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Kubernetes/Kubectl

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kubectl is the Kubernetes command-line tool to deploy and manage applications on a Kubernetes cluster.

For tasks like doing deployments kubectl should not be used. Instead please refer to helm and helmfile.

On Debian 9 (also known as Debian Stretch) it is included in the package kubernetes-client.

kubectl can be used to view and troubleshoot cluster components and to do certain maintenance tasks. See also the kubectl cheatsheet/.

Setting KUBECONFIG

kubectl needs to know how to connect to the cluster and what credentials to use. This information can be stored in the kubeconfig file. By default kubectl uses a variable called KUBECONFIG to find this kubeconfig file. If the variable is not set, it looks in ~/.kube/config.[1]

In order to have kubectl working with your service the KUBECONFIG variable has to be set. This is of the form:

KUBECONFIG="/etc/kubernetes/${SERVICE}-${CLUSTER}.config"

It is easier to use kube_env for this purpose, see below.

Running kubectl Commands

For example to get a list of pods for a service:

KUBECONFIG="/etc/kubernetes/termbox-staging.config" kubectl get pods

Using kube_env

The tool kube_env (present on deploy hosts) simplifies the configuration of kubectl and the access to different clusters and services. Use the following command to setup the KUBECONFIG variable (and many other useful variables like namespace and helm variables):

kube_env $SERVICE $CLUSTER

Then you can use kubectl to access the service:

kubectl get pods

Describe a pod

If there is an issue with a pod not starting and logs don't say anything, use "describe" to get more info. For example:

kubectl describe pod P -n sessionstore

Also see