Centralized Swagger/OpenAPI UI for all the different microservices on a single swagger URL i.e accessing all the URLs through one - spring-boot

Question

I have around 16 microservices built in Spring Boot that communicate with each other and each microservice is having multiple APIs in it. I have configured OpenAPI for each of the microservices. So it gives me 16 "swagger-ui" URLs.
I wonder how can I centralize all Swagger URLs on one single page; I want only 1 swagger URL to access all the 16 microservices.
I have gone through the following as well but didn't get any solution
Centralize Swagger at one place for All microservices
Please guide me to the best way to achieve it.

Answer 1

I found a working solution on GitHub. It works with Spring Cloud Discovery but can be easily adapted to other discovery solutions. The basic idea is to generate for Swagger the list of URLs pointing to the OpenAPI JSON files.
The result is similar to one in the #shadyx's answer, but the list is generated dynamically
#RestController
public class SwaggerUiConfig {
#Autowired
private DiscoveryClient discoveryClient;
#GetMapping("/swagger-config.json")
public Map<String, Object> swaggerConfig() {
List<SwaggerUrl> urls = new LinkedList<>();
discoveryClient.getServices().forEach(serviceName ->
discoveryClient.getInstances(serviceName).forEach(serviceInstance ->
urls.add(new SwaggerUrl(serviceName, serviceInstance.getUri() + "/v3/api-docs"))
)
);
return Map.of("urls", urls);
}
}
application.yaml
springdoc:
swagger-ui:
configUrl: "/swagger-config.json"
Sample of the generated swagger-config.json
{
"urls": [
{
"url": "http://localhost:8088/v3/api-docs/users",
"name": "users"
},
{
"url": "http://localhost:8088/v3/api-docs/stores",
"name": "stores"
}
]
}

Answer 2

If all you µservices use the same host, you can create a Spring Boot µservice which acts as a openAPI gateway using spring-doc. (If they are not using the same host, you will have to deal with CORS issues)
First, add the following dependencies to your new gateway µservice
<dependency>
<groupId>org.springdoc</groupId>
<artifactId>springdoc-openapi-ui</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
Then, add the below configuration
springdoc:
api-docs:
enabled: true
swagger-ui:
configUrl: ${server.servlet.contextPath}/v3/api-docs/swagger-config
url: ${server.servlet.contextPath}/v3/api-docs
urls:
- name: api-customer
url: /customer/v3/api-docs
- name: api-cart
url: /cart/v3/api-docs
- name: api-product
url: /product/v3/api-docs
For each µservice you have to fill in the url property with is the url to the openAPI definition at json or yaml format.
For springdoc library which uses openAPI 3.0 the default url is /${µServiceContextPath}/v3/api-docs
For springfox library which uses openAPI 2.0 the default url is /${µServiceContextPath}/v2/api-docs
Finally access to /${contextPath}/swagger-ui.html and you will be able to select an openAPI