A Provider is responsible for performing flag evaluation, they can be as simple as an interface for a key value store, or act as an abstraction layer for a more complex evaluation system. Only one Provider can be registered at a time, and OpenFeature will no-op if one has not been defined. Before writing your own Provider, it is strongly recommended to familiarize yourself with the OpenFeature spec.
In this tutorial I will demonstrate the steps taken to create a new Provider whilst conforming to the OpenFeature spec using a simple flag implementation. The flag evaluation will be handled by a simple JSON evaluator and flag configurations will be stored as environment variables.

The following section describes how the flag evaluator portion of this project has been constructed, to skip to the Provider specific implementations, click here.

A Hook taps into one or more of the flag evaluation's lifecycle events (before/after/error/finally) to perform the same action at that point for every evaluation. In this blog post, we'll look into what it takes to create an OpenFeature hook in Go that verifies that the return value is a valid hex color.

Open Feature Announcement Blog​

• OpenFeature feature flag project applies for CNCF sandbox project status
• Dynatrace with industry consortium submits OpenFeature standard as CNCF sandbox project
• OpenFeature, With Contributions From eBay, Submitted to CNCF’s Sandbox Program

I've recently been involved¹ in OpenFeature, an effort to define a standard API and SDK for feature flagging. At first glance, you might wonder whether feature flagging needs a standard. It's just a function call and an if statement, right? Well, no, not really. I'll explain why, and then talk about some of the benefits that I hope OpenFeature will bring to the space.

The Feature Flagging iceberg​

When I talk to people about adopting feature flags, I often describe feature flag management as a bit of an iceberg. On the surface, feature flagging seems really simple, almost trivial. You call a function to find out the state of a flag, and then you either go down one code path, or the other. However, once you get into it turns out that there's a fair bit of complexity lurking under the surface.

Organizations that begin using feature flags at any sort of scale quickly learn that they need some of that functionality lurking under the surface. This is why flag management platforms like LaunchDarkly and Split.io exist. Their value is not in providing a fancy if statement, it's in all those extra features lurking below the surface - a web-based management interface, the ability to perform controlled incremental rollout, permissions and audit trails, integration into analytics systems, and so on.