Spring Security You cannot use .block() because it subscribes and does not have the security context as part of the subscriber context that is established by Spring Security's WebFilter.

    You cannot use `.block()` because it subscribes and does not have the security context as part of the subscriber context that is established by Spring Security's WebFilter.

If you believe this is a bug, please provide a complete and minimal sample (i.e. GitHub repository) of the problem with details on how to reproduce the issue, what you expect to happen, and what actually happens.

Originally posted by @rwinch in https://github.com/spring-projects/spring-security/issues/5207#issuecomment-603335544

I need to get the real token to pass it to minio. I have no idea how to achieve it.

more context:

I have sping-boot application with rest services written using Spring web flux.

For now I access minio using login/password authorizaton and it works fine.

For now I want to exchange application JWT token with STS minio token and I implemented method to test:

@PostMapping
public boolean test(JwtAuthenticationToken token) throws ServerException, InsufficientDataException, ErrorResponseException, IOException, NoSuchAlgorithmException, InvalidKeyException, InvalidResponseException, XmlParserException, InternalException {
    MinioClient minioClient =
            MinioClient.builder()
                    .region(...)
                    .endpoint(...)              
                    .credentialsProvider(new WebIdentityProvider(

                            () -> new Jwt(token.getToken().getTokenValue(), 1000),
                            String.valueOf(...),
                            null,
                            null,
                            null,
                            null,
                            null))
                    .build();
    return minioClient.bucketExists("mybucket").build());
}

This code successfully works and returns true because mybucket actually exists.

But it is only test and I need to move minioClient to the configuration. The issue here that I have to have credentials provider there.

So I've created folowing configuration:

@Bean
public MinioClient minioClient() {
    return MinioClient.builder()
            .region(...)
            .endpoint(...)
            .credentialsProvider(new WebIdentityProvider(

                    () -> {
                        String block = null;
                        try {
                            block = ReactiveSecurityContextHolder
                                .getContext()
                                .map(context -> {
                                            return context
                                                    .getAuthentication()
                                                    .getPrincipal();

                                        }
                                )
                                .cast(Jwt.class)
                                .map(Jwt::token)
                                .block();
                        } catch (Exception e) {
                            // it fails here     <=======
                            System.out.println(e);
                        }

                        Jwt jwt = new Jwt(String.valueOf(block),
                                1000);
                        return jwt; },
                    String.valueOf(...),
                    null,
                    null,
                    null,
                    null,
                    null))
            .build();
}

But unfortunately method block() fails with exception:

java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-6

Any ideas how to fix it?

Comment From: jzheaux

Thanks for getting in touch! It feels like this is a question that would be better suited to Stack Overflow. We prefer to use GitHub issues only for bugs and enhancements. Feel free to update this issue with a link to the re-posted question (so that other people can find it) or add more detail if you feel this is a genuine bug.

Comment From: gredwhite

Thanks for getting in touch! It feels like this is a question that would be better suited to Stack Overflow. We prefer to use GitHub issues only for bugs and enhancements. Feel free to update this issue with a link to the re-posted question (so that other people can find it) or add more detail if you feel this is a genuine bug.

I have already asked it in stackoverflow: https://stackoverflow.com/questions/74875058/how-to-get-jwt-token-value-in-spring-webflux-to-exchange-it-with-minio-sts-tok

But I want to know if it is bug or not from developers of spring-security(who else could know better ?) and if it is not a bug you definitely will be able to help me with my issue.