kube-cloudwatch-node-metrics

README

kube-cloudwatch-node-metrics

Emit AWS Cloudwatch metrics for Kubernetes node CPU usage for Autoscaling

kube-cloudwatch-node-metrics is a simple program that emits the percentage of CPU "reserved" on a Kubernetes node. It defines "reserved" CPU as the sum of all the compute resources of all the containers on a node. It uses requests if set, limits if requests is not set, and a default if neither are set.

kube-cloudwatch-node-metrics emits a single metric KubernetesCPUPercent in the Kubernetes Cloudwatch namespace every 60 seconds. This can be used for alerting and/or for configuring AWS autoscaling.

kube-cloudwatch-node-metrics should be run on each Kubernetes node. A daemonset is the preferred method. An example manifest is included.

Building and Using

This assumes you have enabled daemonsets in your Kubernetes cluster. The nodes also need permissions to describe instances, describe tags and push Cloudwatch metrics. A policy can be used, such as:

{
    "Version" : "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ec2:DescribeTags",
                "cloudwatch:PutMetricData"
            ],
            "Resource": "*"
            }
       ]
}

The simple way is to use the build script:

export DOCKER_REPO=my.docker.registry/mynamespace
docker login ${DOCKER_REPO}
./build.sh

This will build the binary and the Docker image. If DOCKER_REPO is set, it will also push to it.

Edit daemonset.json with the correct image information, and then create the daemonset using kubectl create -f daemonset.json.

Design

This initial version is extremely simple.

• It does not handle API authentication. It assumes you will be running kubectl proxy in the same pod.
• It does not use watches. It fetches the pods for the node on every run.
• It curently only uses the Kubernetes API. It could use the "pods" end point on the kubelet.
• It does not use the official Kubernetes Go API client. The official one has many dependencies and can challenging to build. This only uses a few structs, so doing it "by hand" is more straightforward.

TODO

LICENSE

see LICENSE

Authors

Written by the Engineering Team at Yik Yak