OpenApiFeature (Microprofile)

Created by Andriy Redko, last modified on Sep 14, 2020

Introduction

The CXF OpenApiFeature allows you to generate OpenAPI v3.0 documents from JAX-RS service endpoints with a simple configuration. This feature can be configured programmatically in Java or using Spring or Blueprint beans and is an alternative to Swagger's OpenApiFeature.

Setup

<dependency>
    <groupId>org.apache.cxf</groupId>
    <artifactId>cxf-rt-rs-service-description-microprofile-openapi</artifactId>
    <version>3.4.0</version>
</dependency>

The cxf-rt-rs-service-description-microprofile-openapi is only available in 3.4.0. For older releases, please consider Swagger's OpenApiFeature instead.

Properties

The following optional parameters can be configured in OpenApiFeature (please note there are some differences comparing to Swagger's OpenApiFeature).

configLocation	the OpenAPI configuration location	null	/config/openapi-configuration.yml
scanKnownConfigLocations	scan known OpenAPI configuration location (classpath or filesystem), which are: openapi-configuration.yaml openapi-configuration.json openapi.yaml openapi.json	true	true
propertiesLocation	the properties file location	/swagger.properties	/swagger.properties
swaggerUiMavenGroupAndArtifact	the Maven artifacts to pinpoint SwaggerUI	null	"org.webjars.swagger-ui'
swaggerUiVersion	the version of SwaggerUI	null	"3.13.0"
supportSwaggerUi	turns on/off SwaggerUI support	null (== true)	true
filterClass	a security filter**	null	"com.example.filter.SampleFilter"
resourceClasses	a list of resource classes which must be scanned**	null	["com.example.rest.SampleResource"]
resourcePackages	a list of package names where resources must be scanned**	null	["com.example.rest"]
ignoredRoutes	excludes specific paths when scanning all resources (see scanAllResources)**	null	["/api/test"]
prettyPrint	when generating openapi.json, pretty-print the JSON document**	true	true
runAsFilter	runs the feature as a filter	false	false
scan	Scan all JAX-RS resources automatically	true	true
readAllResources	Read all operations also with no @Operation**	true	true
termsOfServiceUrl	the terms of service URL*	null	null
licenseUrl	the license URL*	null	"http://www.apache.org/licenses/LICENSE-2.0.html"
license	the license*	null	"Apache 2.0 License"
contactUrl	the contact link*	null	null
contactEmail	the contact email*	null	"users@cxf.apache.org"
contactName	the contact name*	null	null
description	the description*	null	"The Sample REST Application with OpenAPI integration"
title	the title*	null	"Sample REST Application"
version	the version*	null	"1.0.0"
swaggerUiConfig	Swagger UI configuration	null	new SwaggerUiConfig().url("/openapi.json")

* - the properties are defined in the OpenAPI class

** - the properties are defined in the SwaggerConfiguration class

Configuring from Code

import org.apache.cxf.jaxrs.microprofile.openapi.OpenApiFeature;

...

final OpenApiFeature feature = new OpenApiFeature();
feature.setContactEmail("cxf@apache.org");
feature.setLicense("Apache 2.0 License");
feature.setLicenseUrl("http://www.apache.org/licenses/LICENSE-2.0.html");

Configuring from 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">
    ...
    
    <bean id="jsonProvider" class="com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider" />

    
    <bean id="sampleResource" class="demo.jaxrs.openapi.server.Sample" />

    
    <bean id="openApiFeature" class="org.apache.cxf.jaxrs.microprofile.openapi.OpenApiFeature">
        
    </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="openApiFeature" />
        </jaxrs:features>
    </jaxrs:server>
</beans>

Configuring from Property files

It is possible to supply the configuration from the property files. The default location for a properties file is "/swagger.properties". OpenApiFeature will pick it up if it is available, and the location can be overridden with a 'propertiesLocation' 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 Swagger UI

Adding a Swagger UI Maven dependency is all what is needed to start accessing Swagger documents with the help of Swagger UI.

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>swagger-ui</artifactId>
    <version>3.13.0</version>
</dependency>

For example, let's 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=/openapi.json' which will return a Swagger UI page.

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

See samples/jax_rs/description_openapi_microprofile_spring as an example.

To deactivate automatic Swagger UI integration please set 'supportSwaggerUi' property to "false".

Configuring Swagger UI

The OpenApiFeature 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.

Samples

CXF's distribution contains the following samples.

samples/jax_rs/description_openapi_microprofile_spring: the OpenAPI v3.0 standalone sample using Spring and OpenApiFeature programmatic configuration

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