Add impact analysis in GitHub

danger

For existing users, the dbt-action is no longer maintained and will be deprecated eventually. Atlan strongly recommends migrating to the atlan-action. Refer to How to migrate from dbt to Atlan action to learn more and complete the migration.

If you have ever changed a dbt model only to find out later that it broke a downstream table or dashboard, Atlan provides a GitHub Action to help you out.

This action places Atlan's impact analysis right into your pull request. So, you can view the potential downstream impact of your changes before merging the pull request.

Prerequisites

1. Before running the action, you will need to create an Atlan API token.
2. You will also need to assign a persona to the API token and add a metadata policy that provides the requisite permissions on assets for the Atlan dbt action to work. For example, you can add the following permissions:
   • dbt - Read and Update
   • Materialized layer, such as Snowflake - Read and Update
   • Any downstream connections, such as Microsoft Power BI - Read only
3. When a pull request with changes to one or more dbt models is merged, the Atlan dbt action will link the pull request as a resource to the assets in Atlan. To ensure that the pull request is linked as a resource, you will need to assign the right persona with requisite permissions to the API token.
4. You will need to configure the default GITHUB_TOKEN permissions. Grant Read and write permissions to the GITHUB_TOKEN in your repository to allow the atlan-action to seamlessly add or update comments on pull requests. Refer to GitHub documentation to learn more.

Configure the action

To set up the Atlan action in GitHub:

1. Create repository secrets in your repository:
   • ATLAN_INSTANCE_URL with the URL of your Atlan instance.
   • ATLAN_API_TOKEN with the value of the API token.
2. Add the GitHub Action to your workflow:

   1. Create a workflow file in your repository - .github/workflows/atlan-dbt.yml.

   2. Add the following code to your workflow file:

      name: Atlan action
      
      on:
        pull_request:
          types: [opened, edited, synchronize, reopened, closed]
      
      jobs:
        get-downstream-impact:
          name: Get Downstream Assets
          runs-on: ubuntu-latest
          steps:
            - name: Run Action
              uses: atlanhq/atlan-action@v1
              with:
                GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
                ATLAN_INSTANCE_URL: ${{secrets.ATLAN_INSTANCE_URL}}
                ATLAN_API_TOKEN: ${{secrets.ATLAN_API_TOKEN}}

Test the action

After you've completed the configuration above, create a pull request with a changed dbt model file to test the action. You should see the Atlan GitHub action running and then adding comments in your pull request:

• The GitHub workflow will add and update a single comment for every file change.
• The impacted assets in the comment will be displayed in a collapsible section and grouped by source and asset type.
• The comment will include some metadata for your impacted assets - such as descriptions, owners, and linked glossary terms.
• View the impacted assets in Atlan or open the source URL - for example, view an impacted Looker dashboard directly in Looker.
• Once you have merged the pull request, it will be added as a resource to the dbt model and its materialized assets. You can view the linked pull request from the Resources tab of the asset sidebar.

For example:

Inputs

Name	Description	Required
GITHUB_TOKEN	For writing comments on PRs to print downstream assets	true
ATLAN_INSTANCE_URL	For making API requests to the user's tenant	true
ATLAN_API_TOKEN	For authenticating API requests to the user's tenant	true
DBT_ENVIRONMENT_BRANCH_MAP	For mapping the GitHub branch with a specific dbt environment	false
IGNORE_MODEL_ALIAS_MATCHING	For turning off matching aliases using this variable	false

Troubleshooting the action

Why does the action fetch a model from an incorrect environment?

If there are multiple dbt models with the same name but across different environments in your Atlan instance, the action may fetch an incorrect model. In order to ensure that the action fetches a model from the right environment, you can map the GitHub branch with a specific dbt environment. This will allow the Atlan GitHub action to parse lineage for that specific environment.

For example, you can provide the mapping in this format - branch name : dbt environment name

jobs:
  get-downstream-impact:
    name: Get Downstream Assets
    runs-on: ubuntu-latest
    steps:
      - name: Run Action
        uses: atlanhq/atlan-action@v1
        with:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
          ATLAN_INSTANCE_URL: ${{secrets.ATLAN_INSTANCE_URL}}
          ATLAN_API_TOKEN: ${{secrets.ATLAN_API_TOKEN}}
+         DBT_ENVIRONMENT_BRANCH_MAP: |
+           main: dbt-prod
+           beta: dbt-test

Why does the action fetch a model by its alias and not model name?

By default, the action checks if there is an alias defined for a dbt model in the code and looks for the relevant asset in Atlan using that alias. To turn off matching aliases for your dbt models, you can set the IGNORE_MODEL_ALIAS_MATCHING input to true.

For example:

jobs:
  get-downstream-impact:
    name: Get Downstream Assets
    runs-on: ubuntu-latest
    steps:
      - name: Run Action
        uses: atlanhq/atlan-action@v1
        with:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
          ATLAN_INSTANCE_URL: ${{secrets.ATLAN_INSTANCE_URL}}
          ATLAN_API_TOKEN: ${{secrets.ATLAN_API_TOKEN}}
+         IGNORE_MODEL_ALIAS_MATCHING: true