Spring doc oauth2RedirectUrl with wrong server

Question

I'm writing my first question, please be patient if anything is missing. Any Feedback is welcome.

We have an issue with the generated oauth2RedirectUrl after migrating from a Windows 2012 R2 to a Windows 2016. The server is no longer containing the alias name but the technical server name.

We are using Spring Boot 2.6.0 including spring-boot-starter-oauth2-resource-server and springdoc-openapi-ui 1.5.12. Spring Boot is set up as a resource server with JWT authorization with Azure OAuth2.

We deploy a FAT Jar on windows machines and recently changed to a new server. Each machine is has a DNS entry with a technical name and a human readable alias. Lets say

• human-readable-name1 for the old machine
• human-readable-name2 for the new machine

We deployed the exact same software on both machines. We access the sawagger ui with

https://human-readable-name1.domain:port/swagger-ui.html

and

https://human-readable-name2.domain:port/swagger-ui.html

The response from both machines include the generated api-docs which are looking fine. Containing on both machines like

"servers": [
        {
            "url": "https://human-readable-name.domain:port",
            "description": "Generated server url"
        }
    ]

But the swagger-config change

OLD

{
    "configUrl": "/v3/api-docs/swagger-config",
    "oauth2RedirectUrl": "https://human-readable-name1:port/swagger-ui/oauth2-redirect.html",
    "url": "/v3/api-docs",
    "validatorUrl": ""
}

NEW

{
    "configUrl": "/v3/api-docs/swagger-config",
    "oauth2RedirectUrl": "https://technicalname:port/swagger-ui/oauth2-redirect.html",
    "url": "/v3/api-docs",
    "validatorUrl": ""
}

This breaks the log in as the token is no longer reaching the swagger ui client.

Any suggestions where I even can start looking for the reason?

Swagger config:

@Configuration
class OpenApiConfig {

@Value("${springdoc.oAuthFlow.authorizationUrl}")
private String authorizationUrl;

@Value("${springdoc.oAuthFlow.tokenUrl}")
private String tokenUrl;

@Bean
public OpenAPI customOpenAPI() {
    return new OpenAPI()                
            .components(new Components()
                    .addSecuritySchemes("security_auth", 
                            new SecurityScheme()
                                .type(SecurityScheme.Type.OAUTH2)
                                .flows(new OAuthFlows()
                                        .authorizationCode(new OAuthFlow()
                                                .authorizationUrl(authorizationUrl)
                                                .tokenUrl(tokenUrl)
                                                .scopes(new Scopes()
                                                        .addString("xxx", "xxx")
                                                    )
                                            )
                                    )
                        )
                )
            .addSecurityItem(new SecurityRequirement().addList("security_auth"))
            ;
}

}

Spring Boot yaml

spring.security.oauth2.resourceserver.jwt:
  jwk-set-uri: https://login.microsoftonline.com/common/discovery/v2.0/keys
  issuer-uri: https://login.microsoftonline.com/xxx/v2.0

springdoc:
  swagger-ui:
    oauth:
      clientId: 'xxx'
      use-pkce-with-authorization-code-grant: true
  oAuthFlow:
    authorizationUrl: https://login.microsoftonline.com/xxx/oauth2/v2.0/authorize
    tokenUrl: https://login.microsoftonline.com/xxx/oauth2/v2.0/token