Set environment variables

Configure your environment variables to allow Percy builds to run seamlessly

Percy integrates with your tests using both Percy and BrowserStackSDK. To establish this integration, choose the appropriate SDK and refer to the following section accordingly:

BrowserStack SDK
Percy SDK

To seamlessly integrate your visual and functional testing processes for your website, execute your Percy tests on BrowserStack’s Automate. If you’re already an Automate user and wish to explore Percy, you can do so as well. Leveraging BrowserStack SDK for running your tests fulfills all requirements.

Supported parameters

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 Percy’s behavior by configuring these environment variables within your CI environment:

Environment Variable	Description
`PERCY_BRANCH`	The branch in which the build is being executed. Default is the current git branch.
`PERCY_PULL_REQUEST`	The pull request number to link with the build, if any.
`PERCY_PARALLEL_TOTAL`	The total number of parallel builds to expect. \n- In most setups this is automatically discovered and does not need to be set. To know more, read Parallel test suites.
`PERCY_PARALLEL_NONCE`	A unique identifier used to group parallel builds. This can be any string that is shared between parallel runners, such as the CI build number. \n - In most setups this is automatically discovered and does not need to be set. To know more, read Parallel test suites.
`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.
`HTTP_PROXY`	Set http proxy that Percy cli should use in case you need to access internet over a corporate proxy.
`HTTPS_PROXY`	Set https proxy that Percy cli should use in case if you need to access internet over a corporate proxy In most cases setting only `HTTP_PROXY` should suffice, but if you have separate proxies for HTTP and HTTPS feel free to set both. The format for proxy’s is `http[s]://<username>:<password>@<domain.com>:<port>/` [`username` and `password` is optional].
`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.
`PERCY_GZIP`	Set this to `true` to potentially optimize resource size within the 25 MB threshold limit. The default is set to `false`.
`PERCY_DO_NOT_USE_CAPTURED_COOKIES`	Set this to `true` to stop the use of auto-captured cookies. The default is set to `false`.

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 a 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 Percy:

To learn about how to set your Percy token as an environment variable, see the relevant section.

Note

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 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 Percy locally

To run Percy locally, set the PERCY_TOKEN environment variable using the export keyword as shown:

Copy

Alternatively, you can set the PERCY_TOKEN environment variable locally in a single line. For example:

Copy

Now you can run your tests locally.

Note

When running in your local environment, it is recommended to set the PERCY_BRANCH environment variable to “local” to prevent unintentionally overwriting of your project’s master baseline in Percy. While not compulsory, this measure ensures the preservation of any baselines established by CI.
If you don’t use the PERCY_BRANCH variable 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 Percy as the master branch.

Run from your CI setup

To run Percy from your CI workflow, update both the CI configuration file and the pipeline script. Learn more.

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 Percy via your CI workflow.

Supported parameters

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 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 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_PARALLEL_TOTAL`	The total number of parallel builds to expect. \n- In most setups this is automatically discovered and does not need to be set. To know more, read Parallel test suites.
`PERCY_PARALLEL_NONCE`	A unique identifier used to group parallel builds. This can be any string that is shared between parallel runners, such as the CI build number. \n - In most setups this is automatically discovered and does not need to be set. To know more, read Parallel test suites.
`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 Percy running in your CI environment. This can be useful to set conditionally if you want 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’.
`HTTP_PROXY`	Set http proxy that Percy cli should use in case you need to access internet over a corporate proxy.
`HTTPS_PROXY`	Set https proxy that Percy cli should use in case if you need to access internet over a corporate proxy In most cases setting only `HTTP_PROXY` should suffice, but if you have separate proxies for HTTP and HTTPS feel free to set both. The format for proxy’s is `http[s]://<username>:<password>@<domain.com>:<port>/` [`username` and `password` is optional].
`PERCY_NETWORK_IDLE_WAIT_TIMEOUT`	This is maximum amount of time Percy cli’s resource discovery browser would wait for networkIdleTimeout to hit. This is defaulted to 30000ms [ 30 sec ].
`PERCY_PAGE_LOAD_TIMEOUT`	This is maximum amount of time Percy cli’s resource discovery browser would wait for page to load. This is defaulted to 30000ms [ 30 sec ].
`PERCY_SKIP_UPDATE_CHECK`	Set to true to skip CLI update checks we queryapi.github.com for newer CLI releases tags, if this env is not set false.
`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.
`PERCY_DO_NOT_CAPTURE_RESPONSIVE_ASSETS`	Set this to `true`, and it will not capture responsive assets like images for that page. The default is set to `false`.
`PERCY_EXIT_WITH_ZERO_ON_ERROR`	Set this to `true`, and this will exit with code 0 for any Percy-related errors, and the error logs will be available. The default is set to `false`.
`PERCY_GZIP`	Set this to `true` to potentially optimize resource size within the 25 MB threshold limit. The default is set to `false`.
`PERCY_DO_NOT_USE_CAPTURED_COOKIES`	Set this to `true` to stop the use of auto-captured cookies. The default is set to `false`.
`RESPONSIVE_CAPTURE_SLEEP_TIME`	Set this to an integer time in seconds to explicitly wait after each resize if you notice your webpage is not loading properly at certain widths. The default value is 0. Learn more.

Note
With the latest version of @percy/cli, 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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