Retrofit Spring Boot Auto Configuration

Retrofit 2 is just a simple abstraction for http request. The backend of its to perform http request is mainly depends on okhttp3. We also support async http request out of the box.

Dependency

<dependency>
    <groupId>in.abilng.spring</groupId>
    <artifactId>retrofit-spring-boot-starter</artifactId>
    <version>${latest_version}</version>
</dependency>

or Gradle:

implementation("in.abilng.spring:retrofit-spring-boot-starter:${latest_version}")

Note: To enable circuit breaker & retry metrics, you need add following along with retrofit-spring-boot-starter

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-spring-boot3</artifactId>
            <version>2.2.0</version>
        </dependency>
        <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-spring-boot3</artifactId>
            <version>2.2.0</version>
        </dependency>
        <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-micrometer</artifactId>
            <version>2.2.0</version>
        </dependency>
        <dependency>
            <groupId>io.micrometer</groupId>
            <artifactId>micrometer-registry-prometheus</artifactId> <!-- or any other implementations  of micrometer -->
        </dependency>
    </dependencies>

or Gradle:

implmenation("org.springframework.boot:spring-boot-starter-actuator")
implmenation("io.github.resilience4j:resilience4j-spring-boot3:2.2.0")
implmenation("io.github.resilience4j:resilience4j-micrometer:2.2.0")
implmenation("io.micrometer:micrometer-registry-prometheus") // or other implementations of micrometer

Detailed Usage in Springboot Application

All the customize retrofit interface should be annotated with @Retrofit annotation, that would make these interface could be registed our own bean creation process. e.g.:

@Retrofit("open-library")
public interface IOpenLibClient {
    
    @GET("/search.json")
    Call<SearchResult> search(@Query("title") String title,
                              @Query("limit") Integer limit);
    //...

}

@Retrofit have three properties, the name or value stand for the identity of the retrofit configuration that your would like to use (It would be clarified in configuration file part). qualifier attribute means the spring's bean name. If no attributes provided, we set ${name}RetrofitClient as the bean name.

In you application.{propeties|yaml} set the configuration needed to send http request.

For Example, following properties can be used to configure open-library

retrofit.services.open-library.base-url=https://openlibrary.org/ #The system prefix url
retrofit.services.open-library.connection.read-timeout=10000
retrofit.services.open-library.connection.write-timeout=10000
retrofit.services.open-library.connection.connect-timeout=10000

You can now @Autowired the retrofit interface to send real http request. e.g.:

@Autowired
private final IOpenLibClient endpoint;

Features

• Retry
• Circuit Breaker
• Micrometer Metrics
• Auth Header Propagation (when propagate-auth-header=true)