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Feature Flags are just if Statements, Right?

· 3 min read
Adam Gardner

Most feature flag explainers begin by explaining that feature flags are glorified if statements. While that’s true (to a point), feature flags wouldn’t be as versatile or as popular as they are, if that’s all they were. Indeed, you wouldn’t need a feature flag – you could easily achieve the same thing with an environment variable.

In code, the above would look like this:

if isPremiumMember {
  return v2
} else {
  return v1
}

Now try modelling this in code:

  • If user is premium and located in Europe = v2 (purple)
  • If user is premium and located in the US = v3 (red)
  • If user is premium and located in Australia = v4 (orange)
  • Everyone else gets v1 (green)

That’s 2 variables. Imagine how many variations a real system has. Now imagine trying to update these conditions in real time, without a redeployment.

The real power of feature flags:

  • They can be as simple or as complex as you like (this makes getting started easy with plenty of room to grow and expand)
  • Separation of concerns: Allows you to deploy without releasing (place all new features behind flags and disable them).
  • Shortcut to continuous delivery: If you can deploy anything at any time with zero risk, why not do it?
  • Separation of responsibilities: Product managers take responsibility of feature flags, leaving DevOps teams to deal with their area of responsibility.

So, are Feature Flags if Statements?​

No, feature flagging is so much more powerful and dynamic than environment variables or if statements. But if you’re already using if statements, you already have enough knowledge to take your environment variables and if statements to the next level with feature flags.

If you’re stuck on the environment variable + if statement metaphor, feature flags are a very complex if statement that you can target, update, toggle and gain observability over, in real time without a re-deployment.

Where Do I Start?​

Start with the OpenFeature hands-on tutorials. These tutorials are provided by Killercoda, a third-party in-browser learning platform.

All tutorials are free to use and the tutorial source code is open.

1: OpenFeature Demo​

Never encountered feature flags? This is the 30,000ft view showing the power and versatility of feature flags.

Start here.

2: An Open Source Feature Flag Backend​

Decided to adopt feature flags? You will need a flag "backend" evaluation engine. Choose a vendor or code your own?

Start your journey with the open source flagd solution.

3. Instrument Your Application​

Whether you've chosen to use flagd, gone with a vendor solution, or developed a custom OpenFeature-compliant in-house solution, by now your backend flag evaluation infrastructure is running. It is time to instrument your application!

The Five minutes to feature flags tutorial walks through how to instrument an application in an OpenFeature-compliant way.

4: Feature Flags on Kubernetes?​

Are you Kubernetes-native and want to manage and use feature flags entirely on Kubernetes?

The Operator tutorial demonstrates how to leverage Custom Resources to manage feature flags via GitOps and make feature flags available to your pods via annotations.