Set Environment Variables
Configure your environment variables to allow App Percy builds to run seamlessly.
App Percy is designed to integrate with your tests locally and with your CI environment. To establish this integration, set the PERCY_TOKEN environment variable by following these steps:
IMPORTANT
- Keep your Percy token secret. Anyone with access to your token can consume your account quota.
- The “write-only” token can only be used to make changes, not to view your data.
Get PERCY_TOKEN
A Percy token is generated when you create an App Percy project. The token is a write-only API key that is unique for each project. You can find this on the Project Settings page.
You can set a project-specific token with three access levels:
- Read-only: With this, you can retrieve project information using the GET API call.
- Write-only: This serves as a project-specific API key, allowing you to create builds, snapshots, and upload resources to the project.
- Full-access: This serves as a project-specific read/write API key, allowing you to read build information, download snapshots, create builds and snapshots, and upload resources to the project.
Learn more about which feature works with which access levels.
Set PERCY_TOKEN as environment variable
You can run App Percy:
To learn about how to set your Percy token as an environment variable, see the relevant section.
Note
- App Percy works best when triggered automatically from your CI environment, but can also be run from your local development environment. This is helpful during the initial integration of App Percy.
- As of CLI version 1.26.7, the default configuration for all users involves automatically sending terminal logs to Percy to enhance support and improve services. However, we value your privacy and offer an option to opt out of this feature using an environment variable. You can use the following command to opt out:
export PERCY_CLIENT_ERROR_LOGS=false
Run App Percy locally
To run App Percy locally, set the PERCY_TOKEN environment variable using the export keyword as shown:
Alternatively, you can set the PERCY_TOKEN environment variable locally in a single line. For example:
Now you can run your tests locally.
Note
- When running in your local environment, it is recommended to set the
PERCY_BRANCHenvironment variable to “local” to prevent unintentionally overwriting of your project’smasterbaseline in App Percy. While not compulsory, this measure ensures the preservation of any baselines established by CI.
- If you don’t use the
PERCY_BRANCHvariable while you run local tests and you happen to be on the master branch, then it will result in setting the baseline for your project in App Percy as the master branch.
Run tests in parallel on BrowserStack App Infra
If you are using BrowserStack (App Automate) for your mobile device infra with Percy, then you can run multiple tests at the same time across various devices. This is called parallel testing. Parallel testing gives you the same benefits as running a multi-threaded application. More parallel tests speed up the time taken to complete a test suite.
BrowserStack App Automate plan supports running the number of parallel tests (5 during free trial). You can purchase more parallel as per your need. To learn more about parallel testing on Browserstack infra, visit here.
Run from your CI setup
To run App Percy from your CI workflow, update both the CI configuration file and the pipeline script. Learn more.
App Percy works best when integrated into your CI workflow, running continuously alongside your test suite. It seamlessly integrates with major CI providers and offers configurability for custom environments.
Note
We recommend to run App Percy via your CI workflow.
Other supported parameters
App Percy client libraries retrieve additional details from the environment they are running in, including the branch name, commit SHA, GitHub Pull Request number, and more. You can modify certain aspects of App Percy’s behavior by configuring these environment variables within your CI environment:
| Environment Variable | Description |
|---|---|
PERCY_TOKEN |
A Percy token is a project-specific, write-only API key. |
PERCY_BRANCH |
The branch in which the build is being executed. Default is the current git branch. |
PERCY_TARGET_BRANCH |
The branch for comparison. Default set to master. \n- If the App Percy build is associated to a GitHub Pull Request, setting this value will have no effect and the target branch will be automatically determined from the GitHub PR. To know more, read base build docs. |
PERCY_TARGET_COMMIT |
The full commit SHA of an existing App Percy build to be used as the reference baseline. To know more, read base build docs. |
PERCY_PULL_REQUEST |
The pull request number to link with the build, if any. |
PERCY_PARTIAL_BUILD |
Set to 1 to indicate the build is a partial build, and that it intentionally will be a subset of the snapshots from a full build. |
PERCY_ENABLE |
Set to 0 to prevent App Percy running in your CI environment. This can be useful to set conditionally if you want App Percy to be disabled in certain scenarios. |
PERCY_DEBUG |
Set to true to debug asset discovery and do not upload snapshots. |
PERCY_LOGLEVEL |
Set it to any of the following: ‘info’, ‘silent’, ‘warn’ or ‘debug’. |
PERCY_TMP_DIR |
Set an absolute path accessible locally where screenshots will be stored. |
PERCY_CLIENT_ERROR_LOGS |
Set to false to prevent the test script from sending logs to Percy. |
PERCY_COMMIT |
Set this to the Git commit SHA to ensure that visual tests and snapshots taken by Percy are correctly linked to a specific commit in the version control system. |
Note
With the latest version of @percy/agent, any of the environment variables defined on this page can be specified within a .env file in current working directory.
PERCY_TOKEN access levels
| Components of Feature | Read | Write | Full |
|---|---|---|---|
| Synchronous Comparison Results | No | No | Yes |
| Percy Screenshot | No | Yes | Yes |
| Percy Snapshot | No | Yes | Yes |
| Upload screenshots | No | Yes | Yes |
| CI Integration | No | Yes | Yes |
| API Reference - GET | Yes | No | Yes |
| API Reference - PUT/POST | No | Yes | Yes |
- Every feature that uses the Percy Screenshot and Percy Snapshot commands will have the same access, except for Synchronous CLI.
- We recommend using the ‘Write’ access mode for CI integration.
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