Spring Boot Resilience4J: Unresolved dependency - spring

Question

I am trying to implement Resilience4j in a sample application and I was following the demo application from the official documentation. But adding the below dependencies gives me a gradle error:
Unresolved dependency: org.springframework.cloud spring-cloud-starter-circuitbreaker-reactor-resilience4j
Here is my build.gradle
plugins {
id 'org.springframework.boot' version '2.7.2'
id 'io.spring.dependency-management' version '1.0.12.RELEASE'
id 'java'
}
group = 'com.thomsoncodes'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'
repositories {
mavenCentral()
}
ext {
set('springCloudVersion', "2021.0.3")
}
ext{
resilience4jVersion = '1.7.1'
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'org.springframework.boot:spring-boot-starter-webflux'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
testImplementation 'io.projectreactor:reactor-test'
compile('org.springframework.boot:spring-boot-starter-aop')
compile("io.github.resilience4j:resilience4j-spring-boot2:${resilience4jVersion}")
compile("io.github.resilience4j:resilience4j-all:${resilience4jVersion}") // Optional, only required when you want to use the Decorators class
compile("io.github.resilience4j:resilience4j-reactor:${resilience4jVersion}")
}
dependencyManagement {
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
}
}
tasks.named('test') {
useJUnitPlatform()
}

Answer 1

try to change the version to 1.7.0. I have had the similar error some days ago. For some reason there seems to be a problem with transitive dependencies related to the spring-boot2 artifact. The artifact itself is in the version 1.7.1 but all transitive dependencies are 1.7.0.
After the change all versions were then 1.7.0 and it worked.

Answer 2

The issue is caused by using spring-cloud in your project, too. spring-cloud's bom is adding spring-cloud-circuitbreaker-dependencies-x.y.z.pom into your classpath defining its own dependency for resilience4j. At the time of my investigation spring-cloud version 2021.0.5 defines still resilience4j.version 1.7.0.
The issue was already reported in an older post here: https://github.com/resilience4j/resilience4j/issues/848
If you want to use a more recent version of resilience4j you can overwrite the dependency imports in build.gradle on your own or exclude the imports originating from spring-cloud.
For me utilizing Maven instead of Gradle adding another dependency for resilience4j-bom solved the issue.
<properties>
<resilience4j.version>2.0.2</resilience4j.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>io.github.resilience4j</groupId>
<artifactId>resilience4j-bom</artifactId>
<version>${resilience4j.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>