Multiple multi-lang edits to introduce logging and additional tests.

+ added `ENDPOINT_REGION` nested key for a simpler Cx experience
+ deduplicated, and improved, logic w.r.t. CredentialsProvider
construction to NOT swallow Exceptions

amazon-kinesis-client-multilang/src/main/java/software/amazon/kinesis/multilang/NestedPropertyKey.java

@@ -17,6 +17,7 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import com.amazonaws.regions.Regions;
 import com.google.common.base.CaseFormat;
 
 import lombok.AccessLevel;
@@ -47,6 +48,9 @@ public enum NestedPropertyKey {
      *     SIGNING_REGION ::= AWS_REGION
      * </pre>
      *
+     * It would be redundant to provide both this and {@link #ENDPOINT_REGION}.
+     *
+     * @see #ENDPOINT_REGION
      * @see <a href="https://docs.aws.amazon.com/general/latest/gr/rande.html">AWS Service endpoints</a>
      * @see <a href="https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-regions">Available Regions</a>
      */
@@ -60,6 +64,21 @@ void visit(final NestedPropertyProcessor processor, final String endpoint) {
         }
     },
 
+    /**
+     * Specify the region where service requests will be submitted. This
+     * region will determine both the service endpoint and signing region.
+     * <br/><br/>
+     * It would be redundant to provide both this and {@link #ENDPOINT}.
+     *
+     * @see #ENDPOINT
+     * @see <a href="https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-regions">Available Regions</a>
+     */
+    ENDPOINT_REGION {
+        void visit(final NestedPropertyProcessor processor, final String region) {
+            processor.acceptEndpointRegion(Regions.fromName(region));
+        }
+    },
+
     /**
      * External ids may be used when delegating access in a multi-tenant
      * environment, or to third parties.

amazon-kinesis-client-multilang/src/main/java/software/amazon/kinesis/multilang/NestedPropertyProcessor.java

@@ -14,28 +14,41 @@
  */
 package software.amazon.kinesis.multilang;
 
+import com.amazonaws.regions.Regions;
+
 /**
  * Defines methods to process {@link NestedPropertyKey}s.
  */
 public interface NestedPropertyProcessor {
 
-    /**
-     * Set the external id, an optional field to designate who can assume an IAM role.
-     *
-     * @param externalId external id used in the service call used to retrieve session credentials
-     */
-    void acceptExternalId(String externalId);
-
     /**
      * Set the service endpoint where requests are sent.
      *
      * @param serviceEndpoint the service endpoint either with or without the protocol
-     *      (e.g. https://sns.us-west-1.amazonaws.com or sns.us-west-1.amazonaws.com)
+     *      (e.g., https://sns.us-west-1.amazonaws.com, sns.us-west-1.amazonaws.com)
      * @param signingRegion the region to use for SigV4 signing of requests (e.g. us-west-1)
      *
+     * @see #acceptEndpointRegion(Regions)
      * @see <a href="https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/client/builder/AwsClientBuilder.EndpointConfiguration.html">
      *     AwsClientBuilder.EndpointConfiguration</a>
      */
     void acceptEndpoint(String serviceEndpoint, String signingRegion);
 
+    /**
+     * Set the service endpoint where requests are sent.
+     *
+     * @param region Region to be used by the client. This will be used to determine both the service endpoint
+     *      (e.g., https://sns.us-west-1.amazonaws.com) and signing region (e.g., us-west-1) for requests.
+     *
+     * @see #acceptEndpoint(String, String)
+     */
+    void acceptEndpointRegion(Regions region);
+
+    /**
+     * Set the external id, an optional field to designate who can assume an IAM role.
+     *
+     * @param externalId external id used in the service call used to retrieve session credentials
+     */
+    void acceptExternalId(String externalId);
+
 }

amazon-kinesis-client-multilang/src/main/java/software/amazon/kinesis/multilang/auth/KclSTSAssumeRoleSessionCredentialsProvider.java

