Expand CMS Feature Flag functionality to enable incremental feature launches to CMS Editors

[jilladams]

User Story or Problem Statement

AS A Product owner I WANT the ability to launch CMS features to a % of Editors or a short list of Editors before launching to 100% SO THAT I can verify the utility of a feature & its use before launching to everyone.

Background

What CMS can do today: CMS contains feature toggles, off or on by default. (docs)

How can incremental releases work today: We can, we believe, write custom code to hook into the toggle and enable the feature for a set of users or a specific role.

Bigger picture Considerations / Concerns:

• The current framework isn't going to be user friendly for % releases, and managing the FE implications. That will be a problem to solve.
• How feature toggles do / don't, or can/can't affect GraphQL queries
• How toggles can / should be used for what kind of changes -- e..g it's doable when adding a new field. But it's not really possible do if changing an existing field.
  • Sub-topic: how we think about changing existing fields, in general, as a content API. (Thread from Tim around the conceptual piece of "we need to remember to think about Drupal as a content API that we cannot/should not break" : https://dsva.slack.com/archives/C03LFSPGV16/p1697066681666959)
• How we think about the database aspect of Drupal, and what happens if we are prod-testing something with a group of users that will then need to change
• There's a module called "Feature Flags" that might be useful, but we'd need to better understand user stories.

FE considerations

GraphQL data structure for existing fields can be affected by changes, e.g. from a single value to a multivalue field. The Events checkbox rollback was an example of this sort of change taking place in conjunction with something behind a feature flag, where we didn't realize the potential for FE impact due to the field structure / db change.

Acceptance Criteria

• [ ] Define use cases for CMS feature flags
• [ ] Create a Product outline
• [ ] Open a CMS Collab Cycle Request

[jilladams]

@davidconlon re: the conversation around more CMS incremental launches, I think we need to do some legwork with the CMS team around this concept. In order to open a CMS Collab Cycle Request, we need a product outline first. I'm queueing this up for our next product sync to discuss, just planting the seed here, and we can discuss with Fran what makes sense re: how to move this idea forward or if now is the right time.