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Automate Chromatic with Azure Pipelines

Chromatic’s automation can be included as part of your multistage Azure Pipelines workflow with relative ease.

Setup

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

azure-pipelines.yml
trigger:
  - main

pool:
  vmImage: 'ubuntu-latest'

stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    jobs:
      - job: Chromatic
        variables:
          npm_config_cache: $(Pipeline.Workspace)/.npm
        steps:
          - checkout: self
            displayName: "Get Full Git History"
            fetchDepth: 0
          - task: NodeTool@0
            displayName: "Install Node.js"
            inputs:
              versionSpec: "20.12.2"
          - task: Cache@2
            displayName: "Install and cache dependencies"
            inputs:
              key: 'npm | "$(Agent.OS)" | package-lock.json'
              restoreKeys: |
                npm | "$(Agent.OS)"
              path: $(npm_config_cache)
          - script: npm ci
            condition: ne(variables.CACHE_RESTORED, 'true')
          - task: CmdLine@2
            displayName: "Run Chromatic"
            inputs:
              script: npx chromatic
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

We recommend saving the project token as a secret environment variable named CHROMATIC_PROJECT_TOKEN for security reasons. In your Azure pipeline configuration, forward it using the env option. When the Chromatic CLI is executed, it will read the environment variable automatically without any additional flags. Refer to the official Azure environment variables documentation to learn more about it.

Run Chromatic on specific branches

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

azure-pipelines.yml
# 👇 Event to trigger pipeline execution
trigger:
  branches:
    include:
      - main # 👈 Filters the execution to run only on the main branch
    exclude:
      - example

# 👇 Configures pipeline execution on pull requests
pr:
  branches:
    include:
      - main # 👈 Filters the execution to run only on the pull requests for the main branch
    exclude:
      - example
# Additional pipeline configurations

Read the official Azure conditional pipeline documentation.

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

Run Chromatic on large projects

Chromatic is prepared to handle large file uploads (with a limit of 5000 files, including stories and assets). If your project exceeds this limit, we recommend adjusting your pipeline and run the chromatic command with the --zip flag to compress your build before uploading it. For example:

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    # Job list
    jobs:
      - job: Chromatic
        displayName: "Run Chromatic"
        steps:
          # Other steps in the pipeline

          # 👇 Adds Chromatic as a step in the pipeline
          - task: CmdLine@2
            displayName: "Run Chromatic"
            inputs:
              # 👇 Runs Chromatic with the flag to compress the build output.
              script: npx chromatic --zip
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

Run Chromatic on monorepos

Chromatic can be run on monorepos that have multiple subprojects. Each subproject will need its own project token set as an environment variable.

Prerequisites

  1. Ensure that you’re in the correct working directory for the subproject.
  2. Have build-storybook npm script in the subproject’s package.json file OR explicitly name the script using the buildScriptName parameter and make sure the script is listed in the subproject’s package.json file.

If you’ve already built your Storybook in a separate CI step, you can alternatively point the action at the build output using the storybookBuildDir parameter.

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"

    # 👇 Adds Chromatic as a step in the pipeline
    jobs:
      # 👇 Runs Chromatic sequentially for each monorepo subproject.
      - job: Chromatic_Deploy_1
        displayName: "Publish Project 1 to Chromatic"
        steps:
          # Other steps in the pipeline
          - task: CmdLine@2
            displayName: "Publish Project 1 to Chromatic"
            inputs:
              script: cd packages/project_1 && npx chromatic
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN_1)
      - job: Chromatic_Deploy_2
        displayName: "Publish Project 2 to Chromatic"
        steps:
          # Other steps in the pipeline
          - task: CmdLine@2
            displayName: "Publish Project 2 to Chromatic"
            inputs:
              script: cd packages/project_2 && npx chromatic
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN_2)

Additional paralellization can be achieved when configuring your workflow to run Chromatic on multiple subprojects. Read the official Azure DevOps documentation.

