Default batch size incompatible with CloudWatchExportAutoConfiguration

[jmccance]

The CloudWatch metrics use the default batch size from StepRegistryProperties, which is 10000. The maximum batch size for CloudWatch metrics is 20.

This leads to this exception when the app tries to publish metrics:

com.amazonaws.services.cloudwatch.model.InvalidParameterValueException: The collection MetricData must not have a size greater than 20. (Service: AmazonCloudWatch; Status Code: 400; Error Code: InvalidParameterValue; Request ID: c3d34eb9-74c3-11e8-94a3-655359213eb6)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1632)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1304)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1058)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:743)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:717)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:699)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:667)
        at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:649)
        at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:513)
        at com.amazonaws.services.cloudwatch.AmazonCloudWatchClient.doInvoke(AmazonCloudWatchClient.java:1401)
        at com.amazonaws.services.cloudwatch.AmazonCloudWatchClient.invoke(AmazonCloudWatchClient.java:1377)
        at com.amazonaws.services.cloudwatch.AmazonCloudWatchClient.executePutMetricData(AmazonCloudWatchClient.java:1284)
        at com.amazonaws.services.cloudwatch.AmazonCloudWatchAsyncClient$15.call(AmazonCloudWatchAsyncClient.java:807)
        at com.amazonaws.services.cloudwatch.AmazonCloudWatchAsyncClient$15.call(AmazonCloudWatchAsyncClient.java:801)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

I was able to resolve this by manually setting management.metrics.export.cloudwatch.batchSize: 20 in application.yaml.

It would be nice if CloudWatchExportAutoConfiguration or CloudWatchProperties used a valid default.

Dependency	Version
spring-cloud	Finchley.RELEASE
spring-cloud-aws-autoconfigure	2.0.0.RELEASE
micrometer-registry-cloudwatch	1.0.5