Swagger2Feature

The CXF Swagger2Feature allows you to generate Swagger 2.0 documents from JAX-RS service endpoints with a simple configuration.

For generating Swagger 1.2 documents, you can use SwaggerFeature instead of Swagger2Feature (for CXF versions <= 3.1.x).

These features can be configured programatically in Java or using Spring or Blueprint beans.

Setup

<dependency>
    <groupId>org.apache.cxf</groupId>
    <artifactId>cxf-rt-rs-service-description-swagger</artifactId>
    <version>3.1.11</version>
</dependency>

Note that a cxf-rt-rs-service-description needs to be used if older CXF 3.1.x versions are used.

Properties

The following optional parameters can be configured in Swagger2Feature

Note some properties listed below are not available or used differently in SwaggerFeature, as the corresponding properties are used differently in Swagger 2.0 and Swagger 1.2. Please refer to the corresponding Swagger documentation for more information.)

Note: those descriptions marked with + correspond to the properties defined in Swagger's BeanConfig, and those marked with ++ correspond to the properties defined in Swagger's ReaderConfig.

Configuring from Code

import org.apache.cxf.frontend.ServerFactoryBean;
import org.apache.cxf.jaxrs.swagger.Swagger2Feature;
...

Swagger2Feature feature = new Swagger2Feature();

// customize some of the properties
feature.setBasePath("/api");
    	
// add this feature to the endpoint (e.g., to ServerFactoryBean's features) 
ServerFactoryBean sfb = new ServerFactoryBean();
sfb.getFeatures().add(feature);

Configuring in Spring

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:cxf="http://cxf.apache.org/core"
       xmlns:jaxrs="http://cxf.apache.org/jaxrs"
       xsi:schemaLocation="http://cxf.apache.org/core http://cxf.apache.org/schemas/core.xsd
                           http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd
                           http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    ... 
    <!-- JAXRS providers -->
    <bean id="jsonProvider" class="com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider" />

    <!-- Application resources -->
    <bean id="sampleResource" class="demo.jaxrs.swagger.server.Sample" />

    <!-- CXF Swagger2Feature -->  
    <bean id="swagger2Feature" class="org.apache.cxf.jaxrs.swagger.Swagger2Feature">
        <!-- customize some of the properties -->
        <property name="basePath" value="/app/swaggerSample"/>
    </bean>

    ...
    <jaxrs:server id="sampleServer" address="/swaggerSample">
        <jaxrs:serviceBeans>
            <ref bean="sampleResource" />
        </jaxrs:serviceBeans>
        <jaxrs:providers>
            <ref bean="jsonProvider" />
        </jaxrs:providers>
        <jaxrs:features>
            <ref bean="swagger2Feature" />
        </jaxrs:features>
    </jaxrs:server>
</beans>

Configuring in Blueprint

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:cxf="http://cxf.apache.org/blueprint/core"
       xmlns:jaxrs="http://cxf.apache.org/blueprint/jaxrs"
       xsi:schemaLocation="http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
                           http://cxf.apache.org/blueprint/core http://cxf.apache.org/schemas/blueprint/core.xsd
                           http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/blueprint/jaxrs.xsd"> 
    ...
    <!-- JAXRS providers -->
    <bean id="jsonProvider" class="com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider" />
 
    <!-- Application resources -->
    <bean id="sampleResource" class="demo.jaxrs.swagger.server.Sample" />


    <!-- CXF Swagger2Feature -->  
    <bean id="swagger2Feature" class="org.apache.cxf.jaxrs.swagger.Swagger2Feature">
        <!-- customize some of the properties -->
        <property name="basePath" value="/cxf/swaggerSample"/>
    </bean>
 
    ...
    <jaxrs:server id="sampleServer" address="/swaggerSample">
        <jaxrs:serviceBeans>
            <ref component-id="sampleResource" />
        </jaxrs:serviceBeans>
        <jaxrs:providers>
            <ref component-id="jsonProvider" />
        </jaxrs:providers>
        <jaxrs:features>
            <ref component-id="swagger2Feature" />
        </jaxrs:features>
    </jaxrs:server>
</blueprint>
 

Configuring in CXFNonSpringJaxrsServlet

<web-app>
    <context-param>
        <param-name>contextParam</param-name>
        <param-value>contextParamValue</param-value>
    </context-param>
    <servlet>
        <servlet-name>CXFServlet</servlet-name>
        <display-name>CXF Servlet</display-name>
        <servlet-class>
              org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet
        </servlet-class>
        <init-param>
            <param-name>jaxrs.serviceClasses</param-name>
            <param-value>
                           org.apache.cxf.systest.jaxrs.BookStore
            </param-value>
        </init-param>
        <init-param>
            <param-name>jaxrs.features</param-name>
            <param-value>
                        org.apache.cxf.jaxrs.swagger.Swagger2Feature
                        (basePath=/somepath)
            </param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>CXFServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
    
</web-app>

New: Configuring from Properties file

Starting from CXF 3.1.13 and 3.2.0 it is possible to configure Swagger2Feature with a Properties file.

For example, while a samples/jax_rs/spring_boot demo configures the feature from the code, a  samples/jax_rs/spring_boot_scan demo has it configured from the properties file.

Default location for a properties file is "/swagger.properties". Swagger2Feature will pick it up if it is available, and the location can be overridden with a new Swagger2Feature 'swaggerPropertiesLocation' property. 

Note that the properties, if available, do not override the properties which may have been set as suggested above from the code or Spring/Blueprint contexts or web.xml. Instead they complement and serve as the default configuration properties: for example, if some properties have been set from the code then the values for the same properties found in the properties file will not be used.