@@ -65,19 +65,25 @@ public void refresh() {
     }
 
     @Override
-    public void acceptExternalId(final String externalId) {
-        builder.withExternalId(externalId);
+    public void acceptEndpoint(final String serviceEndpoint, final String signingRegion) {
+        final EndpointConfiguration endpoint = new EndpointConfiguration(serviceEndpoint, signingRegion);
+        final AWSSecurityTokenService stsClient = AWSSecurityTokenServiceClient.builder()
+                .withEndpointConfiguration(endpoint)
+                .build();
+        builder.withStsClient(stsClient);
     }
 
     @Override
-    public void acceptEndpoint(final String serviceEndpoint, final String signingRegion) {
-        final EndpointConfiguration endpoint = new EndpointConfiguration(serviceEndpoint, signingRegion);
-        final AWSSecurityTokenService stsClient =
-                AWSSecurityTokenServiceClient.builder()
-                        .withEndpointConfiguration(endpoint)
-                        .withRegion(Regions.fromName(signingRegion))
-                        .build();
+    public void acceptEndpointRegion(final Regions region) {
+        final AWSSecurityTokenService stsClient = AWSSecurityTokenServiceClient.builder()
+                .withRegion(region)
+                .build();
         builder.withStsClient(stsClient);
     }
 
+    @Override
+    public void acceptExternalId(final String externalId) {
+        builder.withExternalId(externalId);
+    }
+
 }

amazon-kinesis-client-multilang/src/main/java/software/amazon/kinesis/multilang/config/AWSCredentialsProviderPropertyValueDecoder.java

@@ -14,7 +14,7 @@
  */
 package software.amazon.kinesis.multilang.config;
 
-import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -84,41 +84,35 @@ private static List<AWSCredentialsProvider> getValidCredentialsProviders(List<St
                 }
                 clazz = (Class<? extends AWSCredentialsProvider>) c;
             } catch (ClassNotFoundException cnfe) {
+                // Providers are a product of prefixed Strings to cover multiple
+                // namespaces (e.g., "Foo" -> { "some.auth.Foo", "kcl.auth.Foo" }).
+                // It's expected that many class names will not resolve.
                 continue;
             }
+            log.info("Attempting to construct {}", clazz);
 
             AWSCredentialsProvider provider = null;
             if (nameAndArgs.length > 1) {
                 final String[] varargs = Arrays.copyOfRange(nameAndArgs, 1, nameAndArgs.length);
 
                 // attempt to invoke an explicit N-arg constructor of FooClass(String, String, ...)
-                try {
+                provider = constructProvider(providerName, () -> {
                     Class<?>[] argTypes = new Class<?>[nameAndArgs.length - 1];
                     Arrays.fill(argTypes, String.class);
-                    Constructor<? extends AWSCredentialsProvider> c = clazz.getConstructor(argTypes);
-                    provider = c.newInstance(varargs);
-                } catch (Exception e) {
-                    log.debug("Can't find any credentials provider matching {}.", providerName);
-                }
+                    return clazz.getConstructor(argTypes).newInstance(varargs);
+                });
 
                 if (provider == null) {
                     // attempt to invoke a public varargs/array constructor of FooClass(String[])
-                    try {
-                        Constructor<? extends AWSCredentialsProvider> c = clazz.getConstructor(String[].class);
-                        provider = c.newInstance((Object) varargs);
-                    } catch (Exception e) {
-                        log.debug("Can't find any credentials provider matching {}.", providerName);
-                    }
+                    provider = constructProvider(providerName, () ->
+                        clazz.getConstructor(String[].class).newInstance((Object) varargs)
+                    );
                 }
             }
 
             if (provider == null) {
                 // regardless of parameters, fallback to invoke a public no-arg constructor
-                try {
-                    provider = clazz.newInstance();
-                } catch (Exception e) {
-                    log.debug("Can't find any credentials provider matching {}.", providerName);
-                }
+                provider = constructProvider(providerName, clazz::newInstance);
             }
 
             if (provider != null) {
@@ -158,4 +152,32 @@ private static List<String> getPossibleFullClassNames(final String provider) {
         ).map(prefix -> prefix + provider).collect(Collectors.toList());
     }
 
