CloudWatch Exporter

An exporter for Amazon CloudWatch, for Prometheus.

Building and running

mvn package to build.

java -jar target/cloudwatch_exporter-0.1-SNAPSHOT-jar-with-dependencies.jar 1234 example.json to run.

Credentials and permissions

The CloudWatch Exporter uses the AWS Java SDK, which offers a variety of ways to provide credentials. This includes the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables.

The cloudwatch:ListMetrics and cloudwatch:GetMetricStatistics IAM permissions are required.

Configuration

The configuration is in JSON, an example with common options:

{ 
  "region": "eu-west-1",
  "metrics": [
    {"aws_namespace": "AWS/ELB", "aws_metric_name": "RequestCount",
     "aws_dimensions": ["AvailabilityZone", "LoadBalancerName"], "aws_statistics": ["Sum"]},
  ]
}

Name	Description
region	Required. The AWS region to connect to.
metrics	Required. A list of CloudWatch metrics to retrieve and export
aws_namespace	Required. Namespace of the CloudWatch metric.
aws_metric_name	Required. Metric name of the CloudWatch metric.
aws_dimensions	Optional. Which dimension to fan out over.
aws_statistics	Optional. A list of statistics to retrieve, values can include Sum, SampleCount, Minimum, Maximum, Average. Defaults to all statistics.
delay_seconds	Optional. The newest data to request. Used to avoid collecting data that has not fully converged. Defaults to 300s. Can be set globally and per metric.
range_seconds	Optional. How far back to request data for. Useful for cases such as Billing metrics that are only set every few hours. Defaults to 600s. Can be set globally and per metric.
period_seconds	Optional. Period to request the metric for. Only the most recent data point is used. Defaults to 60s. Can be set globally and per metric.

The above config will export time series such as

# HELP aws_elb_request_count_sum CloudWatch metric AWS/ELB RequestCount Dimensions: ["AvailabilityZone","LoadBalancerName"] Statistic: Sum Unit: Count
# TYPE aws_elb_request_count_sum gauge
aws_elb_request_count_sum{job="aws_elb",load_balancer_name="mylb",availability_zone="eu-west-1c",} 42.0
aws_elb_request_count_sum{job="aws_elb",load_balancer_name="myotherlb",availability_zone="eu-west-1c",} 7.0

All metrics are exported as gauges.

Timestamps from CloudWatch are not passed to Prometheus, pending resolution of #398. CloudWatch has been observed to sometimes take minutes for reported values to converge. The default delay_seconds will result in data that is at least 5 minutes old being requested to mitigate this.

In addition cloudwatch_exporter_scrape_error will be non-zero if an error occurred during the scrape, and cloudwatch_exporter_scrape_duration_seconds contains the duration of that scrape.

Cost

Amazon charges for every API request, see the current charges.

Every metric retrieved requires one API request, which can include multiple statistics. In addition, when aws_dimensions is provided, the exporter needs to do API requests to determine what metrics to request. This should be negligible compared to the requests for the metrics themselves.

If you have 100 API requests every minute, with the price of USD$10 per million requests (as of Jan 2015), that is around $45 per month. The cloudwatch_requests_total counter tracks how many requests are being made.

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