Enabling in Spring Boot

See samples/jax_rs/spring_boot and on how to create Swagger2Feature in a @Bean method or/and samples/jax_rs/spring_boot_scan on how to auto-enable it.

Accessing Swagger Documents

When Swagger is enabled by Swagger feature, the Swagger documents will be available at the location URL constructed of the service endpoint location followed by /swagger.json or /swagger.yaml.

For example, lets assume a JAX-RS endpoint is published at 'http://host:port/context/services/' where 'context' is a web application context,  "/services" is a servlet URL. In this case its Swagger documents are available at 'http://host:port/context/services/swagger.json' and 'http://host:port/context/services/swagger.yaml'.

Starting from CXF 3.1.7 the CXF Services page will link to Swagger documents if Swagger2Feature is active. 

In the above example, go to 'http://host:port/context/services/services' and follow a Swagger link which will return a Swagger JSON document.

If CORS support is needed to access the definition from a Swagger UI on another host, the CrossOriginResourceSharingFilter from cxf-rt-rs-security-cors can be added.

Enabling Swagger UI

First one needs to add the following

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>swagger-ui</artifactId>
    <version>2.2.10-1</version>
</dependency>

The newest version 3.x of swagger-ui can also be used.

Enabling Swagger UI in OSGi container (Karaf)

Since org.webjars/swagger-ui is just a package with resources, it won't be referenced in OSGi manifest as the required imports. Therefore, to make use of Swagger UI in the OSGi deployments, the org.webjars/swagger-ui should be installed manually, for example:

karaf@root()> install mvn:org.webjars/swagger-ui/3.23.8

The dedicated Activator will take care of discovering the presence of the org.webjars/swagger-ui bundle and configuring Swagger2Feature.

Automatic UI Activation

This feature is available starting from CXF 3.1.7: Adding a Swagger UI Maven dependency is all what is needed to start accessing Swagger documents with the help of Swagger UI.

For example, lets assume a JAX-RS endpoint is published at 'http://host:port/context/services/'.

Open the browser and go to 'http://host:port/context/services/api-docs/?url=/swagger.json' which will return a Swagger UI page.

CXF Services page will also link to Swagger UI. Go to 'http://host:port/context/services/services' and follow a Swagger link which will return a Swagger UI page.

See samples/jax_rs/description_swagger2, samples/jax_rs/description_swagger2_web, samples/jax_rs/spring_boot and samples/jax_rs/spring_boot_scan 

Note that CXF OSGI endpoints can only depend on this feature starting from CXF 3.1.8.

Unpacking Swagger UI resources

Up until CXF 3.1.7 unpacking Swagger UI resources into the local folder was the only option. It is demoed in samples/jax_rs/description_swagger2_spring and samples/jax_rs/description_swagger2_osgi.

In CXF 3.1.8: set Swagger2Feature 'supportSwaggerUi' property to 'false' to disable the automatic UI activation described in the previous section

Configuring Swagger UI (3.2.7+)

The Swagger2Feature  has a way to pre-configure certain  Swagger UI parameters (https://github.com/swagger-api/swagger-ui/blob/master/docs/usage/configuration.md) through SwaggerUiConfig. The way it is implemented is by passing those parameters as a query string so the Swagger UI could adjust itself.

new SwaggerUiConfig()
    .url("/swagger.json")
    ...
    .queryConfigEnabled(false)

Reverse Proxy

Set a CXFServlet init parameter 'use-x-forwarded-headers' to 'true' if you access Swagger JSON and/or UI via the reverse proxy. If you use CXF SpringBoot starters then this property is prefixed with a "cxf.servlet.init.", "cxf.servlet.init.use-x-forwarded-headers".

You may also need to set Swagger2Feature 'usePathBasedConfig' property to 'true' to prevent Swagger from caching the 'basePath' value.

Converting to OpenAPI JSON

OpenAPI specification has been released and the CXF team has started working on the new feature which will produce OpenAPI JSON with the help of the new core and jaxrs libraries being currently developed by the Swagger community.

In meantime, while the new feature development is taking place, one can experiment with converting the Swagger JSON produced by CXF Swagger2Feature into Open API JSON.

All what is needed is registering SwaggerToOpenApiConversionFilter with the JAX-RS endpoint and requesting an "openapi.json" as opposed to "swagger.json". The filter will let Swagger2Feature generate JSON as usual and then convert the response to OpenAPI JSON if requested by the user or leave it intact otherwise. By issuing either "swagger.json" or "openapi.json" queries one can easily see the difference  between the two formats.

The cxf-rt-rs-json-basic dependency must be on the classpath as well.

Note, OpenAPI JSON (see also OpenApiFeature) allows referring to its new "components/requestBodies" section from the multiple "requestBody" elements (which can be found under the specific path/http verb sub-sections). By default the filter will instead inline the the "requestBody" definitions inside of "requestBody" elements, but one can experiment with referring to the "components/requestBodies" by configuring the filter to create the request bodies.   

The conversion filter is available starting from CXF 3.1.15 and 3.2.2

Samples

CXF's distribution contains the following samples.

• samples/jax_rs/description_swagger: Swagger 1.2 sample using SwaggerFeature programatically
• samples/jax_rs/description_swagger2: Swagger 2.0 standalone sample using Swagger2Feature programatically
• samples/jax_rs/description_swagger2_spring: Swagger 2.0 standalone sample using Swagger2Feature using Spring
• samples/jax_rs/description_swagger2_web: Swagger 2.0 web application sample using Swagger2Feature using Spring
• samples/jax_rs/description_swagger2_osgi: Swagger 2.0 OSGi application sample using Swagger2Feature using Blueprint