krs is a command line tool for capturing and serializing Kubernetes resource statistics in OpenMetrics format. It dumps statistics about Kubernetes resources, for example the number of pods in a certain namespace, on a periodic basis to local storage. The kind of resources (pods, services, etc.) as well as the scope, that is, cluster-level or a list of namespaces, is configurable. You can use krs either on the client-side (for example, from your laptop) or in-cluster, like in a deployment. Note that krs leaves the decision where and how long-term storage is carried out up to you. More …

Index:

• Install

• Use
• Testing

Install

In order to use krs you must meet the following two prerequisites:

• kubectl must be installed.
• Access to a Kubernetes cluster must be configured.

From binaries

You can download binaries for Linux, macOS, and Windows which are available via the release page. To install from binary, for example, on a macOS system, do:

$ curl -L $(curl -s https://api.github.com/repos/mhausenblas/krs/releases/latest | grep macos | grep browserdownloadurl | cut -d : -f 2,3 | tr -d \") -o krs
$ chmod +x krs
$ sudo mv krs /usr/local/bin

From source

Assuming you've got Go in version 1.10 or above installed you can install krs from source like so:

$ go get -u github.com/mhausenblas/krs

From Kubernetes

You can launch krs in Kubernetes using the launch.sh script as follows. The script will dynamically create the respective permissions for the namespace and run krs as a deployment. So, in a sense this is a self-test: create and watch a namespace krs-test and view the output like so:

$ kubectl create ns krs-test
namespace/krs-test created
$ ./launch.sh krs-test serviceaccount/krs created clusterrole.rbac.authorization.k8s.io/resreader configured rolebinding.rbac.authorization.k8s.io/allowpodprobes created deployment.apps/krs created
$ kubectl -n krs-test logs -f $(kubectl -n krs-test get po -l=run=krs --output=jsonpath={.items[*].metadata.name}) 
HELP pods Number of pods in any state, for example running
 
TYPE pods gauge
 pods{namespace="krs-test"} 1 
HELP deployments Number of deployments
 
TYPE deployments gauge
 deployments{namespace="krs-test"} 1 
HELP services Number of services
 
TYPE services gauge
 services{namespace="krs-test"} 0 ...

Use

krs assumes that kubectl is installed and configured. It writes the OpenMetrics data to stdout which you can then redirect to a file or process further.

For example, to gathers stats of the dev42 namespace and store the OpenMetrics formatted stats in a file called /tmp/krs/2018-10-05.om as well as see the errors on screen (via stdout), do the following:

$ krs --namespace dev42 >> /tmp/krs/2018-10-05.om

If you don't provide a namespace as the first argument, krs will watch the default namespace. Also, by default, the following resources are tracked: pods, deployments, and services.

For example, an excerpt of the output of the end-to-end test looks as follows:

# HELP pods Number of pods in any state, for example running
TYPE pods gauge
pods{namespace="krs"} 2
HELP deployments Number of deployments
TYPE deployments gauge
deployments{namespace="krs"} 2
HELP services Number of services
TYPE services gauge
services{namespace="krs"} 1
HELP pods Number of pods in any state, for example running
TYPE pods gauge
pods{namespace="krs"} 2
HELP deployments Number of deployments
TYPE deployments gauge
deployments{namespace="krs"} 2
HELP services Number of services
TYPE services gauge
services{namespace="krs"} 1
...

If you, for example, want to track pods, stateful sets, and persistent volumes in the namespace prod1337 you'd launch krs like so:

$ krs --namespace prod1337 --resources "pods,sts,pv,pvc"

There are two environment variables that krs understands:

• With KRSKUBECTLBIN you can define which kubectl binary krs will use. Note: under Windows this is required, for OpenShift, this is an option to use oc instead of kubectl.
• With KRS_VERBOSE set (for example, to true but really any value does) you can get debug-level information, down to what kubectl call has been issued.

• [ ] Improve Make file
• [ ] Complete e2e testing