+    @FunctionalInterface
+    private interface CredentialsProviderConstructor<T extends AWSCredentialsProvider> {
+        T construct() throws IllegalAccessException, InstantiationException,
+                InvocationTargetException, NoSuchMethodException;
+    }
+
+    /**
+     * Attempts to construct an {@link AWSCredentialsProvider}.
+     *
+     * @param providerName Raw, unmodified provider name. Should there be an
+     *      Exeception during construction, this parameter will be logged.
+     * @param constructor supplier-like function that will perform the construction
+     * @return the constructed provider, if successful; otherwise, null
+     *
+     * @param <T> type of the CredentialsProvider to construct
+     */
+    private static <T extends AWSCredentialsProvider> T constructProvider(
+            final String providerName, final CredentialsProviderConstructor<T> constructor) {
+        try {
+            return constructor.construct();
+        } catch (NoSuchMethodException ignored) {
+            // ignore
+        } catch (IllegalAccessException | InstantiationException | InvocationTargetException | RuntimeException e) {
+            log.warn("Failed to construct {}", providerName, e);
+        }
+        return null;
+    }
+
 }

amazon-kinesis-client-multilang/src/main/java/software/amazon/kinesis/multilang/config/KinesisClientLibConfigurator.java

@@ -62,6 +62,7 @@ public KinesisClientLibConfigurator() {
     public MultiLangDaemonConfiguration getConfiguration(Properties properties) {
         properties.entrySet().forEach(e -> {
             try {
+                log.info("Processing (key={}, value={})", e.getKey(), e.getValue());
                 utilsBean.setProperty(configuration, (String) e.getKey(), e.getValue());
             } catch (IllegalAccessException | InvocationTargetException ex) {
                 throw new RuntimeException(ex);

