Research: Feature Flags

[thisthat]

Goal

Research how we can make use of feature flags to hide new features of the Lifecycle Controller.

Technical details

OpenFeature is a CNCF project that solves feature flagging in a vendor agnostic fashion with a reference implementation for a FF provider. We should look into the project and check how we can make use of it.

Acceptance Criteria

• Evaluation at KeptnApp level should be enabled only when the FF evaluation-app is true.

DoD

• A PoC with some features behind feature flags.

References

• https://github.com/open-feature
• https://docs.openfeature.dev/
• https://docs.openfeature.dev/docs/tutorials/overview
• https://github.com/open-feature/flagd
• https://github.com/open-feature/go-sdk

[RealAnna]

During a one day hackaton we had the chance to test and research OpenFeature for KLT. PoC #585 has been created as reference. A feature flag to enable different level of span has been implemented.

Research outcomes

1. Operator installation is straightforward as in the docs
2. The sdk is quite easy to use and the changes required for the operator are only the followings:

• Enabling open feature with an annotation
• Initializing the provider in main
• Setting up client and context in the controllers where the feature is needed
• Preparing the config file with rules
• To setup rules one can use any kind of json operator, it is useful to rely on https://jsonlogic.com/operations.html
• As per today the only way to change a feature are either with rules or changing the default value
• PoC of setting the KLT operator's OpenTelemetry Collector URL at runtime
• PoC of enabling/disabling the metrics server endpoint at runtime

[RealAnna]

Proof of concept to add ff for metric server https://github.com/thschue/lifecycle-controller/pull/8

[RealAnna]

this research is completed