How to configure Togglz 2.9.6

Aloha,

as Java developer there is sometimes the need for a feature flags when you are following the trunk based development strategy. The project Togglz is a great example to make feature flags viable and easy to use. I found it configuring though sometimes really hard. The documentation is out of date and there are too many ways to configure the plugin for my liking. Let's have a look at the basic configuration for a simple SpringBoot application. For that i used the SpringBoot generator which can be found here. There is also great websites like JHipster which help you configuring SpringBoot applications with web dependencies.

I used gradle for this example but you could also use maven:

// build.gradle
plugins {
    id 'org.springframework.boot' version '2.4.3'
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'java'
}

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '15'

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter'
    compileOnly 'org.projectlombok:lombok'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation("org.assertj:assertj-core:3.19.0")

//  Togglz
    implementation("org.togglz:togglz-spring-boot-starter:2.9.6")
}

test {
    useJUnitPlatform()
}

What you definitly need is an enum in which you can define the feature flags:

// TogglzFeatures.java
import org.togglz.core.Feature;
import org.togglz.core.annotation.Label;

public enum TogglzFeatures implements Feature {
    @Label("Toggle Description")
    MY_TOGGLE;
}

These flags are set to false by default and to enable them you need to configure togglz in your application.yaml or application.properties.

//application.properties
togglz.enabled=true
togglz.features.MY_TOGGLE.enabled=true

This configuration should all you would need but in my case this was not enough. I currently don't know the reason but the something prevented the Togglz libary to supply a bean of UserProvider.class which caused the application to fail on startup. The error message was intiutive as always for java errors: Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.togglz.core.user.UserProvider' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}

The solution to this problem was to create a configuration class for Togglz and supply the NoOpsUserProvider bean myself.

@Configuration
public class TogglzConfiguration {
  @Bean
  public FeatureProvider featureProvider() {
    return new EnumBasedFeatureProvider(TogglzFeatures.class);
  }

  @Bean
  public UserProvider getUserProvider() {
    return new NoOpUserProvider();
  }
}

If you had this problem and solved it differently, please let me know in the comments.