Automate Chromatic with a custom provider

Chromatic automation can be included as part of any CI provider with relative ease. We’re here for you. Contact us through our in-app chat for further assistance.

Setup

To integrate Chromatic with your existing CI provider, you’ll need to add the following:

# your-workflow

- run:
    command: npm install # Installs dependencies
- run:
    command: npm test # Run your unit tests
- run:
    # 👇 Publish Storybook and run visual tests in Chromatic
    command: npm run chromatic --project-token=CHROMATIC_PROJECT_TOKEN
For extra security, add Chromatic's project-token as an environment variable. See your provider's documentation for reference.

Run Chromatic on specific branches

Depending on the CI provider you’re using, running Chromatic from a specific branch will not be a issue. Refer to your CI documentation for further details.

UI Test and UI Review

UI Tests and UI Review rely on branch and baseline detection to keep track of snapshots. We recommend the following configuration.

Command exit code for “required” checks

If you are using pull request statuses as required checks before merging, you may not want your build to fail if test snapshots render without errors (but with changes). To achieve this, pass the flag --exit-zero-on-changes to the chromatic command, and your job will continue in such cases. For example:

# your-workflow

# Your custom CI implementation 

- run:
    # 👇 Runs Chromatic with the flag to prevent stage failure
    command: npm run chromatic --project-token=CHROMATIC_PROJECT_TOKEN
Read our official CLI documentation.

When using --exit-zero-on-changes your job will still stop and fail if your Storybook contains stories that error. If you’d prefer Chromatic never to block your job, you can use npm run chromatic || true.

Re-run failed builds after verifying UI test results

Builds that contain visual changes need to be verified. They will fail if you are not using --exit-zero-on-changes. Once you accept all the changes, re-run the workflow and the job will pass.

If you deny any change, you will need to make the necessary code changes to fix the test (and thus start a new build) to get Chromatic to pass again.

Maintain a clean “master” branch

A clean master branch is a development best practice and highly recommended for Chromatic. In practice, this means ensuring that test builds in your master branch are passing.

If the builds are a result of direct commits to master, you will need to accept changes to keep master clean. If they’re merged from feature-branches, you will need to make sure those branches are passing before you merge into master.

Squash/rebase merge and the “master” branch

We use GitHub, GitLab, and Bitbucket APIs respectively to detect squashing and rebasing so your baselines match your expectations no matter your Git workflow (see Branching and Baselines for more details).

If you’re using this functionality but notice the incoming changes were not accepted as baselines in Chromatic, then you’ll need to adjust the chromatic command and include the --auto-accept-changes flag. For example:

# your-workflow

# Your custom CI implementation 

- run:
    # 👇 Checks if the current branch is not master and runs Chromatic
    if: branch != master
      command: npm run chromatic --project-token=CHROMATIC_PROJECT_TOKEN 
    # 👇 Checks if the current branch is master and accepts all changes in Chromatic
    else:
      command: npm run chromatic --project-token=${CHROMATIC_PROJECT_TOKEN} --auto-accept-changes 
Read our official CLI documentation.

Including the --auto-accept-changes flag ensures all incoming changes will be accepted as baselines. Additionally you’ll maintain a clean master branch.

Run Chromatic on external forks of open source projects

You can enable PR checks for external forks by sharing your project-token where you configured the Chromatic command (often in package.json or in the workflow).

There are tradeoffs. Sharing project-token‘s allows contributors and others to run Chromatic. They’ll be able to use your snapshots. They will not be able to get access to your account, settings, or accept baselines. This can be an acceptable tradeoff for open source projects who value community contributions.

Skipping builds for certain branches

Sometimes you might want to skip running a build for a certain branch, but still have Chromatic mark the latest commit on that branch as “passed”. Otherwise pull requests could be blocked due to required checks that remain pending. To avoid this issue, you can run chromatic with the --skip flag. This flag accepts a branch name or glob pattern.

One use case for this feature is skipping builds for branches created by a bot. For instance, Dependabot automatically updates a projects dependencies. Although some dependencies can result in UI changes, you might not find it worthwhile to run Chromatic for every single dependency update. Instead, you could rely on Chromatic running against the master or develop branch.

To skip builds for dependabot branches, use the following:

chromatic --skip 'dependabot/**'

To apply this to multiple branches, use an “extended glob”. See picomatch for details.

chromatic --skip '@(renovate/**|dependabot/**)'