CloudWatch Exporter

A Prometheus exporter for Amazon CloudWatch.

Alternatives

For ECS workloads, there is also an ECS exporter.

For a different approach to CloudWatch metrics, with automatic discovery, consider Yet Another CloudWatch Exporter (YACE).

Building and running

Cloudwatch Exporter requires at least Java 11.

mvn package to build.

java -jar target/cloudwatch_exporter-*-SNAPSHOT-jar-with-dependencies.jar 9106 example.yml to run.

The most recent pre-built JAR can be found at http://search.maven.org/#search%7Cga%7C1%7Ca%3A%22cloudwatch_exporter%22

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, cloudwatch:GetMetricStatistics and cloudwatch:GetMetricData IAM permissions are required. The tag:GetResources IAM permission is also required to use the aws_tag_select feature.

Configuration

The configuration is in YAML.

An example with common options and aws_dimension_select:

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

A similar example with common options and aws_tag_select:

---
region: eu-west-1
metrics:
 - aws_namespace: AWS/ELB
   aws_metric_name: RequestCount
   aws_dimensions: [AvailabilityZone, LoadBalancerName]
   aws_tag_select:
     tag_selections:
       Monitoring: ["enabled"]
     resource_type_selection: "elasticloadbalancing:loadbalancer"
     resource_id_dimension: LoadBalancerName
   aws_statistics: [Sum]

Note: configuration examples for different namespaces can be found in examples directory

Note: A configuration builder can be found here.

Name	Description
region	Optional. The AWS region to connect to. If none is provided, an attempt will be made to determine the region from the default region provider chain.
role_arn	Optional. The AWS role to assume. Useful for retrieving cross account metrics.
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	Required. This should contain exactly all the dimensions available for a metric. Run aws cloudwatch list-metrics to find out which dimensions you need to include for your metric.
aws_dimension_select	Optional. Which dimension values to filter. Specify a map from the dimension name to a list of values to select from that dimension.
aws_dimension_select_regex	Optional. Which dimension values to filter on with a regular expression. Specify a map from the dimension name to a list of regexes that will be applied to select from that dimension.
aws_tag_select	Optional. A tag configuration to filter on, based on mapping from the tagged resource ID to a CloudWatch dimension.
tag_selections	Optional, under aws_tag_select. Specify a map from a tag key to a list of tag values to apply tag filtering on resources from which metrics will be gathered.
resource_type_selection	Required, under aws_tag_select. Specify the resource type to filter on. resource_type_selection should be comprised as service:resource_type, as per the resource group tagging API. Where resource_type could be an empty string, like in S3 case: resource_type_selection: "s3:".
resource_id_dimension	Required, under aws_tag_select. For the current metric, specify which CloudWatch dimension maps to the ARN resource ID.
arn_resource_id_regexp	If the Cloudwatch dimension specified in resource_id_dimension doesn't conform to the convention for resource ID an alternative regular expression to extract the resource ID from the ARN can be given here. The default is `(?:([^:/]+)
aws_statistics	Optional. A list of statistics to retrieve, values can include Sum, SampleCount, Minimum, Maximum, Average. Defaults to all statistics unless extended statistics are requested.
aws_extended_statistics	Optional. A list of extended statistics to retrieve. Extended statistics currently include percentiles in the form pN or pN.N.
delay_seconds	Optional. The newest data to request. Used to avoid collecting data that has not fully converged. Defaults to 600s. 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.
set_timestamp	Optional. Boolean for whether to set the Prometheus metric timestamp as the original Cloudwatch timestamp. For some metrics which are updated very infrequently (such as S3/BucketSize), Prometheus may refuse to scrape them if this is set to true (see #100). Defaults to true. Can be set globally and per metric.
use_get_metric_data	Optional. Boolean (experimental) Use GetMetricData API to get metrics instead of GetMetricStatistics. Can be set globally and per metric.
list_metrics_cache_ttl	Optional. Number of seconds to cache the result of calling the ListMetrics API. Defaults to 0 (no cache). Can be set globally and per metric.
warn_on_empty_list_dimensions	Optional. Boolean Emit warning if the exporter cannot determine what metrics to request

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",instance="",load_balancer_name="mylb",availability_zone="eu-west-1c",} 42.0
aws_elb_request_count_sum{job="aws_elb",instance="",load_balancer_name="myotherlb",availability_zone="eu-west-1c",} 7.0

If the aws_tag_select feature was used, an additional information metric will be exported for each AWS tagged resource matched by the resource type selection and tag selection (if specified), such as

# HELP aws_resource_info AWS information available for resource
# TYPE aws_resource_info gauge
aws_resource_info{job="aws_elb",instance="",arn="arn:aws:elasticloadbalancing:eu-west-1:121212121212:loadbalancer/mylb",load_balancer_name="mylb",tag_Monitoring="enabled",tag_MyOtherKey="MyOtherValue",} 1.0

aws_recource_info can be joined with other metrics using group_left in PromQL such as the following:

  aws_elb_request_count_sum
* on(load_balancer_name) group_left(tag_MyOtherKey)
  aws_resource_info

All metrics are exported as gauges.

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. cloudwatch_exporter_build_info contains labels referencing the current build version and build release date.

Build Info Metric

cloudwatch_exporter_build_info is a default cloudwatch exporter metric that contains the current cloudwatch exporter version and release date as label values. The numeric metric value is statically set to 1. If the metrics label values are "unknown" the build information scrap failed.

