Circuit breaker with Resilience4j in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to annotate a method with a circuit breaker using Resilience4j.

Spring Boot

@CircuitBreaker(name = "[1]")
public String callExternalService() {
    // method implementation
}

Drag options to blanks, or click blank then click option'

AexternalService

BserviceCall

CcircuitBreaker

DbackendService

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic name that does not match configuration

Leaving the name blank

Using an invalid identifier

The circuit breaker name should match the configured backend service name, here 'backendService'.

2fill in blank

medium

Complete the code to configure the circuit breaker failure rate threshold in application.yml.

Spring Boot

resilience4j.circuitbreaker.instances.backendService.failureRateThreshold: [1]

Drag options to blanks, or click blank then click option'

A50

B100

C25

D75

Attempts:

3 left

💡 Hint

Common Mistakes

Setting failure rate threshold too high or too low

Using invalid numeric values

Forgetting to specify the correct instance name

The failure rate threshold is commonly set to 50%, meaning the circuit breaker opens if failures exceed 50%.

3fill in blank

hard

Fix the error in the annotation to enable fallback method on circuit breaker failure.

Spring Boot

@CircuitBreaker(name = "backendService", fallbackMethod = "[1]")
public String callExternalService() {
    // method implementation
}

Drag options to blanks, or click blank then click option'

AhandleFallback

BfallbackHandler

CfallbackMethod

Dfallback

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic or incorrect fallback method name

Not defining the fallback method at all

Mismatch in method parameters

The fallback method name must match the actual method defined to handle failures, here 'handleFallback'.

4fill in blank

hard

Fill both blanks to configure the wait duration and sliding window size for the circuit breaker.

Spring Boot

resilience4j.circuitbreaker.instances.backendService.waitDurationInOpenState: [1]
resilience4j.circuitbreaker.instances.backendService.slidingWindowSize: [2]

Drag options to blanks, or click blank then click option'

A30s

B60s

C100

D50

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing units between time and count

Setting too small or too large values

Using invalid formats like missing 's' for seconds

The wait duration is set to 60 seconds and sliding window size to 50 calls for balanced circuit breaker behavior.

5fill in blank

hard

Fill all three blanks to complete the method signature for a fallback method with exception parameter.

Spring Boot

public String [1](Throwable [2]) {
    return "Fallback response due to " + [3].getMessage();
}

Drag options to blanks, or click blank then click option'

AhandleFallback

Bex

Cexception

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between fallback method name and annotation

Using different parameter names inconsistently

Not including Throwable parameter

The fallback method is named 'handleFallback' and uses 'ex' as the Throwable parameter to get the error message.