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kubectl_examples.md

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Kubectl examples

This document cover simple Kubectl operations, and how to solve some problems that you may experience.

Head over to getting started if you need help setting up Kubectl.

Kubectl runs operations on specific resources (just like an REST-api endpoint). So a lot of these commandoes works with different types of resources. To avoid redundant examples we have tried to make the operation-examples open, and the output-examples specific for one resource.

List resource

Typical resources to list are: pods, deployment, ingress, services

kubectl get <resource>

$ kubectl get pods
NAME                                                           READY     STATUS             RESTARTS   AGE
dagpenger-soknadvelger-86576554bb-tlswh                        1/1       Running            0          40d
dagpenger-soknadvelger-86576554bb-xhqng                        1/1       Running            0          40d
eessi-fagmodul-frontend-6d98fc4c8c-npvt9                       1/1       Running            0          48d
engangsstonad-68d85b988b-ln9zz                                 1/1       Running            0          6d
engangsstonad-68d85b988b-v9r4v                                 1/1       Running            0          6d

List resources with labels

There are different types of labels on each pod (and other resources). The main labels to search for are app, and team.

kubectl get <resource> --selector app=<appname>

$ kubectl get pods --selector app=dagpenger-soknadvelger
NAME                                      READY     STATUS    RESTARTS   AGE
dagpenger-soknadvelger-86576554bb-tlswh   1/1       Running   0          40d
dagpenger-soknadvelger-86576554bb-xhqng   1/1       Running   0          40d

--selector can be shortened to -l.

Check a pods logs

kubectl logs <pod-name>

The pods dosen't share logs, so we recommend looking at logs at logs.adeo.no.

See description/configuration of a resource

kubectl describe <resource> <resource-name>

$ kubectl describe deployment dagpenger-soknadvelger
Name:                   dagpenger-soknadvelger
Namespace:              default
CreationTimestamp:      Mon, 04 Jun 2018 22:40:19 +0200
Labels:                 app=dagpenger-soknadvelger
						team=dagpenger
# and a lot more...

Deleting a resource

Some resource get recreated when deleted, if you want to remove an app, use the /delete endpoint instead.

kubectl delete resource <resource-name>

$ delete pod nais-testapp-9747b9695-tc57h
pod "nais-testapp-9747b9695-tc57h" deleted

Undo a deployment (aka rollback)

kubectl rollout undo deployment <deployment-name>`

$ kubectl rollout undo deployment nais-testapp
deployment.apps "nais-testapp"
$ kubectl describe deployment nais-testapp
Name:                   nais-testapp
Namespace:              default
CreationTimestamp:      Fri, 13 Jul 2018 15:40:57 +0200
# more text between
Events:
  Type    Reason              Age                     From                   Message
  ----    ------              ----                    ----                   -------
  Normal  ScalingReplicaSet   <invalid> (x2 over 9d)  deployment-controller  Scaled up replica set nais-testapp-66b86cd59c to 1
  Normal  DeploymentRollback  <invalid>               deployment-controller  Rolled back deployment "nais-testapp" to revision 1

Namespaces

By default, your application will exist in its own namespace. Therefore you must specify this namespace for your kubectl operations.

Namespace flag

You can use the namespace flag on all kubectl operations:

kubectl get pods --namespace <namespace>

You can also use -n. This command will describe the deployment nais-testapp in the namespace t1:

kubectl describe deployment nais-testapp -n t1

List namespaces

To list all namespaces in the cluster:

kubectl get namespaces

Switch namespace

If you haven't specified anything, kubectl will operate in the namespace default.

You can tell kubectl to use another namespace if you don't want to append the namespace flag to all operations every time:

kubectl config set-context $(kubectl config current-context) --namespace=<insert-namespace-name-here>

Validate that the namespace is set:

kubectl config view | grep namespace: -B 1

If you have more than one cluster (e.g. preprod and prod), this will output both clusters:

$ kubectl config view | grep namespace: -B 1
	cluster: prod-sbs
	namespace: nais-testapp
--
	cluster: preprod-sbs
	namespace: t1

You can now run kubectl operations without specifying namespace.