Create DRY Bitbucket Pipelines scripts by using YAML Anchors and Aliases

If you are using a CI you know the benefits of scripting and automation. Then why repeat yourself in your bitbucket-pipelines.yml when you can write a step once and use multiple times.

Photo by Max Hermansson on Unsplash

An anchor defines a chunk of steps to be used elsewhere — it is represented by a & symbol

An alias is used to call an anchor from elsewhere — it is represented by a *

Simple example

definitions: 
  steps:
    - step: &test
        name: Test app
        script:
          - yarn
          - yarn test
    - step: &build
        name: Build app
        script:
          - yarn
          - yarn build

pipelines:
  pull-requests:
    '**':
      - step: *test
  branches:
    develop:
      - step: *test
      - step: *build
    master:
      - step: *test
      - step: *build

Customising the step

You can override values when calling an anchor with << like in the example below.

pipelines:
  branches:
    develop:
      - step: *test
      - step: *build
    master:
      - step: *test
      - step: 
          <<: *build
          name: Building Master

And we’ve done! 🙌

In the simple examples above we aren’t being all that much more efficient but with a longer real world example the benefits are far greater — I hope this helps.