# Environment variables for custom test environments
<a name="custom-test-environment-variables"></a>

 Device Farm dynamically configures several environment variables for use as part of your custom test environment run. 

**Topics**
+ [Custom environment variables](#custom-test-environment-variables-custom)
+ [Common environment variables](#custom-test-environment-variables-common)
+ [Environment variables for Appium tests](#custom-test-environment-variables-appium)
+ [Environment variables for XCUITest tests](#custom-test-environment-variables-xcuitest)

## Custom environment variables
<a name="custom-test-environment-variables-custom"></a>

 Device Farm supports the configuration of key-value pairs that are applied as environment variables on the test host. These may be configured on a Device Farm project or during run creation; any variables configured on a run will supersede any that may be configured on its parent project. The following restrictions apply: 
+ Custom environment variables are not supported on legacy iOS test hosts. For more information, see [Legacy iOS test host](custom-test-environments-hosts-ios.md#legacy-ios-host).
+ Variable names beginning with `$DEVICEFARM_` are reserved for internal service use.
+ Custom environment variables may not be used to configure test host compute selection in your test spec.

## Common environment variables
<a name="custom-test-environment-variables-common"></a>

 This section describes environment variables common to all tests in Device Farm. 

** `$DEVICEFARM_DEVICE_NAME` **  
 The device on which your tests run. It represents the unique device identifier (UDID) of the device. 

** `$DEVICEFARM_DEVICE_UDID` **  
 The device's unique identifier. 

** `$DEVICEFARM_DEVICE_PLATFORM_NAME` **  
 The device's platform name. It is either `Android` or `iOS`. 

** `$DEVICEFARM_DEVICE_OS_VERSION` **  
 The device's OS version. 

** `$DEVICEFARM_APP_PATH` **  
 *(mobile app tests)*   
 The path to the mobile app on the host machine where the tests are being executed. This variable is not available during web tests. 

** `$DEVICEFARM_LOG_DIR` **  
 The path to the default directory where customer logs, artifacts, and other wanted files will be stored for later retrieval. Using an [example test spec](custom-test-environment-test-spec.md#custom-test-environment-test-spec-example), files in this directory are archived in a ZIP file and made available as an artifact after your test run. 

** `$DEVICEFARM_SCREENSHOT_PATH` **  
 The path to the screenshots, if any, captured during the test run. 

** `$DEVICEFARM_PROJECT_ARN` **  
 The ARN of the job's parent project. 

** `$DEVICEFARM_RUN_ARN` **  
 The ARN of the job's parent run. 

** `$DEVICEFARM_DEVICE_ARN` **  
 The ARN of the device under test. 

** `$DEVICEFARM_TOTAL_JOBS` **  
 The total number of jobs associated with its parent Device Farm run. 

** `$DEVICEFARM_JOB_NUMBER` **  
 This job's number within `$DEVICEFARM_TOTAL_JOBS`. For example, a run may contain 5 jobs, and each will have a unique `$DEVICEFARM_JOB_NUMBER` ranging from 0 to 4. 

** `$AWS_REGION` **  
 The AWS region. The service will set this to match the region in which the device under test is located. It can be overridden by a custom environment variable if needed. 

** `$ANDROID_HOME` **  
 *(Android only)*   
 The path to the Android SDK installation directory. 

## Environment variables for Appium tests
<a name="custom-test-environment-variables-appium"></a>

 This section describes environment variables used by any Appium test in a custom test environment in Device Farm. 

** `$DEVICEFARM_CHROMEDRIVER_EXECUTABLE_DIR` **  
 *(Android only)*   
 The location of a directory which contains the necessary ChromeDriver executables for use in Appium web and hybrid tests. 

** `$DEVICEFARM_APPIUM_WDA_DERIVED_DATA_PATH_V<N>` **  
 *(iOS only)*   
 The derived data path of a version of WebDriverAgent built to run on Device Farm. The numbering on the variable will correspond to the major version of the WebDriverAgent. As an example, `DEVICEFARM_APPIUM_WDA_DERIVED_DATA_PATH_V9` will point to the a WebDriverAgent version of 9.x. For more information, see [Selecting a WebDriverAgent version for iOS tests](test-types-appium.md#test-types-appium-select-wda).  
 The `$DEVICEFARM_APPIUM_WDA_DERIVED_DATA_PATH_V<N>` environment variables are only present on non-legacy iOS hosts. For more information, see [Legacy iOS test host](custom-test-environments-hosts-ios.md#legacy-ios-host). 

** `$DEVICEFARM_WDA_DERIVED_DATA_PATH_V9` **  
 *(iOS only, deprecated)*   
 The derived data path of a version of WebDriverAgent built to run on Device Farm. Refer to `$DEVICEFARM_APPIUM_WDA_DERIVED_DATA_PATH_V<N>` for the replacement naming scheme.

## Environment variables for XCUITest tests
<a name="custom-test-environment-variables-xcuitest"></a>

 This section describes environment variables used by the XCUITest test in a custom test environment in Device Farm. 

** `$DEVICEFARM_XCUITESTRUN_FILE` **  
 The path to the Device Farm `.xctestun` file. It is generated from your app and test packages. 

** `$DEVICEFARM_DERIVED_DATA_PATH` **  
Expected path of Device Farm xcodebuild output.

** `$DEVICEFARM_XCTEST_BUILD_DIRECTORY` **  
The path to the unzipped contents of the test package file.