config.json

{
    "region": "us-west-1",
    "metrics": [
        {
            "aws_namespace": "AWS/S3", "aws_metric_name": "BucketSizeBytes",
            "aws_dimensions": ["BucketName", "StorageType"],
            "aws_dimension_select": {
                "BucketName": ["<redacted>"],
                "StorageType": ["StandardStorage"]
            }
        }
    ]
}

I'm having trouble collecting S3 stats with https://github.com/prometheus/cloudwatch_exporter.
I can get ELB stats, but S3 stats are just not reported, and no errors are generated.

The correct answer is: ask for non-default period/range:

{
    "region": "us-west-1",
    "metrics": [
        {
            "aws_namespace": "AWS/S3", "aws_metric_name": "BucketSizeBytes",
            "aws_dimensions": ["BucketName", "StorageType"],
            "aws_dimension_select": {
                "BucketName": ["redacted"],
                "StorageType": ["StandardStorage"]
            },
            "aws_statistics": ["Average"],
            "period_seconds":86400,
            "range_seconds":86400
        }
    ]
}