Automate Chromatic with BitBucket Pipelines

Chromatic’s automation can be included as part of your BitBucket pipeline workflow with relative ease.

Setup

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

# bitbucket-pipelines.yml

# A sample pipeline implementation
pipelines:
  default:
    # Other steps in the pipeline

      # 👇 Adds Chromatic as a step
    - step:
        name: 'Publish to Chromatic'
        caches:
          - node
        script:
          - yarn install
            # 👇 Runs Chromatic
          - yarn chromatic --project-token=$CHROMATIC_PROJECT_TOKEN
For extra security, add Chromatic's project-token as an environment variable. See the official BitBucket environment variables documentation.

Run Chromatic on specific branches

If you need to customize your workflow to run Chromatic on specific branches, adjust your pipeline like so:

# bitbucket-pipelines.yml

# A sample pipeline implementation
pipelines:
  default:
  # Other steps in the pipeline

  branches:
    # 👇 The example branch will display the message in the console instead of running Chromatic.
    main:
      - step:
         script:
           - yarn chromatic --project-token=$CHROMATIC_PROJECT_TOKEN
Read the official BitBucket conditional pipeline documentation.

Now your pipeline will only run Chromatic in the main branch.

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 pipeline 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 step will continue in such cases. For example:

# bitbucket-pipelines.yml

# A sample pipeline implementation
pipelines:
  default:
    # Other steps in the pipeline

      # 👇 Adds Chromatic as a step in the pipeline
    - step:
        name: 'Publish to Chromatic'
        # Other pipeline configuration
        script:
          - yarn install
            # 👇 Runs Chromatic with the flag to prevent pipeline failure 
          - yarn chromatic --project-token=$CHROMATIC_PROJECT_TOKEN --exit-zero-on-changes

When using --exit-zero-on-changes your pipeline execution still stop and fail if your Storybook contains stories that error. If you’d prefer Chromatic never to block your pipeline, you can use yarn 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 pipeline and the Publish to Chromatic step 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 “main” branch

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

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

BitBucket squash/rebase merge and the “main” branch

BitBucket’s squash/rebase merge functionality creates new commits that have no association to the branch being merged. If you are already using this option, then we will automatically detect this situation and bring baselines over (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 pipeline and include the --auto-accept-changes flag. For example:

# bitbucket-pipelines.yml

# A sample pipeline implementation
pipelines:
  default:
      # 👇 Checks if the branch is main and runs Chromatic with the flag to accept all changes.
    - step:
        name: 'Publish to Chromatic and auto accept changes'
        caches:
          - node
        script:
          - yarn chromatic --project-token=${CHROMATIC_PROJECT_TOKEN} --auto-accept-changes
  pull-requests:
    # 👇 Checks if the branch is not main and runs Chromatic
    your-branch:
      - step:
          name: 'Publish to Chromatic'
          script:
            - yarn chromatic --project-token=$CHROMATIC_PROJECT_TOKEN

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

If you want to test the changes introduced by the rebased branch, you can adjust your workflow and include a new step with the ignore-last-build-on-branch flag. For example:

# bitbucket-pipelines.yml

# A sample pipeline implementation
pipelines:
  default:
    # Other steps in the pipeline

      # 👇 Adds Chromatic as a step in the pipeline
    - step:
        name: 'Publish to Chromatic'
        # Other pipeline configuration
        script:
          - yarn install
            # 👇 Option to skip the last build on target branch
          - yarn chromatic --project-token=$CHROMATIC_PROJECT_TOKEN --ignore-last-build-on-branch=my-branch

Including the --ignore-last-build-on-branch flag ensures the latest build for the specific branch is not used as a baseline.

BitBucket pipelines and patch builds

If you’re creating a patch build in Chromatic to fix a missing pull request comparison, you’ll need to adjust your existing pipeline to the following:

# bitbucket-pipelines.yml


pipelines:
  pull-requests:
    # 👇 Will run as default for any branch not elsewhere defined
    '**':
      - step:
           # 👇 Adds Chromatic as a step in the pipeline
          name: 'Publish to Chromatic'
          caches:
            - node
          script:
              # 👇 Brings over the changes from the BitBucket repo
            - git fetch origin main:main
              # 👇 Option to update the build based on the changes obtained
            - yarn chromatic --project-token=$CHROMATIC_PROJECT_TOKEN --patch-build=$your-branch...main

Including the git command prior to running Chromatic prevents unwanted build errors when Chromatic retrieves the information from your BitBucket repo.

This is based on how BitBucket’s pipeline infrastructure handles cloning and branching. By default when the pipeline runs it will not do a full repository clone. Instead it will only fetch the current branch and omit all other existing ones.

Now you’ll be able to to see the UI changeset for PRs and perform UI Review as normal.

See the following BitBucket issue for a detailed explanation.

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 pipeline step).

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, Renovate 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 main or develop branch.

To skip builds for renovate branches, use the following:

chromatic --skip 'renovate/**'

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

chromatic --skip '@(renovate/**|your-custom-branch/**)'