`metrics(namespace)` | Returns a list of metrics in the namespace.
`dimension_keys(namespace)` | Returns a list of dimension keys in the namespace.
`dimension_values(region, namespace, metric, dimension_key)` | Returns a list of dimension values matching the specified `region`, `namespace`, `metric` and `dimension_key`.
`ebs_volume_ids(region, instance_id)` | Returns a list of volume id matching the specified `region`, `instance_id`.
`ec2_instance_attribute(region, attribute_name, filters)` | Returns a list of attribute matching the specified `region`, `attribute_name`, `filters`.
For details about the metrics CloudWatch provides, please refer to the [CloudWatch documentation](https://docs.aws.amazon.com/AmazonCloudWatch/latest/DeveloperGuide/CW_Support_For_AWS.html).
The `ec2_instance_attribute` query take `filters` in JSON format.
You can specify [pre-defined filters of ec2:DescribeInstances](http://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstances.html).