CloudWatch doesn't always report data

Cloudwatch reports data either always or only in some cases, example only if there is a non-zero value. The CloudWatch Exporter mirrors this behavior, so you should refer to the Cloudwatch documentation to find out if your metric is always reported or not.

Timestamps

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 10 minutes old being requested to mitigate this. The samples exposed will have the timestamps of the data from CloudWatch, so usual staleness semantics will not apply and values will persist for 5m for instant vectors.

In practice this means that if you evaluate an instant vector at the current time, you will not see data from CloudWatch. An expression such as aws_elb_request_count_sum offset 10m will allow you to access the data, and should be used in recording rules and alerts.

For certain metrics which update relatively rarely, such as from S3, set_timestamp should be configured to false so that they are not exposed with a timestamp. This is as the true timestamp from CloudWatch could be so old that Prometheus would reject the sample.

FAQ: I can see the metrics in /metrics but not in the Prometheus web console

The metrics will be visible in Prometheus if you look more than delay_seconds in the past. Try the graph view.

This is an unfortunate result of a fundamental mismatch between CloudWatch and Prometheus. CloudWatch metrics converge over time, that is, the value at time T can change up to some later time T+dT. Meanwhile, Prometheus assumes that once it has scraped a sample, that is the truth, and the past does not change.

To compensate for this, by default the exporter delays fetching metrics, that is, it only asks for data 10 minutes later, when almost all AWS services have converged. It also reports to Prometheus that this sample is from the past. Because Prometheus, for an instant request, only looks back 5 minutes, it never sees any data "now".

Special handling for certain DynamoDB metrics

The DynamoDB metrics listed below break the usual CloudWatch data model.

• ConsumedReadCapacityUnits
• ConsumedWriteCapacityUnits
• ProvisionedReadCapacityUnits
• ProvisionedWriteCapacityUnits
• ReadThrottleEvents
• WriteThrottleEvents

When these metrics are requested in the TableName dimension CloudWatch will return data only for the table itself, not for its Global Secondary Indexes. Retrieving data for indexes requires requesting data across both the TableName and GlobalSecondaryIndexName dimensions. This behaviour is different to that of every other CloudWatch namespace and requires that the exporter handle these metrics differently to avoid generating duplicate HELP and TYPE lines.

When exporting one of the problematic metrics for an index the exporter will use a metric name in the format aws_dynamodb_METRIC_index_STATISTIC rather than the usual aws_dynamodb_METRIC_STATISTIC. The regular naming scheme will still be used when exporting these metrics for a table, and when exporting any other DynamoDB metrics not listed above.

Reloading Configuration

There are two ways to reload configuration:

1. Send a SIGHUP signal to the pid: kill -HUP 1234
2. POST to the reload endpoint: curl -X POST localhost:9106/-/reload

If an error occurs during the reload, check the exporter's log output.

Cost

Amazon charges for every CloudWatch API request or for every Cloudwatch metric requested, see the current charges.

• In case of using GetMetricStatistics (default) - 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.

In the case that all aws_dimensions are provided in the aws_dimension_select list, the exporter will not perform the above API request. It will request all possible combination of values for those dimensions. This will reduce cost as the values for the dimensions do not need to be queried anymore, assuming that all possible value combinations are present in CloudWatch.

If you have 100 API requests every minute, with the price of USD$10 per million requests (as of Aug 2018), that is around $45 per month. The cloudwatch_requests_total counter tracks how many requests are being made.

When using the aws_tag_select feature, additional requests are made to the Resource Groups Tagging API, but these are free. The tagging_api_requests_total counter tracks how many requests are being made for these.

Experimental GetMetricData

We are transitioning to use GetMetricsData instead of GetMetricsStatistics. The benefits of using GetMetricsData is mainly around much better performence.

Please refer to this doc explaining why it is best practice to use GetMetricData

API	performence	Costs	Stability
GetMetricStatistics	May be slow at scale	Charged per API request	stable. (Default option)
GetMetricData	Can retrieve data faster at scale	Charged per metric requested	New (opt-in via configuration)

Transition plan

At first this feature would be opt-in to allow you to decide when and how to test it On later versions we would swap the default so everyone can enjoy the benefits.

Cloudwatch exporter also expose a new self metric called cloudwatch_metrics_requested_total that allows you to track number of requested metrics in addition to the number of API requests.

Docker Images

To run the CloudWatch exporter on Docker, you can use the image from

• prom/cloudwatch-exporter
• quay.io/prometheus/cloudwatch-exporter

The available tags are

• main: snapshot updated on every push to the main branch
• latest: the latest released version
• vX.Y.Z: the specific version X.Y.Z. Note that up to version 0.11.0, the format was cloudwatch-exporter_X.Y.Z.

The image exposes port 9106 and expects the config in /config/config.yml. To configure it, you can bind-mount a config from your host:

docker run -p 9106 -v /path/on/host/config.yml:/config/config.yml quay.io/prometheus/cloudwatch-exporter

Specify the config as the CMD:

docker run -p 9106 -v /path/on/host/us-west-1.yml:/config/us-west-1.yml quay.io/prometheus/cloudwatch-exporter /config/us-west-1.yml

Or create a config file named config.yml along with following Dockerfile in the same directory and build it with docker build:

FROM prom/cloudwatch-exporter
ADD config.yml /config/