How to use YML anchors with dynamic variables / parts?

Question

Hello people!

I'm using yml anchors in my pipelines already and wanted to clean it up even more.

Right now I've an anchor step like that:

- step: &build-frontend
  name: Build application and generate artifacts
  caches:
    - node
  script:
    - echo $DOTENV_STAGING | base64 --decode > .env
    - yarn
    - yarn build

This step just builds my frontend code with a given .env file I have saved as base64 encoded string on my pipeline deployment variables.

The problem now is, I want to use the exact same step with a different variable on production as well, in that case it must be $DOTENV_PRODUCTION. How can I accomplish this somehow?

I know I could overwrite the whole step but then I also do not have to use the anchors. ;-)

What would also work is using the deployment name in an if condition but unfortunately it looks like there is no variable in the default variables where I can get it from?

I lost my mind for some reason and can't find any good solution.

Or maybe there is something more elegant?

Nice to hear from you!

Thanks.

ktomk · Answer

@Ben as an alternative answer next to YAML anchors is to combine it with Merge Key Language-Independent Type for YAML™ Version 1.1 which allows to mix-in only the changing mapping with a base (definition).

Not so sure how well it works with arrays as it is about maps, here is an example which is working on Bitbucket Pipelines where I don't change a variable between two "same" steps, but the image name. That is linting the source-code with PHP 5.3 and then with PHP 7.4. Both steps are the same and only the image differs:

custom:
lint-php-5.3:
    - step: &lint-php53
        image: php:5.3
script:
          - lib/pipelines/lint.sh
  # ...
  lint-php-7.4:
    - step: &lint-php74
      <<: *lint-php53
      image: php:7.4
  lint-php:
    - step: *lint-php53
    - step: *lint-php74

Note the `<<:`  part. Ignore in this example it's not anchoring from `definitions`, it should be similarly possible, here in the example it's just all self-contained within the custom pipelines.

This is a real-life example, you can find the full file here: https://github.com/ktomk/pipelines/blob/master/bitbucket-pipelines.yml#L14-L40 (the highlighting will change over time and appear misplaced in the future).

ktomk · Answer

Is it an option for you to (better/more) divide the build of the package from the deployment itself?

Ben_p799ei · Answer

Unfortunately this is not possible in my case. The problem is that I've more than one step within a set of parallel steps where I would have to use the deployment: thing in pipelines.

And using it is only supported once for a pipeline.

Multiple usage is not supported.