# Application Accelerator settings [Application Accelerator](/en/documentation/platform/applications/#application-accelerator) is a module of [Applications](/en/documentation/platform/applications/), turned on for one application at a time. The module unlocks the cache fields that vary the cache key, the caching of `POST` and `OPTIONS` responses, and seven [Rules Engine](/en/documentation/platform/applications/rules-engine/) behaviors. This page carries the name, the type, and the default of each field, and the interface that sets it. --- ## Module activation The module is off by default, and every interface below sets the same toggle. The toggle belongs to the application, not to a cache setting, so one application can carry it while another does not. | Interface | Where you set it | Field or flag | | -------------------------------------------------------------------- | ---------------------------------------------------------------------- | ----------------------------------------- | | Azion Console | The **Modules** section of the **Main Settings** tab of an application | The **Application Accelerator** switch | | Azion API v4 | `PATCH /workspace/applications/{id}` | `modules.application_accelerator.enabled` | | [Azion CLI](/en/documentation/devtools/cli/) | `azion update application` | `--application-accelerator` | | [`azion.config.js`](/en/documentation/devtools/cli/azion-config-js/) | The `AzionApplication` object | `applicationAcceleratorEnabled` | | [Azion Lib](/en/documentation/devtools/azion-lib/application/) | The data passed to an application create or update | `application_acceleration` | `modules.application_accelerator.enabled` is a boolean and defaults to `false`. `applicationAcceleratorEnabled` and `application_acceleration` are booleans, and the Azion CLI flag takes a string. The [Azion Terraform provider](/en/documentation/devtools/terraform/) manages the application resource that carries the module. Turning on a module can generate usage-related costs. For more information, refer to [Pricing](/en/documentation/fundamentals/pricing/#application-accelerator). --- ## Cache variation Application Accelerator adds the `modules.application_accelerator` object to a cache setting, and the fields in it configure **Advanced Cache Key**. They decide which parts of a request, beyond the URL, produce a separate cached object. In Azion Console, the same fields sit in the **Application Accelerator** section of a cache setting. A variation appends the `@@` separator to the cache key. For the format of a cache key, refer to [Cache key format](/en/documentation/platform/applications/cache/cache-keys/#key-format). | Field | Type | Default | Console control | What it sets | | ---------------------------------------- | -------------------------------------------------- | -------- | ----------------------------------------------------- | ------------------------------------------------------------------- | | `cache_vary_by_method` | array of enum, at most 2 values: `options`, `post` | `[]` | **Cache vary by Method**, one checkbox per method | The request methods whose responses are cached. | | `cache_vary_by_querystring.behavior` | enum: `ignore`, `all`, `allowlist`, `denylist` | `ignore` | **Cache vary by Query String** > **Behavior** | The mode that decides how the query string varies the key. | | `cache_vary_by_querystring.fields` | array of string | `[]` | The field list under **Cache vary by Query String** | The query string arguments the mode applies to. | | `cache_vary_by_querystring.sort_enabled` | boolean | `false` | **Cache vary by Query String** > **Sort** | Whether the variations group under one key, ordered alphabetically. | | `cache_vary_by_cookies.behavior` | enum: `ignore`, `all`, `allowlist`, `denylist` | `ignore` | **Cache vary by Cookies** > **Behavior** | The mode that decides how cookies vary the key. | | `cache_vary_by_cookies.cookie_names` | array of string | `[]` | The cookie list under **Cache vary by Cookies** | The cookies the mode applies to. | | `cache_vary_by_devices.behavior` | enum: `ignore`, `allowlist` | `ignore` | **Cache vary by Devices** > **Behavior** | The mode that decides how device groups vary the key. | | `cache_vary_by_devices.device_group` | array of integer | `[]` | The device group list under **Cache vary by Devices** | The device groups the mode applies to. | Each **Behavior** dropdown renders the values of its enum title-cased: *Allowlist*, *Denylist*, *Ignore*, and *All*. One field on the same cache setting sits outside that object and is still gated by the module: | Field | Type | Default | Console control | What it sets | | ----------------------- | ---------------------------------- | ------- | ----------------------- | -------------------------------------------------------------------------- | | `modules.cache.max_age` | integer, `0` to `31536000` seconds | `60` | **Cache** > **Max Age** | How long the cache