Fast Feature-Flags Provider

An open feature provider to operate with MongoDB

---

Pre-requisites

• MongoDB running (see for an example in examples/docker-compose.yml) )
• import the dependency in your pom.xmlfrom maven central.

    <dependency>
        <groupId>io.github.jacopocarlini</groupId>
        <artifactId>fast-feature-flags-provider</artifactId>
        <version>X.X.X</version>
    </dependency>

Alternative Articat Repository

If you want to use Github package registry, add the following snippet to your pom.xml. You need a PAT token with read packages scope.

<repositories>
    <repository>
        <id>github</id>
        <url>https://public:${env.YOUR_GITHUB_TOKEN_READ_PACKAGES}@maven.pkg.github.com/jacopocarlini/fast-feature-flags-provider</url>
    </repository>
</repositories>

How To Use

There are two versions of this provider: the MongoDBFeatureFlagProvider, which implements only the basic openFeature methods to evaluate flags, and the MongoDBFeatureFlagProviderExtended, which includes additional methods for retrieving, creating, deleting, and updating flags.

In your Java class:

  import it.jacopocarlini.fffp.providers.MongoDBFeatureFlagProvider;
  ...
  
  public static void main(String[] args) {
    OpenFeatureAPI openFeatureAPI = OpenFeatureAPI.getInstance();
    
    // set the connection string
    MongoDBFeatureFlagProviderExtended provider =
        new MongoDBFeatureFlagProviderExtended(
            "mongodb://user:adminpassword@localhost:27017/openfeature?authSource=admin");
    openFeatureAPI.setProvider(provider);
    
    // create a flag
    Flag flag =
        Flag.builder()
            .flagKey("font")
            .enabled(true)
            .variants(
                new HashMap<>() {
                  {
                    put("small", "12");
                    put("medium", "14");
                    put("big", "18");
                  }
                })
            .defaultVariant("medium")
            .build();
    provider.crateFlag(flag);
    
    // evaluate
    Client client = openFeatureAPI.getClient();
    var value =
        client.getStringValue("font", "10");
    
    System.out.println(value);
  }
}

If the flag is not enabled the value will be the defaultValue passed in client.getStringValue("font", "10").

Parameter	Required	Description
flagKey	yes	the flag key
enabled	yes	if the flag is enabled
variants	yes	a map of variants
defaultVariant	yes	the default variant
timeWindow	no	the time window
target	no	the target
rollout	no	the rollout percentage

Set a Time Window

You can set a time window to evaluate the flag. If the current time is outside the time window the flag will always be disabled.

Flag.builder()
    ...
    .timeWindowStart(ZonedDateTime.of(2025, 1, 1, 0, 0))
    .timeWindowEnd(ZonedDateTime.of(2026, 1, 2, 0, 0))
    .build();

Set a Target

You can force a variant specifying a regex to match the targeting key.

Flag.builder()
    ...
    .defaultVariant("medium")
    .target(
        Collections.singletonList(
            Target.builder()
                .filter(".*@email.it")
                .variant("big")
                .build()
        )
    )
    .build();
    
 client.getStringValue("font", "0", new MutableContext().setTargetingKey("nickname@email.it"));
))

Set a Rollout Percentage

You can set a rollout percentage foreach variant.

Flag.builder()
  ...
  .rolloutPercentage(
            new HashMap<>() {
              {
                put("small", 50);
                put("medium", 50);
                put("big", 0);
              }
            })
    .build();

NOTE: When a target key is provided in the context, the random assigned variant is persisted and used on subsequent evaluations, overriding the rollout percentage. When the rollout percentage is modified or deleted, the assigned variant is also removed.