Can naming feature flags be hard?
Yes. Just like variables in programming, naming feature flags can get tricky if you don't follow a naming standard. When feature flags don't have good names, it can be difficult for people using them to remember what they do. In this article, we'll see a few naming conventions we can use for feature flags.
A Quick Refresher on Feature Flags
Feature flags (or feature toggles) are controls that allow you to turn features in your software on or off without having to redeploy your code. Using feature flags, you can separate deployments from releases by deploying code and keeping it disabled until you're ready to turn it on. They have many use cases, such as canary releases, A/B testing, and even infrastructure migrations. With so many use cases, you can start to see how a naming convention can come in handy.
Conventions
General Rule
A feature flag's name should be descriptive enough to explain what it does; its function should be obvious to anyone who looks at it. That said, don't be afraid to give your feature flags long names. It's better for a feature flag to have a lengthy, descriptive name than a short, confusing one. Let’s take an example.
Imagine that an online Markdown editor software has a new spellcheck feature in development. The developers want to hide it behind a feature flag and turn it on when it's ready for release. They name the feature flag:
rollout_text_editor_spellchecker
The word "rollout" tells us that when the developers turn the flag on, it will release the spellchecker feature to users. The "text_editor_spellchecker" part is self-explanatory. This feature flag's name is pretty descriptive, and anybody using it is unlikely to be confused about what it does. Let's see what other information we can add to feature flag names to make them more detailed.
Team name
Considering the size of development teams nowadays and the fact that non-development teams (like marketing and product management) can be in charge of toggling feature flags, it can be helpful to prefix a feature flag’s name with the name of the team responsible for toggling it. Here's an example using our spellchecker flag from before:
naming structure:
teamname_flagfunction
flag name:
engineering_rollout_text_editor_spellchecker
In this example, the prefix "engineering" in the flag's name indicates that the engineering team in the organization is responsible for toggling the flag. When people from other teams see this name, they'll immediately know who's in charge of the flag. Here's an example for the marketing team:
flag name:
marketing_simplified_signup_form
In this example, the marketing team is using A/B testing on a signup form to see if the company's product gets more users. They'll be responsible for toggling the flag for the experiment.
Flag Type
There are 4 main types of feature flags: release, experiment, ops, and permission. They all have defining characteristics, so it can be a good idea to include them in a feature flag’s name. Let’s apply this convention to our previous examples:
naming structure:
teamname_flagtype_flagfunction
flag name:
engineering_release_rollout_text_editor_spellchecker
flag name:
marketing_experiment_simplified_signup_form
Since the spellchecker feature is deployed but won't be released until it's ready, it's hidden behind a release flag. As for the signup form, it's hidden behind an experiment flag because the marketing team is running an A/B test on it.
You might have noticed that the names are significantly longer than they were before. I know I said you shouldn't be afraid to give your feature flags long names, but it's also nice to keep things balanced so that your flag names don't get too complex. Let's take a short detour to see how we can achieve this balance.
ConfigCat's Flag Hints and Tags
ConfigCat is a cloud-based feature management service that enables you to toggle features remotely, with options for user targeting and segmentation which you can use for A/B testing, canary releases, and more.
ConfigCat allows you to add hints to your feature flags, so you don’t forget what they do. You can also create tags for your feature flags so that they are easier to identify and organize. Here are our examples in ConfigCat's dashboard:
Using the team names and flag types as tags, you won't need to keep them in the flag names anymore. And as a bonus, you'll be able to filter your feature flags by their tags. Though the flag names are shorter, they're still verbose, and you can add more information about your flags thanks to hints.
That's all for our little detour. Let's get back to the conventions.
Longevity
If you want to indicate how long a feature flag is going to be used, you can add suffixes like "temp" and "perma" to its name. With this convention, you can easily spot a feature flag that is due for removal if you’re trying to clean up feature flags that are no longer in use. Let's see some examples:
naming structure:
teamname_flagtype_flagfunction_longevity
flag name:
sales_permission_enable_plagiarism_checker_for_user_perma
flag name:
engineering_release_rollout_text_editor_spellchecker_temp
We have a new example: a permission flag that the sales team can toggle for users who purchase the premium plagiarism checker feature. This flag will be there for as long as the app exists, so it gets "perma" in its name. The spellchecker feature is hidden behind a release flag, and since release flags are usually short-lived, the flag gets "temp" in its name.
Flag Creation Date
You can include a flag's creation date in its name as a timestamp to make auditing flags easier. You may use dates as criteria for evaluating what flags to remove. For instance, if a feature flag is old and turned off, it's a good sign that it's not in use anymore. Here's an example:
naming structure:
teamname_flagtype_flagfunction_longevity_creationdate
flag name:
engineering_release_rollout_text_editor_spellchecker_temp_051123
The date in the example is in the day-month-year format, meaning it was created on the 5th of November 2023. It's no secret that date formats can be confusing, but you're less likely to mix up dates if you select one date format for your projects.
Casing Styles
Here's a list of popular case styles and how they look:
Camel case - myCoolFeatureFlag
Kebab case - my-cool-feature-flag
Snake case - my_cool_feature_flag
Pascal case - MyCoolFeatureFlag
If you're using ConfigCat, you can choose camel, snake, or pascal case for your feature flag keys. As a bonus, you won't have to type out the name with the casing. Just give your feature flag a name, and ConfigCat will generate a key from it using the case style you chose.
Those are all the naming conventions we'll look at in this article. You probably understand their usefulness by now, but let's go over a few more points to see just how important they are.
Avoiding Costly Mistakes
There are quite a few things that could go wrong when teams do not use a naming convention for their feature flags:
Someone could accidentally turn on a feature that is not ready for production. Such a mistake can negatively impact the software's users and cause the organization financial losses.
Someone could turn on a retired feature because its flag name is similar to that of a new feature they want to launch. The impact of such a mistake will be worse if the retired feature conflicts with other parts of the software.
Someone could mistake an experiment for a feature release and turn it on for all users. The results of such an experiment will be affected, and the team might have to discard it or start all over again.
These problems are more likely to occur when teams don't have good feature flag management practices. Nevertheless, if feature flags are a part of your development process, you wouldn't want anything to go wrong because you named a feature flag poorly.
Conclusion
The conventions mentioned here are only guides to help you name your feature flags properly. You can tweak them as much as you need, but make sure that your feature flag names are clear enough so that those using them will understand what they do and the implications of toggling them.
And if you’re not using a dedicated feature management platform yet, you should try out ConfigCat. ConfigCat has a free-forever plan that offers a lot of features for small feature flagging use cases.
You can also check out ConfigCat on Github, Facebook, Twitter, and LinkedIn.