn on **Application Accelerator**. 3. **Select Save** The application runs with Application Accelerator, and its cache settings can vary the cached object by query string or cookie. --- ## Vary the cache by a query string argument An application serves the URL `domain.com/page?city=city_name`. The `/page` URI calls an API that lists content for the city in the `city` argument. The API refreshes that content every five minutes. To store one object per city, and to expire it at the same interval: 1. **Open the Cache Settings tab** Access [Azion Console](https://console.azion.com/) > **Applications** > **your application**, then go to the **Cache Settings** tab. 2. **Select + Cache** 3. **Name the cache setting** In **Name**, enter a name that identifies the setting. For example: `city-listing`. 4. **Set the browser cache** Under **Browser Cache**, select *Override cache settings* and set the maximum age to `300`. 5. **Set Max Age** Under **Cache**, select *Override cache behavior* and set **Max Age** to `300`. 6. **Allowlist the argument** Under **Application Accelerator**, open **Cache vary by Query String** and set **Behavior** to *Allowlist*. 7. **Enter the argument** Add `city` to the list of query string arguments. 8. **Select Save** The cache setting appears in the **Cache Settings** tab, and it varies the cached object by the `city` argument. > **Note** > > Cache keys are case sensitive. Azion stores `?city=Lisbon` and `?city=lisbon` as two objects. A cache setting takes effect only when a rule applies it. To apply this one to the `/page` URI: 1. **Go to the Rules Engine tab** 2. **Select + Rule** 3. **Name the rule** Enter a name for the rule. For example: `city-listing rule`. 4. **Select Request Phase** 5. **Select the variable in the Criteria section** In the **Criteria** section, select the `${uri}` variable. 6. **Select starts with as the comparison operator** 7. **Enter the argument** Enter `/page` as the argument. 8. **In the Behaviors section, select Set Cache Policy** 9. **Select the cache setting you created** 10. **Select Save** Requests whose URI starts with `/page` carry the cache setting. The browser and Azion hold each city object for 300 seconds. A new rule takes a few minutes to propagate. --- ## Vary the cache by a cookie An application authenticates users with a cookie, and the `/profile` page it serves after a login must differ per session. The cookie `session_cookie` carries the value that identifies the session. To store one object per session: 1. **Open the Cache Settings tab** Access [Azion Console](https://console.azion.com/) > **Applications** > **your application**, then go to the **Cache Settings** tab. 2. **Select + Cache** 3. **Name the cache setting** In **Name**, enter a name that identifies the setting. For example: `profile-by-session`. 4. **Set the cache behavior** In the **Browser Cache** and **Cache** sections, set the behavior and the age the profile page needs. 5. **Allowlist the cookie** Under **Application Accelerator**, open **Cache vary by Cookies** and set **Behavior** to *Allowlist*. 6. **Enter the cookie name** Add `session_cookie` to the list of cookie names. 7. **Select Save** The cache setting appears in the **Cache Settings** tab, and it varies the cached object by the value of `session_cookie`. Cookie names are case sensitive, like every value that composes a cache key. To apply this cache setting to the `/profile` URI: 1. **Go to the Rules Engine tab** 2. **Select + Rule** 3. **Name the rule** Enter a name for the rule. For example: `profile rule`. 4. **Select Request Phase** 5. **Select the variable in the Criteria section** In the **Criteria** section, select the `${uri}` variable. 6. **Select starts with as the comparison operator** 7. **Enter the argument** Enter `/profile` as the argument. 8. **In the Behaviors section, select Set Cache Policy** 9. **Select the cache setting you created** 10. **Select Save** Requests whose URI starts with `/profile` carry the cache setting. Each session receives the object cached for its own `session_cookie` value. A new rule takes a few minutes to propagate. --- ## Next steps - [Cache variation](/en/documentation/platform/applications/application-accelerator/cache-variation.md): What a variation changes in the cache key, and what it costs you in stored objects. - [Application Accelerator settings](/en/documentation/platform/applications/application-accelerator/settings.md): Every field the module adds to a cache setting, with its values and defaults. - [Real-Time Purge](/en/documentation/platform/applications/cache/real-time-purge.md): Expire an object that varies, which a URL purge does not always reach. - [Verify cache indicators with ModHeader](/en/documentation/guides/application-performance/cache-and-purge/check-page-cache-time.md): Read the cache headers a request returns and confirm the variation you configured. - [Optimize images for websites and mobile apps](/en/documentation/use-cases/improve-performance-and-reliability/optimize-images-for-websites-and-mobile-apps.md): A cache setting that varies by the ims argument, so each image size is cached once.