Enterprise Java

Swagger UI on MicroProfile OpenAPI

MicroProfile OpenApi gives us a standardized way to describe our JAX-RS API’s using OpenApi 3. If you have used swagger-jaxrs and swagger-annotations before, this will feel very familiar to you as OpenApi is built on the Swagger base.

On Nov. 5, 2015, SmartBear in conjunction with 3Scale, Apigee, Capital One, Google, IBM, Intuit, Microsoft, PayPal, and Restlet announced the formation of the Open API Initiative, an open source project under the Linux Foundation. As part of the formation of the OAI, SmartBear donated the Swagger specification to the Linux Foundation, meaning that the OpenAPI Specification is semantically identical to the specification formerly known as the Swagger 2.0 specificationwww.openapis.org/faq

Quick overview


Firstly, in your class that extends javax.ws.rs.core.Application, add the header information about your API:

    @OpenAPIDefinition(info = @Info(
            title = "Example application", 
            version = "1.0.0", 
            contact = @Contact(
                    name = "Phillip Kruger", 
                    email = "phillip.kruger@phillip-kruger.com",
                    url = "http://www.phillip-kruger.com")
            servers = {
                @Server(url = "/example",description = "localhost")
    public class ApplicationConfig extends Application {


(see full example here)


Then in your service(s), add the annotations describing your service:

  • @Tag
  • @Operation
  • @APIResponse
  • etc.


    @Tag(name = "Config Retrieval service", description = "Get the value for a certain config")
    public class ConfigRetrievalService {

        private Config config;

        @GET @Path("/{key}")
        @Operation(description = "Get the value for this key")
            @APIResponse(responseCode = "200", description = "Successful, returning the value")
        public Response getConfigValue(@PathParam("key") String key) {
            String value = config.getValue(key, String.class);
            log.log(Level.INFO, "{0} = {1}", new Object[]{key, value});

            return Response.ok(value).build();


(see the full example here, and another (fuller) example here)

Getting the openapi yaml

Now if you run your application, you can go to /openapi to get the yaml:

openapi: 3.0.0
      title: Example application
        name: Phillip Kruger
        url: http://www.phillip-kruger.com
        email: phillip.kruger@phillip-kruger.com
      version: 1.0.0
    - url: /example
      description: localhost
    - name: Simulate some exeption
      description: Create some exception
    - name: Config Retrieval service
      description: Get the value for a certain config
          - Config Retrieval service
          description: Get the value for this key
          operationId: getConfigValue
          - name: key
            in: path
            required: true
            style: simple
              type: string
              description: Successful, returning the value
          - Simulate some exeption
          description: Throw an exeption
          operationId: doSomething
              description: You made a mistake
    components: {}

Adding Swagger UI

Above is a quick overview of MicroProfile OpenAPI. Read more about it here:

The latest Swagger UI works on OpenAPI, and you can manually add it to your project (see this great post by Hayri Cicek‏) , or you can use this useful library that will add it automatically:

In your pom.xml:


This will pull in Swagger UI via webjars and generate the index.html from a template that you can configure using MicroProfile Config API.

Just adding the above will already give you the default UI, example:


Swagger UI

Personalize your UI

Using the Config API you can Personalize the UI. Here are the config keys you can use:

  • openapi-ui.copyrightBy – Adds a name to the copyright in the footer. Defaults to none.
  • openapi-ui.copyrightYear – Adds the copyright year. Defaults to current year.
  • openapi-ui.title – Adds the title in the window. Defaults to “MicroProfile – Open API”.
  • openapi-ui.serverInfo – Adds info on the server. Defaults to the system server info.
  • openapi-ui.contextRoot – Adds the context root. Defaults to the current value.
  • openapi-ui.swaggerUiTheme – Use a theme from swagger-ui-themes. Defaults to “flattop”.
  • openapi-ui.swaggerHeaderVisibility – Show/hide the swagger logo header. Defaults to “visible”.
  • openapi-ui.exploreFormVisibility – Show/hide the explore form. Defaults to “hidden”.
  • openapi-ui.serverVisibility – Show/hide the server selection. Defaults to “hidden”.
  • openapi-ui.createdWithVisibility – Show/hide the created with footer. Defaults to “visible”.

Example: Adding this to META-INF/microprofile.properties

openapi-ui.copyrightBy=Phillip Kruger
    openapi-ui.title=My awesome services

will change the UI:

Swagger UI


The default UI uses the flattop theme from swagger-ui-themes, but you can also change that:


Swagger UI


Lastly, you can change the logo to your company logo by including a file named openapi.png in /src/main/resources/:

Swagger UI


For application servers that do not have MicroProfile, see Apiee

Published on Java Code Geeks with permission by Phillip Krüger, partner at our JCG program. See the original article here: Swagger UI on MicroProfile OpenAPI

Opinions expressed by Java Code Geeks contributors are their own.

Phillip Kruger

Phillip is a software developer and a systems architect who knacks for solving problems. He has a passion for clean code and evolutionary architecture. He blogs about all technical things.
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Back to top button