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Continuous Integration

Adding Happo to your Continuous Integration setup is the best way to catch visual regressions early. Happo will compare your PRs with the base branch and let you know exactly what has changed in your UI.

Happo status on a GitHub pull request Example of a Happo status posted to a GitHub pull request.

Setup​

The instructions on this page apply to all integrations except the Cypress and Playwright integrations. Refer to the Cypress integration page and the Playwright integration page for instructions on how to integrate with CI there.

Since a lot of projects follow a pull-request/merge-request model, Happo provides a unified CLI command that automatically detects CI environments. The main happo CLI command will:

  1. Figure out the right baseline report to compare with, starting at the merge base for the pull request branch
  2. Create a Happo report for the current HEAD commit
  3. Compare the baseline report with the new report
  4. If allowed to, post back a status to the commit/PR

The CLI auto-detects the following CI environments:

  • GitHub Actions
  • Circle CI
  • Travis CI
  • Azure DevOps

If your CI environment is not listed here or if you run into any issues, please reach out to support@happo.io and we will help you get things set up.

GitHub Actions​

This script knows about the GitHub Actions build environment, assuming a PR based model. To run it, configure your workflow file to run the happo command. Here's an example:

.github/workflows/happo.yml
name: Happo CI

on:
  push:
    branches: [main]
  pull_request:

jobs:
  happo:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha || github.ref }}
          fetch-depth: 100
      - name: Fetch main branch
        if: github.ref != 'refs/heads/main'
        run: git fetch origin main:main
      - uses: actions/setup-node@v4
      - run: npm ci
      - run: npx happo
        env:
          HAPPO_API_KEY: ${{ secrets.HAPPO_API_KEY }}
          HAPPO_API_SECRET: ${{ secrets.HAPPO_API_SECRET }}

Make sure that the workflow is configured to run on pushes to your default branch. This will ensure that baselines exist for PR builds to compare against.

Circle CI​

The happo script knows about the CircleCI build environment, assuming a PR based model. To run it, configure .circleci/config.yml to run the happo command. Something like this:

.circleci/config.yml
jobs:
  build:
    docker:
      - image: cimg/node:lts
    steps:
      - checkout:
          method: full

      - run:
          name: happo
          command: npx happo

The happo command assumes your PRs are based off of the main branch. If you're using a different default branch, you can set the --baseBranch argument.

.circleci/config.yml
jobs:
  build:
    docker:
      - image: cimg/node:lts

    steps:
      - checkout:
          method: full

      - run:
          name: happo
          command: npx happo --baseBranch origin/main

Azure DevOps​

The happo script knows how to resolve variables from Azure Pipelines. It can be used with pull requests and regular pushes. To run it, configure azure-pipelines.yml to run the happo command.

In the example below the HAPPO_API_KEY and HAPPO_API_SECRET environment variables are populated from two user-defined secret variables.

azure-pipelines.yml
trigger:
  - main
pool:
  vmImage: ubuntu-latest
steps:
  - task: NodeTool@0
    inputs:
      versionSpec: '22.x'
    displayName: 'Install Node.js'
  - script: |
      npm ci
      npx happo
    displayName: 'Install dependencies and run Happo'
    env:
      HAPPO_API_KEY: $(happoApiKey)
      HAPPO_API_SECRET: $(happoApiSecret)

The trigger is set to run for pushes to the main branch. You'll have to replace this if you are using a different default branch. To trigger builds for pull requests, you can use a branch policy for the main branch.

Travis CI​

This script knows about the Travis build environment, assuming a PR based model. To run it, configure .travis.yml to run the happo command:

.travis.yml
language: node_js
script:
  - npx happo

The happo command assumes that your PRs are based off of the main branch. If you're using a different default branch, you can set the --baseBranch argument.

.travis.yml
language: node_js
script:
  - npx happo --baseBranch origin/master

Generic CI​

If you are using a different CI service, you'll have to set a few different CLI arguments when invoking the happo command:

  • --beforeSha - the SHA of the baseline commit
  • --afterSha - the SHA of the current HEAD
  • --link - a URL that links back to the change (further instructions)

Posting build statuses​

Your Happo account can be configured to post build statuses to your PRs/commits. Happo currently integrates with GitHub, Bitbucket, and Azure DevOps. See specific instructions for the different providers below.

GitHub​

The instructions in this section only work if you are using github.com or the on-premise version of happo.io. If you're using a local GitHub Enterprise setup, there is an alternative solution described in the next section

Step 1: Install Happo GitHub app​

First you need to install the Happo GitHub App in the repository/repositories you want to run Happo in.

Installing the Happo GitHub App Installing the Happo app at https://github.com/apps/happo

Step 2: Connect with repository​

Once you have the Happo GitHub app installed, you need to connect/activate the right repository with your Happo account on the GitHub integration page on happo.io. Once you're done with that, you're all set to have Happo automatically post statuses on your PRs/commits.