amazon-kinesis-client-multilang/src/main/resources/multilang.properties

@@ -0,0 +1,93 @@
+# The script that abides by the multi-language protocol. This script will
+# be executed by the MultiLangDaemon, which will communicate with this script
+# over STDIN and STDOUT according to the multi-language protocol.
+executableName = sample_kclpy_app.py
+
+# The Stream arn: arn:aws:kinesis:<region>:<account id>:stream/<stream name>
+# Important: streamArn takes precedence over streamName if both are set
+streamArn = arn:aws:kinesis:us-east-5:000000000000:stream/kclpysample
+
+# The name of an Amazon Kinesis stream to process.
+# Important: streamArn takes precedence over streamName if both are set
+streamName = kclpysample
+
+# Used by the KCL as the name of this application. Will be used as the name
+# of an Amazon DynamoDB table which will store the lease and checkpoint
+# information for workers with this application name
+applicationName = MultiLangTest
+
+# Users can change the credentials provider the KCL will use to retrieve credentials.
+# The DefaultAWSCredentialsProviderChain checks several other providers, which is
+# described here:
+# http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/auth/DefaultAWSCredentialsProviderChain.html
+AWSCredentialsProvider = DefaultAWSCredentialsProviderChain
+
+# Appended to the user agent of the KCL. Does not impact the functionality of the
+# KCL in any other way.
+processingLanguage = python/3.8
+
+# Valid options at TRIM_HORIZON or LATEST.
+# See http://docs.aws.amazon.com/kinesis/latest/APIReference/API_GetShardIterator.html#API_GetShardIterator_RequestSyntax
+initialPositionInStream = TRIM_HORIZON
+
+# To specify an initial timestamp from which to start processing records, please specify timestamp value for 'initiatPositionInStreamExtended',
+# and uncomment below line with right timestamp value.
+# See more from 'Timestamp' under http://docs.aws.amazon.com/kinesis/latest/APIReference/API_GetShardIterator.html#API_GetShardIterator_RequestSyntax
+#initialPositionInStreamExtended = 1636609142
+
+# The following properties are also available for configuring the KCL Worker that is created
+# by the MultiLangDaemon.
+
+# The KCL defaults to us-east-1
+regionName = us-east-1
+
+# Fail over time in milliseconds. A worker which does not renew it's lease within this time interval
+# will be regarded as having problems and it's shards will be assigned to other workers.
+# For applications that have a large number of shards, this msy be set to a higher number to reduce
+# the number of DynamoDB IOPS required for tracking leases
+#failoverTimeMillis = 10000
+
+# A worker id that uniquely identifies this worker among all workers using the same applicationName
+# If this isn't provided a MultiLangDaemon instance will assign a unique workerId to itself.
+#workerId =
+
+# Shard sync interval in milliseconds - e.g. wait for this long between shard sync tasks.
+#shardSyncIntervalMillis = 60000
+
+# Max records to fetch from Kinesis in a single GetRecords call.
+#maxRecords = 10000
+
+# Idle time between record reads in milliseconds.
+#idleTimeBetweenReadsInMillis = 1000
+
+# Enables applications flush/checkpoint (if they have some data "in progress", but don't get new data for while)
+#callProcessRecordsEvenForEmptyRecordList = false
+
+# Interval in milliseconds between polling to check for parent shard completion.
+# Polling frequently will take up more DynamoDB IOPS (when there are leases for shards waiting on
+# completion of parent shards).
+#parentShardPollIntervalMillis = 10000
+
+# Cleanup leases upon shards completion (don't wait until they expire in Kinesis).
+# Keeping leases takes some tracking/resources (e.g. they need to be renewed, assigned), so by default we try
+# to delete the ones we don't need any longer.
+#cleanupLeasesUponShardCompletion = true
+
+# Backoff time in milliseconds for Amazon Kinesis Client Library tasks (in the event of failures).
+#taskBackoffTimeMillis = 500
+
+# Buffer metrics for at most this long before publishing to CloudWatch.
+#metricsBufferTimeMillis = 10000
+
+# Buffer at most this many metrics before publishing to CloudWatch.
+#metricsMaxQueueSize = 10000
+
+# KCL will validate client provided sequence numbers with a call to Amazon Kinesis before checkpointing for calls
+# to RecordProcessorCheckpointer#checkpoint(String) by default.
+#validateSequenceNumberBeforeCheckpointing = true
+
+# The maximum number of active threads for the MultiLangDaemon to permit.
+# If a value is provided then a FixedThreadPool is used with the maximum
+# active threads set to the provided value. If a non-positive integer or no
+# value is provided a CachedThreadPool is used.
+#maxActiveThreads = 0

amazon-kinesis-client-multilang/src/test/java/software/amazon/kinesis/multilang/MultiLangDaemonConfigTest.java

@@ -36,7 +36,7 @@
 
 @RunWith(MockitoJUnitRunner.class)
 public class MultiLangDaemonConfigTest {
-    private static final String FILENAME = "some.properties";
+    private static final String FILENAME = "multilang.properties";
     private static final String EXE = "TestExe.exe";
     private static final String APPLICATION_NAME = MultiLangDaemonConfigTest.class.getSimpleName();
     private static final String STREAM_NAME = "fakeStream";
@@ -52,7 +52,7 @@ public class MultiLangDaemonConfigTest {
     @Mock
     private AwsCredentials creds;
 
-    private KinesisClientLibConfigurator configurator;
+    private final KinesisClientLibConfigurator configurator = new KinesisClientLibConfigurator();
     private MultiLangDaemonConfig deamonConfig;
 
     /**
@@ -84,8 +84,6 @@ public void setup(String streamName, String streamArn) throws IOException {
 
         when(credentialsProvider.resolveCredentials()).thenReturn(creds);
         when(creds.accessKeyId()).thenReturn("cool-user");
-        configurator = new KinesisClientLibConfigurator();
-
         deamonConfig = new MultiLangDaemonConfig(FILENAME, classLoader, configurator);
     }
 
@@ -200,4 +198,9 @@ public void testPropertyValidation() {
         }
     }
 
+    @Test
+    public void testActualPropertiesFile() throws Exception {
+        new MultiLangDaemonConfig(FILENAME);
+    }
+
 }