Chapter 92. Openapi Java

You can enable the OpenApi api from the rest-dsl by configuring the apiContextPath dsl as shown below:

public class UserRouteBuilder extends RouteBuilder {
    @Override
    public void configure() throws Exception {
        // configure we want to use servlet as the component for the rest DSL
        // and we enable json binding mode
        restConfiguration().component("netty-http").bindingMode(RestBindingMode.json)
            // and output using pretty print
            .dataFormatProperty("prettyPrint", "true")
            // setup context path and port number that netty will use
            .contextPath("/").port(8080)
            // add OpenApi api-doc out of the box
            .apiContextPath("/api-doc")
                .apiProperty("api.title", "User API").apiProperty("api.version", "1.2.3")
                // and enable CORS
                .apiProperty("cors", "true");

        // this user REST service is json only
        rest("/user").description("User rest service")
            .consumes("application/json").produces("application/json")
            .get("/{id}").description("Find user by id").outType(User.class)
                .param().name("id").type(path).description("The id of the user to get").dataType("int").endParam()
                .to("bean:userService?method=getUser(${header.id})")
            .put().description("Updates or create a user").type(User.class)
                .param().name("body").type(body).description("The user to update or create").endParam()
                .to("bean:userService?method=updateUser")
            .get("/findAll").description("Find all users").outType(User[].class)
                .to("bean:userService?method=listUsers");
    }
}

The OpenApi module can be configured using the following options. To configure using a servlet you use the init-param as shown above. When configuring directly in the rest-dsl, you use the appropriate method, such as enableCORS, host,contextPath, dsl. The options with api.xxx is configured using apiProperty dsl.

The Rest DSL now supports declaring OpenApi securityDefinitions in the generated API document. For example as shown below:

rest("/user").tag("dude").description("User rest service")
    // setup security definitions
    .securityDefinitions()
        .oauth2("petstore_auth").authorizationUrl("http://petstore.swagger.io/oauth/dialog").end()
        .apiKey("api_key").withHeader("myHeader").end()
    .end()
    .consumes("application/json").produces("application/json")

Here we have setup two security definitions

Then you need to specify on the rest operations which security to use by referring to their key (petstore_auth or api_key).

.get("/{id}/{date}").description("Find user by id and date").outType(User.class)
    .security("api_key")

...

.put().description("Updates or create a user").type(User.class)
    .security("petstore_auth", "write:pets,read:pets")

Here the get operation is using the Api Key security and the put operation is using OAuth security with permitted scopes of read and write pets.

The camel-openapi-java module supports both JSon and Yaml out of the box. You can specify in the request url what you want returned by using /openapi.json or /openapi.yaml for either one. If none is specified then the HTTP Accept header is used to detect if json or yaml can be accepted. If either both is accepted or none was set as accepted then json is returned as the default format.

The OpenApi specification allows you to specify the host, port & path that is serving the API. In OpenApi V2 this is done via the host field and in OpenAPI V3 it is part of the servers field.

By default, the value for these fields is determined by X-Forwarded headers, X-Forwarded-Host & X-Forwarded-Proto.

This can be overridden by disabling the lookup of X-Forwarded headers and by specifying your own host, port & scheme on the REST configuration.

restConfiguration().component("netty-http")
    .useXForwardHeaders(false)
    .apiProperty("schemes", "https");
    .host("localhost")
    .port(8080);

In the Apache Camel distribution we ship the camel-example-openapi-cdi and camel-example-spring-boot-rest-openapi-simple which demonstrates using this OpenApi component.

When using openapi-java with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-openapi-java-starter</artifactId>
</dependency>

The component supports 1 options, which are listed below.