Connecting repository with the Happo account Activating the GitHub repository at https://happo.io/github-integration

Happo build statuses​

Here's what it looks like when Happo posts a status on a pull request:

Happo status posted on a commit on github

If there is a diff, the status will be set to failure. To manually flip this to a success status, just go to the Happo comparison page (linked to by the "Details" link next to the Happo status) and click the Accept button at the top.

Accepting diffs

The status over on github.com will then change to success (green) for the PR/commit.

Happo status manually accepted cross-posted to github

If there are no diffs, the status is automatically set to success.

Posting statuses without installing the Happo GitHub App​

If you for some reason can't install the Happo GitHub App (e.g. when using GitHub Enterprise) you can still get the Happo status posted to your PR -- as a comment on the pull request. To get this working, you have to provide the Happo CI script with either a HAPPO_GITHUB_TOKEN auth token or HAPPO_GITHUB_USER_CREDENTIALS containing a username and a personal access token.

If you are using GitHub Actions, the easiest thing is to set the HAPPO_GITHUB_TOKEN based on the automatically provided secrets.GITHUB_TOKEN variable.

env: HAPPO_GITHUB_TOKEN=${{ secrets.GITHUB_TOKEN }}

If you are not in a GitHub Actions environment, you can instead use a personal access token:

HAPPO_GITHUB_USER_CREDENTIALS="trotzig:21A4XgnSkt7f36ehlK5"

Here's a guide from github.com on how to generate the personal token.

The environment variable must contain both the username of the profile and the personal access token, separated by a colon.

If you're using GitHub Enterprise, apart from defining the environment variable you also need to add githubApiUrl to .happo.js.

Bitbucket​

To allow Happo to post build statuses to your Bitbucket repo, you need to configure Happo with an API token or a Repository access token.

Step 1: Generate a token​

Alternative A: API Token​

On your API tokens page for your profile, generate a scoped API token with the scope read:repository:bitbucket.

Generating a scoped Bitbucket API token Generating a scoped Bitbucket API token through the Bitbucket UI

Alternative B: Repository access token​

On your repository settings page, go to Security > Access tokens. Generate a token with the Repositories > Read scope.

Generating a repository access token Generating a repository access token through the Bitbucket UI

Step 2: Fill in form at Happo​

Once you have the API token, you can go to the Bitbucket integration page on happo.io and fill out the form. If you have an API token, set the email field to your bitbucket account email. If you have a repository access token, set the email field to x-token-auth. When you're done with filling out the form and the connection is working, you're all set to have Happo automatically post statuses on your PRs/commits.

Happo build statuses​

Here's what it looks like when Happo posts a status on a pull request:

Happo status posted on a bitbucket commit

If there is a diff, the status will be set to failure. To manually flip this to a success status, just go to the Happo comparison page (linked to from the status) and accept the diffs.

Accepting diffs

The status over on bitbucket.org will then change to success (green) for the PR/commit. If there are no diffs, the status is automatically set to success.

Azure​

Step 1: Generate a Personal Access Token (PAT)​

To authorize Happo to post statuses to your PRs/commits, you need to generate an Personal Access Token.

Generating an Azure Personal Access Token Generating a Personal Access Token through the Azure UI

Set the "Code" scope to Read and Status. We need the read scope to figure out the right baseline reports to use. The status scope is used when posting build statuses to PRs.

Step 2: Fill in form at Happo​

Once you have the PAT, you can go to the Azure integration page on happo.io and fill out the form. Once you're done with that, you're all set to have Happo automatically post statuses on your PRs/commits.

Happo build statuses​

Here's what it looks like when Happo posts a status on a pull request:

Happo status posted on an azure PR

If there is a diff, the status will be set to failure. To manually flip this to a success status, just go to the Happo comparison page (linked to from the status) and accept the diffs.

Accepting diffs

The status over on Azure DevOps will then change to success (green) for the PR/commit. If there are no diffs, the status is automatically set to success.

Email notifications​

You can set up the CI integration to send email notifications when comparison reports are ready. Set the --notify CLI argument to one or more (comma-separated) email addresses and emails will be sent from Happo when results are available.

npx happo --notify user@example.com

If you want to send the email to the person responsible for the change/PR that triggered the Happo tests, you can do that via a git show one-liner. Here's an example for GitHub Actions:

.github/workflows/happo.yaml
- run: npx happo --notify $(git show -s --format=%ae HEAD)

Multiple recipients​

Use a comma-separated list of email addresses to send the notification to several recipients:

npx happo --notify user@example.com,service-account@mycompany.com

The --link argument is used to contextualize the report. Happo will link back to the --link URL whenever the report is shown. Some good examples of links to use:

  • A URL that leads to the pull request/merge request that started the build
  • A link to the commit associated with the build