Spring boot 3 access to /.well-known/openid-configuration from docker times out

Setup:

Docker swarm 3 nodes (all instances in same network)
1 nginx instance
- redirecting oauth.*** to eureka-server cluster
- other dns redirects
2 eureka instances redirecting oauth.*** calls to authorisation server
1 authorisation server (oidc)
1 resource server (some crud service)
- Using following property in application.properties
```
spring.security.oauth2.resourceserver.jwt.issuer-uri=https://oauth.b2beyond.org/
```
All services are on the same swarm network

The authorisation server is accessible from browser : https://oauth.b2beyond.org/.well-known/openid-configuration

When resource server tries to access this url from within it's container; we receive following exception:

org.springframework.security.oauth2.jwt.JwtDecoderInitializationException: Failed to lazily resolve the supplied JwtDecoder instance
    at org.springframework.security.oauth2.jwt.SupplierJwtDecoder.wrapException(SupplierJwtDecoder.java:58)
    at org.springframework.security.oauth2.jwt.SupplierJwtDecoder.decode(SupplierJwtDecoder.java:49)
    at org.springframework.security.oauth2.server.resource.authentication.JwtAuthenticationProvider.getJwt(JwtAuthenticationProvider.java:96)
    at org.springframework.security.oauth2.server.resource.authentication.JwtAuthenticationProvider.authenticate(JwtAuthenticationProvider.java:87)
    at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:182)
    at org.springframework.security.authentication.ObservationAuthenticationManager.lambda$authenticate$1(ObservationAuthenticationManager.java:53)
    at io.micrometer.observation.Observation.observe(Observation.java:559)
    at org.springframework.security.authentication.ObservationAuthenticationManager.authenticate(ObservationAuthenticationManager.java:52)
    at org.springframework.security.oauth2.server.resource.web.authentication.BearerTokenAuthenticationFilter.doFilterInternal(BearerTokenAuthenticationFilter.java:137)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:173)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:107)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:93)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:173)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:116)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:173)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:173)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.context.SecurityContextHolderFilter.doFilterInternal(SecurityContextHolderFilter.java:69)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:173)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:62)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:173)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.wrapFilter(ObservationFilterChainDecorator.java:185)
    at org.springframework.security.web.ObservationFilterChainDecorator$AroundFilterObservation$SimpleAroundFilterObservation.lambda$wrap$0(ObservationFilterChainDecorator.java:278)
    at org.springframework.security.web.ObservationFilterChainDecorator$ObservationFilter.doFilter(ObservationFilterChainDecorator.java:170)
    at org.springframework.security.web.ObservationFilterChainDecorator$VirtualFilterChain.doFilter(ObservationFilterChainDecorator.java:134)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:233)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:191)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:351)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.ServerHttpObservationFilter.doFilterInternal(ServerHttpObservationFilter.java:109)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.ForwardedHeaderFilter.doFilterInternal(ForwardedHeaderFilter.java:153)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:177)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:119)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:400)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:859)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1734)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: Unable to resolve the Configuration with the provided Issuer of "https://oauth.b2beyond.org"
    at org.springframework.security.oauth2.jwt.JwtDecoderProviderConfigurationUtils.getConfiguration(JwtDecoderProviderConfigurationUtils.java:161)
    at org.springframework.security.oauth2.jwt.JwtDecoderProviderConfigurationUtils.getConfigurationForIssuerLocation(JwtDecoderProviderConfigurationUtils.java:79)
    at org.springframework.security.oauth2.jwt.JwtDecoders.fromIssuerLocation(JwtDecoders.java:93)
    at org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerJwtConfiguration$JwtDecoderConfiguration.lambda$jwtDecoderByIssuerUri$3(OAuth2ResourceServerJwtConfiguration.java:141)
    at org.springframework.security.oauth2.jwt.SupplierJwtDecoder.decode(SupplierJwtDecoder.java:46)

    ... 85 more
Caused by: org.springframework.web.client.ResourceAccessException: I/O error on GET request for "https://oauth.b2beyond.org/.well-known/openid-configuration": Operation timed out
    at org.springframework.web.client.RestTemplate.createResourceAccessException(RestTemplate.java:888)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:868)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:714)
    at org.springframework.security.oauth2.jwt.JwtDecoderProviderConfigurationUtils.getConfiguration(JwtDecoderProviderConfigurationUtils.java:150)

    ... 89 more
Caused by: java.net.ConnectException: Operation timed out
    at java.base/sun.nio.ch.Net.connect0(Native Method)
    at java.base/sun.nio.ch.Net.connect(Unknown Source)
    at java.base/sun.nio.ch.Net.connect(Unknown Source)
    at java.base/sun.nio.ch.NioSocketImpl.connect(Unknown Source)
    at java.base/java.net.SocksSocketImpl.connect(Unknown Source)
    at java.base/java.net.Socket.connect(Unknown Source)
    at java.base/sun.security.ssl.SSLSocketImpl.connect(Unknown Source)
    at java.base/sun.security.ssl.BaseSSLSocketImpl.connect(Unknown Source)
    at java.base/sun.net.NetworkClient.doConnect(Unknown Source)
    at java.base/sun.net.www.http.HttpClient.openServer(Unknown Source)
    at java.base/sun.net.www.http.HttpClient.openServer(Unknown Source)
    at java.base/sun.net.www.protocol.https.HttpsClient.<init>(Unknown Source)
    at java.base/sun.net.www.protocol.https.HttpsClient.New(Unknown Source)
    at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(Unknown Source)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(Unknown Source)
    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
    at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
    at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(Unknown Source)
    at org.springframework.http.client.SimpleBufferingClientHttpRequest.executeInternal(SimpleBufferingClientHttpRequest.java:75)
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48)
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:66)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:862)

    ... 91 more

Tried

using docker stack name -> not resolving the issue, making it worse, returning stack name as issuer
Adding dns property to docker compose file, no change
Adding /etc/hosts entry, no change
Using google dns lookup address (8.8.8.8)
nslookup works correctly with both docker dns and google dns
traceroute fails on both dns servers: returns until 30 this output (I assume there is the issue, but no idea how to solve that)

traceroute oauth.b2beyond.org
traceroute to oauth.b2beyond.org (145.239.2.57), 30 hops max, 46 byte packets
 1  *  *  *
 2  *  *  *
 3  *  *  *
 4  *  *  *
 5  *  *  *
 6  *  *  *
 7  *  *  *
 8  *  *  *
 9  *  *  *
10  *  *  *
11  *  *  *
12  *  *  *
13  *  *  *

Solution

To give an answer to my own question. By adding the following property in my application.properties I could obtain what I wanted, that is the client authorising against the oauth2 authorisation server.

spring.security.oauth2.resourceserver.jwt.jwk-set-uri=http://server-oauth:8000/oauth2/jwks

server-oauth:8000 points directly to the docker container containing the oauth server. It can now validate without calling the .well-known/openid-configuration endpoint.