Feature Toggles

[pihme]

Is your feature request related to a problem? Please describe.
We are using feature toggles more frequently now. But there currently is no standardized way to define a feature toggle.

This makes implementing a feature toggle for a certain feature take more effort than necessary.

Describe the solution you'd like

• Implement a template for feature toggles.
• Document how to add/use/test a feature toggle

Describe alternatives you've considered
Adding https://www.togglz.org/quickstart.html as a dependency. However, this doesn't integrate nicely with what we have already. Also it would add a number of transitive dependencies.

Additional context
Add any other context or screenshots about the feature request here.

[pihme]

Implementation Approach

• Add a new class FeatureToggleCfg as child of ExperimentalCfg
• Feature toggles are boolean settings pretty much copied from ConsistencyCheckCfg
• Add documentation to config templates, add JavaDoc comments to explain how to add a feature toggle

This assumes that feature toggles are only temporary (that's why it's under experimental configuration)

[npepinpe]

Looks good to me. What would that look like in practice?

zeebe:
  broker:
    experimental:
      features:
        myCoolFeature: false

or

zeebe:
  broker:
    experimental:
      flags:
        myCoolFeatureFlag: false

So all environment variables would also be something like ZEEBE_BROKER_EXPERIMENTAL_FLAGS_MYCOOLFEATUREFLAG or the likes?

[pihme]

Don't know yet. I guess we will finalize that in the review :-)