Springdoc: got 404 when open swagger-ui.html - spring-boot

Question

I got latest Spring Boot app and springdoc.swagger-ui on board.
<dependency>
<groupId>io.swagger</groupId>
<artifactId>swagger-annotations</artifactId>
<version>1.6.1</version>
</dependency>
<dependency>
<groupId>org.springdoc</groupId>
<artifactId>springdoc-openapi-ui</artifactId>
<version>1.2.32</version>
</dependency>
My application.properties contains springdoc.swagger-ui.path=/swagger-ui-openapi.html
When I run application via Intellij IDEA http://localhost:8080/swagger-ui-openapi.html brings me to http://localhost:8080/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config
and Swagger UI page loads successfully.
But if I start the app via command line: "java -jar my-app.jar", I got 404 in browser and Error in logs 'Circular view path [error]' when trying to reach http://localhost:8080/swagger-ui-openapi.html
and it redirrects me to http://localhost:8080/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config
javax.servlet.ServletException: Circular view path [error]: would dispatch back to the current handler URL [/error] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
However http://localhost:8080/v3/api-docs is reachable and schema is available at this address.
How can I fix this?

Answer 1

What worked in my case when your application is running behind a proxy, a load-balancer or in the cloud.
In your Spring Boot application make sure your application handles this header: X-Forwarded-For.
There are two ways to achieve this:
In your properties file add:
server.use-forward-headers=true
If this is not enough, Spring Framework provides a ForwardedHeaderFilter. You can register it as a Servlet Filter in your application by setting server.forward-headers-strategy is set to FRAMEWORK.
Since Spring Boot 2.2, this is the new property to handle reverse proxy headers:
In your properties file add
server.forward-headers-strategy=framework
And you can add the following bean to your application:
#Bean
ForwardedHeaderFilter forwardedHeaderFilter() {
return new ForwardedHeaderFilter();
}
If you already have static content on your root, and you don’t want it to be overridden by springdoc-openapi-ui configuration, you can just define a custom configuration of the swagger-ui, in order not to override the configuration of your files from in your context-root:
For example use in your properties file:
springdoc.swagger-ui.path= /swagger-ui/api-docs.html
ref:
https://springdoc.org/

Answer 2

For this problem, my conclusion is:
(1) Starting it in IDEA is fine
(2) Repackaging the jar with spring-boot-maven-plugin and starting it with 'java -jar' is fine as well.
(3) if I tried to starting with such as 'java -classpath ".:.conf" DemoApplication', it does not work.
So, for packaging, i use the spring-boot-maven-plugin.

Answer 3

You don't need swagger-annotations v1.6.1 dependency for springdoc-openapi;
By default, with springdoc you need no additonal settings of any ViewResolver.
You can have a look at some sample code:
https://github.com/springdoc/springdoc-openapi-demos