percy on GitHub

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Covered in this doc

How to integrate Percy into static websites with the npm percy package
Configuring percy for testing locally and with CI

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Requirements

Node 10.0.0 or higher
A PERCY_TOKEN. Your token can be found on your Percy project settings page

Environment setup

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The percy package relies on the PERCY_TOKEN environment variable for authenticating and authorizing access to each project. The first step is to make your PERCY_TOKEN available in your environment.

On Linux and Mac, run:

$ export PERCY_TOKEN=aaabbbcccdddeeefff

On Windows, run:

$ set PERCY_TOKEN=aaabbbcccdddeeefff

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Important

Keep your PERCY_TOKEN secret. Anyone with access to your token can consume your account quota, though they cannot read data.

Generating snapshots

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If your generated static site exists in a directory called _site, simply run:

$ npx percy snapshot _site/

And that's it! Percy will create a build and snapshot by default all of the HTML files inside _site/.

For example:

$ npx percy snapshot _site/
Creating build...
percy has started.
serving static site at http://localhost:5339/
snapshot taken: 'http://localhost:5339/index.html'
snapshot taken: 'http://localhost:5339/404.html'
snapshot taken: 'http://localhost:5339/contact.html'
shutting down static site at http://localhost:5339/
stopping percy...
done! 
finalized build...

CI Configuration

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You can do the above steps locally for testing, but to get continuous visual integration for your static site you’ll need to run the npx percy snapshot _site/ command in CI.

You'll also want to make sure your PERCY_TOKEN is setup for that run. See the CI setup guides for how to securely set environment variables in your CI service.

For example, in CircleCI if we were using Hugo to generate your site, we can add these steps to .circleci/config.yml:

version: 2
jobs:
  build:
    docker:
      - image: cibuilds/hugo:latest
    working_directory: ~/hugo
    steps:
      - run: apk add --update nodejs npm             # install node, npm, and npx
      - checkout                                     # checkout the repository
      - run: hugo -v -d ~/hugo/public .              # build the site
      - run: npx percy snapshot ~/hugo/public # run Percy

Installing percy with npm

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The npx command has the benefit of being able to install and run any node package without having to worry about creating or maintaining a package.json, package-lock.json or similar file. However, the downside is that the percy package will be downloaded and installed every time. This can add time to your test runs.

When running Percy in CI (or even locally) consider using a package.json file to install and easily version percy. Using npm will install the latest version of percy locally and save the version in a package.json file. Both npm and npx are available in Node 8.2 or newer.

If you don't already have a package.json file, you can create one by running:

$ npm init

Next install the percy package.

$ npm install --save-dev percy

The npx command will then look for this local binary before downloading and installing a different version. A package.json file will also make it easier to use a specific version of percy.

With a package.json file added to your codebase, your CI setup can now benefit from installing a cached version of percy by running one command before running Percy.

$ npm install
$ npx percy snapshot _site/

CLI options

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--snapshot-files, -s

Glob or comma separated string of globs for matching the files to snapshot.

The default value is **/*.html,**/*.htm.

$ npx percy snapshot _site --snapshot-files _site/**/*.html,_docs/**/*.html

TIP: You can test your globs on globster.xyz

--ignore-files, -i

Glob or comma separated string of globs for ignoring the files to snapshot.

The default value is empty.

$ npx percy snapshot _site --ignore-files _old-site/**/*.html

--base-url, -b

If your static files are hosted in a sub-directory instead of the webserver root, you will need to provide the --base-url flag. The base URL must begin with a slash.

The default value is /.

$ npx percy snapshot _site/ --base-url /my-subdir

--network-idle-timeout, -t

The idle time (in ms) that percy will wait for assets to load before moving on to the next page. Your site will be hosted locally and then percy will visit each page. If your assets have not loaded by the time the timeout is reached, then your snapshots in Percy might not correctly render on our servers. Consider raising this time if you see this occur on your snapshots.

The default value is 50 (ms).

$ npx percy snapshot _site/ --network-idle-timeout 250

Additional configuration options

Additional widths and a minimum viewport height can be set via the percy.yml file.