SDK support for Proxy requiring Kerberos auth

[PankajSAgarwal]

Describe the feature

AWS SDK2 Java does not provide ability to authenticate to AWS STS via proxy that requires Kerberos Authentication.

Use Case

Need to connect from on-prem to AWS STS API via proxy which requires Kerberos authentication .

We have run into a limitation of the AWS SDK ApacheHttpClient which doesn’t allow for customization of the builder:
https://github.com/aws/aws-sdk-java-v2/blob/2.20.156/http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ApacheHttpClient.java#L153
which is required for us to configure the setDefaultAuthSchemeRegistry and setDefaultCredentialsProvider:

Proposed Solution

As a workaround we implemented a forked implementation of the AWS ApacheHttpClient to override the AuthSchemeProvider which will consider canonicalHostName of proxy by default for kerberos authemtication .

We added below code snippet to the builder at the following line https://github.com/aws/aws-sdk-java-v2/blob/2.20.156/http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ApacheHttpClient.java#L153

Registry<AuthSchemeProvider> authSchemeProviderRegistry = configuration.authSchemeProviderRegistry;
        if (authSchemeProviderRegistry == null) {
            authSchemeProviderRegistry = RegistryBuilder.<AuthSchemeProvider>create()
                    .register(AuthSchemes.BASIC, new BasicSchemeFactory())
                    .register(AuthSchemes.DIGEST, new DigestSchemeFactory())
                    .register(AuthSchemes.NTLM, new NTLMSchemeFactory())
                    .register(AuthSchemes.SPNEGO, new SPNegoSchemeFactory(true, false))
                    .register(AuthSchemes.KERBEROS, new KerberosSchemeFactory(true, false)).build();
        }
        builder.setDefaultAuthSchemeRegistry(authSchemeProviderRegistry);

We also had to use this system property in our application to make the kerberos negotiator work with AWS SDK Java 2 client

System.setProperty("javax.security.auth.useSubjectCredsOnly", "false");

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS Java SDK version used

aws sdk java v2

JDK version used

17 and 21

Operating System and version

Windows Server 2016 Standard/ Linux

[debora-ito]

@PankajSAgarwal I believe you submitted a Premium Support case with the same ask. As we said in the case, we've added this to our backlog.

For a similar feature request, we exposed the Apache HttpRoutePlanner attribute in the SDK ApacheHttpClient builder (javadocs). It's not exactly the feature you are asking for, but maybe you can use HttpRoutePlanner to redirect the flow to the authentication server?

[PankajSAgarwal]

@debora-ito , yes that is correct , I was advised by support personal on the case to raise a feature request for the same on Github.

[debora-ito]

I was advised by support personal on the case to raise a feature request for the same on Github.

Understood.

What about Apache HttpRoutePlanner, would it work for you?

[PankajSAgarwal]

I was advised by support personal on the case to raise a feature request for the same on Github.

Understood.

What about Apache HttpRoutePlanner, would it work for you?

HttpRoutePlanner will not work as well , HttpRoutePlanner can direct me to proxy and i can use basic authentication , but my requirement is to be able add kerberos Auth scheme for authentication to proxy , which HttpRoutePlanner doesn't seem to be supporting .

[debora-ito]

Support for this was added via #5874 and released in Java SDK version 2.30.20.

Now it's possible to configure the AuthSchemeProviderRegistry in the ApacheHttpClient builder, and KERBEROS is one of the AuthScheme options. Check our unit tests for some quick examples of use.