JarCastingdropwizard-resilience4j-bundle 
Lightweight integration of Resilience4J into Dropwizard configuration and metrics. Does not provide any other services - actually using all the Resilience4j stuff is up to you. The R4J documentation is pretty good.
Currently, this only supports Circuit Breakers and Retries, but supporting more R4j features is welcome.
User Guide
In your POM...
<dependency>
<groupId>com.expediagroup.dropwizard</groupId>
<artifactId>dropwizard-resilience4j-bundle</artifactId>
<version>3.0.0</version> <!-- use latest -->
</dependency>
In your config.yaml...
resilience4j:
circuitBreakers:
- name: myFancyCircuitBreaker
waitDurationInOpenState: 30s
failureRateThreshold: 10
## Add as many as you want
## All parameters are optional except `name`, defaults are documented in CircuitBreakerConfiguration.java
##- name: anotherCircuitBreaker
retryConfigurations:
- name: exponentialRandomizedBackoffRetry
maxAttempts: 4
intervalFunction:
type: exponentialRandomBackoff
initialInterval: 10ms
multiplier: 2.5
randomizationFactor: 0.5
## Add as many as you want
## most parameters are optional, but `intervalFunction` is required. Several are available, see `IntervalFunctionFactory` for full list,
## but currently: constant, randomized, exponentialBackoff, exponentialRandomBackoff
Add to your application's Config class:
@NotNull
private Resilience4jConfiguration resilience4j;
Configured R4J objects are automatically wired into Dropwizard Metrics, and also into HK2 using the name from the YAML. You can also retrieve them from the configuration class...
val breaker = myAppConfig.getResilience4j().getCircuitBreakerRegistry().circuitBreaker("myFancyCircuitBreaker");
val retry = myAppConfig.getResilience4j().getRetryRegistry().retry("myFancyRetry");
If you want to configure the objects in code before they are created, you can pass a handler into the bundle when it's constructed.
@Override
public void initialize(Bootstrap<RatesEngineConfiguration> bootstrap) {
bootstrap.addBundle(new Resilience4jBundle<>(TestConfiguration::getResilience4j,
(breakerName, breakerBuilder) -> {
//breakerName is what was configured in YAML
//breakerBuilder can be modified as desired
breakerBuilder.ignoreExceptions(IOException.class);
},
(retryName, retryBuilder) -> {
//retryName is what was configured in YAML
//retryBuilder can be modified as desired
retryBuilder.retryOnResult(myRetryPredicate);
}));
}
