Additional logging for logging the classes and classloaders of the IA…

…MClientCallbackHandler and the AWSCredentialsCallback classes. (#38)

* Enable support for STS regional endpoints when configured to assume a role

In AWS VPCs without internet access which have the STS VPC endpoint created the region needs to be explicitly along with the environment variable AWS_STS_REGIONAL_ENDPOINTS=regional otherwise the AWS Java SDK will use the global STS endpoint.

* Additional logging for logging the classes and classloaders of the IAMClientCallbackHandler and the AWSCredentialsCallback classes.

Co-authored-by: Dan Vulpe <dvulpe@gmail.com>

src/main/java/software/amazon/msk/auth/iam/IAMClientCallbackHandler.java

@@ -69,10 +69,15 @@ public void close() {
  @Override
  public void handle(@NonNull Callback[] callbacks) throws IOException, UnsupportedCallbackException {
  for (Callback callback : callbacks) {
+ if (log.isDebugEnabled()) {
+ log.debug("Type information for callback: " + debugClassString(callback.getClass()) + " from "
+ + debugClassString(this.getClass()));
+ }
  if (callback instanceof AWSCredentialsCallback) {
  handleCallback((AWSCredentialsCallback) callback);
  } else {
- String message = "Unsupported callback type:" + callback.getClass().getName();
+ String message = "Unsupported callback type: " + debugClassString(callback.getClass()) + " from "
+ + debugClassString(this.getClass());
  //We are breaking good practice and logging as well as throwing since this is where client side
  //integrations might have trouble. Depending on the client framework either logging or throwing might
  //surface the error more easily to the user.
@@ -82,6 +87,10 @@ public void handle(@NonNull Callback[] callbacks) throws IOException, Unsupporte
  }
  }
 
+ protected static String debugClassString(Class<?> clazz) {
+ return "class: " + clazz.getName() + " classloader: " + clazz.getClassLoader().toString();
+ }
+
  protected void handleCallback(AWSCredentialsCallback callback) throws IOException {
  if (log.isDebugEnabled()) {
  log.debug("Selecting provider {} to load credentials", provider.getClass().getName());

src/test/java/software/amazon/msk/auth/iam/IAMClientCallbackHandlerTest.java

@@ -66,5 +66,13 @@ public void testDifferentCallback() {
  assertTrue(callbackException.getMessage().startsWith("Unsupported"));
  }
 
+ @Test
+ public void testDebugClassString() {
+ String debug1 = IAMClientCallbackHandler.debugClassString(this.getClass());
+ assertTrue(debug1.contains("software.amazon.msk.auth.iam.IAMClientCallbackHandlerTest"));
+ IAMClientCallbackHandler clientCallbackHandler = new IAMClientCallbackHandler();
+ String debug2 = IAMClientCallbackHandler.debugClassString(clientCallbackHandler.getClass());
+ assertTrue(debug2.contains("software.amazon.msk.auth.iam.IAMClientCallbackHandler"));
+ }
 
 }