OpenAPI Specification

"The OpenAPI Specification, originally known as the Swagger Specification, is a specification for machine-readable interface files for describing, producing, consuming, and visualizing RESTful web services." - Wikipedia. Often OpenAPI specification acts as documentation for developers. It helps UI and Backend developers to work side by side.

Release date: January 2021 | Spring Boot: 2.4.x | Revision: 1

Action: OpenAPI

Enable OpenAPI

Springfox provide good support to auto generate OpenAPI specification. They have spring boot starter io.springfox:springfox-boot-starter library for spring boot project. To enable OpenAPI do the following.

Include version information at gradle.properties.
gradle.properties
```
projectName=Brain Station 23 Bank
#
openApiVersion=3.0.0
```

Include springfox starter at build.gradle.

build.gradle

dependencies {
    compileOnly "io.springfox:springfox-boot-starter:${openApiVersion}"
}

Enable spring boot build properties through gradle build configuration to build.gradle. After enabling spring boot build properties, spring boot will generate build-info.properties inside the .jar which is accessible during runtime. We will use build properties to dynamically generates OpenAPI information (e.g. project name, version or any custom information).
build.gradle
```
springBoot {
    buildInfo {
        properties {
            name = projectName
        }
    }
}
```

Add java configuration to override default configurations.

OpenApiConfiguration.java

@Configuration
@ConditionalOnClass(OpenApiAutoConfiguration.class)
public class OpenApiConfiguration {

  private final BuildProperties buildProperties;

  public OpenApiConfiguration(BuildProperties buildProperties) {
    this.buildProperties = buildProperties;
  }

  @Bean
  public Docket api() {
    return new Docket(DocumentationType.OAS_30)
        .groupName(buildProperties.getName() + " " + buildProperties.getVersion())
        .select()
        .apis(RequestHandlerSelectors.withClassAnnotation(RestController.class))
        .paths(PathSelectors.any())
        .build()
        .apiInfo(
            new ApiInfoBuilder()
                .title(buildProperties.getName() + " API")
                .description(buildProperties.getName() + " REST API")
                .version(buildProperties.getVersion())
                .license("© Brain Station 23 Ltd.")
                .licenseUrl("https://brainstation-23.com")
                .contact(
                    new Contact(
                        "Md. Rezaul Hasan", "https://brainstation-23.com/", "reza@bs-23.net"))
                .build());
  }
}

Now OpenAPI specification will be accessible at http://localhost:8081/swagger-ui/index.html It will look like the bellow.

Learn More

Official Springfox Documentation

Project Code

Github - OpenAPI Specification

Next Step

Design Rest API