fixes #143 Correct the logic for max retries in the handler and config comment (#144)

Author: stevehu

lambda-invoker/src/main/java/com/networknt/aws/lambda/LambdaFunctionHandler.java

@@ -62,8 +62,12 @@ public LambdaFunctionHandler() {
         if(config.getMaxRetries() > 0) {
             overrideConfig = overrideConfig.toBuilder()
                     .retryStrategy(DefaultRetryStrategy.standardStrategyBuilder()
-                            .maxAttempts(config.getMaxRetries())
-                            .build())
+                    .maxAttempts(config.getMaxRetries() + 1) // +1 because the first attempt is not counted as a retry
+                    .build())
+                    .build();
+        } else {
+            overrideConfig = overrideConfig.toBuilder()
+                    .retryStrategy(DefaultRetryStrategy.doNotRetry())
                     .build();
         }
 

lambda-invoker/src/main/resources/config/lambda-invoker.yml

@@ -7,8 +7,9 @@ endpointOverride: ${lambda-invoker.endpointOverride:}
 apiCallTimeout: ${lambda-invoker.apiCallTimeout:60000}
 # Api call attempt timeout in milliseconds. This sets the amount of time for each individual attempt.
 apiCallAttemptTimeout: ${lambda-invoker.apiCallAttemptTimeout:20000}
-# The maximum number of retries for the Lambda function invocation. Default is 3. Set to 0 to disable retries.
-maxRetries: ${lambda-invoker.maxRetries:3}
+# The maximum number of retries for the Lambda function invocation. Default is 2, which equals to 3 max attempts.
+# Set to 0 to disable retries so that the Lambda function is invoked only once.
+maxRetries: ${lambda-invoker.maxRetries:2}
 # The maximum number of concurrent requests that can be made to Lambda. Default is 50.
 maxConcurrency: ${lambda-invoker.maxConcurrency:50}
 # The maximum number of pending acquires allowed. Default is 10000.