`AwsSmithyClientT` does not pass in `m_serviceName` param when initialising `endpointProvider`

[Renz456]

Describe the bug

We are trying to upgrade from SDK version 1.11.352 to 1.11.800 and noticed the following:
STS moved to AwsSmithyClientT; its generic initialization omitted m_serviceName, here: m_endpointProvider->InitBuiltInParameters(m_clientConfiguration);.

Endpoint configuration only consults AWS_ENDPOINT_URL_STS and global AWS_ENDPOINT_URL when a service name is supplied.

It looks like

• PR #3236 [release 1.11.483] introduced the Smithy Client initialising without service name.
• PR #3597 [release 1.11.685] added service-aware endpoint initialization and updated ordinary generated clients to pass SERVICE_NAME, but did not update the shared AwsSmithyClientT call.
• PR #3793 [release 1.11.790] Migrated STS from the legacy client to AwsSmithyClientT, making STS inherit the omission. This is where the observable STS regression began.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

STS clients created through AwsSmithyClientT should honor the standard AWS endpoint override configuration, including the
service-specific AWS_ENDPOINT_URL_STS environment variable and the global AWS_ENDPOINT_URL environment variable.

AwsSmithyClientT should pass its stored service name to the endpoint provider during initialization:

m_endpointProvider->InitBuiltInParameters(
    m_clientConfiguration,
    m_serviceName
);

This should make STS endpoint resolution behave consistently with the legacy STS client and other generated AWS service
clients.

Current Behavior

AwsSmithyClientT::initClient() calls the one-argument overload:

m_endpointProvider->InitBuiltInParameters(m_clientConfiguration);

Because the stored service name is not supplied, the endpoint provider does not resolve AWS_ENDPOINT_URL_STS or the
global AWS_ENDPOINT_URL.

Starting with 1.11.790, STS uses AwsSmithyClientT, so STS requests ignore these environment-configured endpoint overrides
and instead use the normal AWS STS endpoint. Explicitly setting ClientConfiguration::endpointOverride is unaffected.

Reproduction Steps

  #include <memory>
  #include <string>

  #include <aws/core/Aws.h>
  #include <aws/core/auth/AWSCredentials.h>
  #include <aws/core/client/GenericClientConfiguration.h>
  #include <aws/core/utils/memory/stl/AWSString.h>
  #include <aws/sts/STSClient.h>
  #include <aws/sts/STSEndpointProvider.h>
  #include <gtest/gtest.h>

  namespace {

  class AwsApi final {
    public:
      AwsApi() {
          Aws::InitAPI(options);
      }

      ~AwsApi() {
          Aws::ShutdownAPI(options);
      }

    private:
      Aws::SDKOptions options;
  };

  class RecordingStsEndpointProvider final
      : public Aws::STS::Endpoint::STSEndpointProvider {
    public:
      void InitBuiltInParameters(
          const Aws::Client::GenericClientConfiguration& config
      ) override {
          ++generic_init_calls;
          Aws::STS::Endpoint::STSEndpointProvider::
              InitBuiltInParameters(config);
      }

      void InitBuiltInParameters(
          const Aws::Client::GenericClientConfiguration& config,
          const Aws::String& service_name
      ) override {
          ++service_init_calls;
          initialized_service_name = service_name.c_str();

          Aws::STS::Endpoint::STSEndpointProvider::
              InitBuiltInParameters(config, service_name);
      }

      int generic_init_calls = 0;
      int service_init_calls = 0;
      std::string initialized_service_name;
  };

  TEST(
      AwsStsEndpointInitializationTest,
      SmithyClientPassesServiceNameToEndpointProvider
  ) {
      AwsApi aws_api;
      auto endpoint_provider =
          std::make_shared<RecordingStsEndpointProvider>();

      const Aws::Auth::AWSCredentials credentials(
          "test-access-key",
          "test-secret-key"
      );
      const Aws::Client::GenericClientConfiguration config;

      const Aws::STS::STSClient client(
          credentials,
          endpoint_provider,
          config
      );

      EXPECT_EQ(endpoint_provider->service_init_calls, 1);
      EXPECT_EQ(endpoint_provider->generic_init_calls, 0);
      EXPECT_EQ(endpoint_provider->initialized_service_name, "sts");
  }

  }  // namespace

Possible Solution

Would changing the call in AwsSmithyClientT::initClient() to the following be the intended fix?

  m_endpointProvider->InitBuiltInParameters(
       m_clientConfiguration,
       m_serviceName

Additional Information/Context

No response

AWS CPP SDK version used

1.11.800

Compiler and Version used

GCC/G++ 12.3.0

Operating System and version

Debian GNU/Linux 12 (bookworm)

[sbiscigl]

Hey @Renz456 thanks for opening the issue, and i think you are completely correct, running a simple test

#include <aws/core/Aws.h>
#include <aws/sts/STSClient.h>

using namespace Aws;
using namespace Aws::STS;

auto main() -> int {
  SDKOptions options{};
  options.loggingOptions.logLevel = Utils::Logging::LogLevel::Debug;
  InitAPI(options);
  {
    STSClient sts_client{};
    const auto identity = sts_client.GetCallerIdentity();
  }
  ShutdownAPI(options);
  return 0;
}

with AWS_ENDPOINT_URL_STS=foobar i see it not working/working before and after your change. it seems that when we added support for service specific endpoints we missed smithy based clients. saw you opened a PR lemme take a look at it.

[sbiscigl]

just as a heads up where we're with it, from running your suggested change on CI it tugged at a thread that showed a lot more was broken then previously thought, so updated your PR with a commit that will address that, after a successful CI run we should be able to merge it

[Renz456]

Thank you for the quick response + fix :)