holds the object. A value below 60 requires the module. | For the ceilings that bound a cache setting, refer to [Limits](/en/documentation/platform/applications/limits/#application-accelerator). --- ## Cache setting flags in Azion CLI `azion create cache-setting` writes the same fields from the command line. Each flag below sets one field of the cache setting. | Flag | Field it sets | Default | | ------------------------------ | ------------------------------------ | -------- | | `--cache-by-query-string` | `cache_vary_by_querystring.behavior` | `ignore` | | `--query-string-fields` | `cache_vary_by_querystring.fields` | None | | `--cache-by-cookies` | `cache_vary_by_cookies.behavior` | `ignore` | | `--cookie-names` | `cache_vary_by_cookies.cookie_names` | None | | `--enable-caching-for-post` | `post` in `cache_vary_by_method` | None | | `--enable-caching-for-options` | `options` in `cache_vary_by_method` | `false` | Azion CLI does not set device-group variation, and it does not set the maximum age of the cache: `--browser-cache-max-age` sets the browser value alone. --- ## HTTP methods An application natively accepts `GET` and `HEAD`. Application Accelerator adds five more methods, and the responses of two of them can be cached through `cache_vary_by_method`. | Method added by the module | Response can be cached | | -------------------------- | -------------------------------------------------- | | `OPTIONS` | Yes, when `cache_vary_by_method` carries `options` | | `POST` | Yes, when `cache_vary_by_method` carries `post` | | `PUT` | No | | `PATCH` | No | | `DELETE` | No | A cached `POST` or `OPTIONS` object gets its own cache key. For the shape of that key, refer to [Cached HTTP methods](/en/documentation/platform/applications/cache/cache-keys/#variations). --- ## Rules Engine behaviors Seven Rules Engine behaviors require Application Accelerator on the application that runs the rule. The table indexes them; [Rules Engine](/en/documentation/platform/applications/rules-engine/#behaviors) owns the arguments and the syntax of each one. | Behavior | Phases | What it does | | -------------------------------------------------------------------------------------------------- | ----------------- | ------------------------------------------------------------------------------------------------------------------ | | [Add Cookie](/en/documentation/platform/applications/rules-engine/#add-cookie) | Request, Response | Adds a cookie to the `Set-Cookie` header. | | [Bypass Cache](/en/documentation/platform/applications/rules-engine/#bypass-cache) | Request | Stops Azion from caching the origin response, and leaves the browser cache untouched. | | [Capture Match Groups](/en/documentation/platform/applications/rules-engine/#capture-match-groups) | Request, Response | Stores the result of a regular expression capture over a request field in a temporary variable. | | [Filter Cookie](/en/documentation/platform/applications/rules-engine/#filter-request-cookie) | Request, Response | Removes a cookie from the request header sent to the origin, or from the response header sent to the user. | | [Forward Cookies](/en/documentation/platform/applications/rules-engine/#forward-cookies) | Request | Forwards the `Set-Cookie` header of the origin to users, including on a cache hit. | | [Rewrite Request](/en/documentation/platform/applications/rules-engine/#rewrite-request) | Request | Modifies the resource path requested from the origin. | | [Run Function](/en/documentation/platform/applications/rules-engine/#run-function) | Request, Response | Runs a function instantiated on the application. Also requires [Functions](/en/documentation/platform/functions/). | Rule criteria can read `${device_group}`, which requires the module as well. For the variable, refer to [Variables](/en/documentation/platform/applications/rules-engine/#variables), and for the groups it matches, refer to [Device Groups](/en/documentation/platform/applications/device-groups/). [Set Cache Policy](/en/documentation/platform/applications/rules-engine/#set-cache-policy) does not require the module. It assigns a cache policy created in [Cache Settings](/en/documentation/platform/applications/cache/cache-settings/), and it is how a cache setting reaches a request. --- ## Related resources - [Cache variation](/en/documentation/platform/applications/application-accelerator/cache-variation.md): How each of these fields changes the cache key, and what a variation costs. - [Quickstart](/en/documentation/platform/applications/application-accelerator/quickstart.md): Turn the module on and create a cache setting that varies the cache key. - [Limits](/en/documentation/platform/applications/limits.md#application-accelerator): The ceilings that bound the values in these tables. - [Real-Time Purge](/en/documentation/platform/applications/cache/real-time-purge.md): How to purge an object that varies by cookie, query string, or device group.