Enable TurboSnap

TurboSnap is an advanced Chromatic feature implemented to improve the build time for large projects, disabled by default once you add Chromatic to your CI environment. To enable it, you’ll need to adjust your existing workflow and run the chromatic command with the --only-changed flag as follows:

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    # Job list
    jobs:
      - job: Chromatic_Deploy
        displayName: "Run Chromatic"
        steps:
          # Other steps in the pipeline

          # 👇 Adds Chromatic as a step in the pipeline
          - task: CmdLine@2
            displayName: "Run Chromatic"
            inputs:
              # 👇 Enables Chromatic's TurboSnap feature.
              script: npx chromatic --only-changed
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

TurboSnap is highly customizable and can be configured to fit your requirements. For more information, read our documentation.

Overriding Chromatic’s branch detection

If your Azure pipeline includes a set of rules for branches (e.g., renames the branch, creates ephemeral, or temporary branches) it can lead to unforeseen build errors.

In this case, you can adjust your workflow and include the --branch-name flag. This flag overrides Chromatic’s default branch detection in favor of the specified branch:

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    # Job list
    jobs:
      - job: Chromatic
        displayName: Run Chromatic
        steps:
          # Other steps in the pipeline

          # 👇 Adds Chromatic as a step in the pipeline
          - task: CmdLine@2
            displayName: Run Chromatic
            inputs:
              # 👇 Runs Chromatic with the --branch-name flag to override the baseline branch
              script: npx chromatic --branch-name=${YOUR_BRANCH}
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

Chromatic will now detect the correct branch and run your workflow. You can also apply this when fixing cross-fork UI comparisons.

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:

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    # Job list
    jobs:
      - job: Chromatic
        displayName: "Run Chromatic"
        steps:
          # Other steps in the pipeline

          # 👇 Adds Chromatic as a step in the pipeline
          - task: CmdLine@2
            displayName: "Run Chromatic"
            inputs:
              #👇Runs Chromatic with the flag to prevent pipeline failure
              script: npx chromatic --exit-zero-on-changes
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

Read our configuration reference documentation.

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 npx 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 Run 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. This means testing your main branch to ensure builds are passing. It’s important to note that baselines will not persist through branching and merging unless you test your main branch.

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.

Azure squash/rebase merge and the “main” branch

Azure’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:

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    # Job list
    jobs:
      - job: Chromatic
        displayName: "Run Chromatic"
        steps:
          # Other steps in the pipeline

          # 👇 Checks if the branch is main and runs Chromatic with the flag to accept all changes.
          - task: CmdLine@2
            displayName: "Run Chromatic and auto accept changes"
            condition: and(succeeded(), eq(variables['build.sourceBranch'], 'refs/heads/main'))
            inputs:
              script: npx chromatic --auto-accept-changes
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)
            # 👇 Checks if the branch is not main and runs Chromatic
          - task: CmdLine@2
            displayName: "Run Chromatic"
            condition: eq(variables['Build.Reason'], 'PullRequest')
            inputs:
              script: npx chromatic
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

Read our configuration reference documentation.

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:

azure-pipelines.yml
# Other configurations

# Pipeline stages
stages:
  - stage: UI_Tests
    displayName: "UI Tests"
    # Job list
    jobs:
      - job: Chromatic
        displayName: "Run Chromatic"
        steps:
          # Other steps in the pipeline

          # 👇 Option to skip the last build on target branch
          - task: CmdLine@2
            displayName: "Run Chromatic"
            inputs:
              script: npx chromatic --ignore-last-build-on-branch=my-branch
            env:
              CHROMATIC_PROJECT_TOKEN: $(CHROMATIC_PROJECT_TOKEN)

Read our configuration reference documentation.

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

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).

Sharing project tokens allows contributors and others to run Chromatic builds on your project, consuming your snapshot quota. They cannot access your account, settings, or accept baselines. This can be an acceptable tradeoff for open source projects that 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:

npx chromatic --skip 'renovate/**'

Read our configuration reference documentation.

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

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