Stupid Kubectl Tricks, Kubecon 2017

A whirlwind tour of some of the most useful, interesting, and under-sold features the Kubernetes command-line has to offer.

Transcript

1. Stupid Kubectl Tricks Jordan Liggitt, @liggitt, Red Hat
2. 1. Personality Test
3. 1. Personality Test “kubectl”
4. 1. Personality Test kube·con·trol engineer control freak kube control to Major Tom
5. 1. Personality Test kube·cut·tle scary operations expert 8 arms. 2 tentacles. 0 pets.
6. 1. Personality Test kube·ee·cud·dle open-source hippie live. love. linux.
7. 1. Personality Test <anything else> special snowflake just like everyone else
9. 2. Autocomplete $ source <(kubectl completion bash)
10. alpha cluster-info describe annotate completion drain api-versions config edit apply convert exec attach cordon explain 2. Autocomplete $ kubectl ▋
11. certificatesigningrequest ingress configmap networkpolicy cronjob persistentvolume daemonset persistentvolumeclaim endpoints poddisruptionbudget horizontalpodautoscaler podtemplate $ kubectl get ▋ 2. Autocomplete
12. --all-namespaces --allow-missing-template-keys --alsologtostderr --as-group= --as= 2. Autocomplete $ kubectl get horizontalpodautoscaler --▋
13. $ kubectl get pods --all-namespaces GET /api/v1/pods 3. Trace logging
14. $ kubectl run pi --schedule="0/5 * * * ?" \ --image=perl --restart=OnFailure \ -- perl -Mbignum=bpi -wle 'print bpi(2000)' 3. Trace logging
15. -v 3. Trace logging
16. $ kubectl run -v=6 pi --schedule="0/5 * * * ?" \ --image=perl --restart=OnFailure \ -- perl -Mbignum=bpi -wle 'print bpi(2000)' POST /apis/batch/v1beta1/namespaces/default/cronjobs 3. Trace logging
17. $ kubectl run -v=7 pi --schedule="0/5 * * * ?" \ --image=perl --restart=OnFailure \ -- perl -Mbignum=bpi -wle 'print bpi(2000)' … Request Headers: User-Agent: kubectl/v1.9.0 (darwin/amd64) Accept: application/json, */* Content-Type: application/json 3. Trace logging
18. $ kubectl run -v=8 pi --schedule="0/5 * * * ?" \ --image=perl --restart=OnFailure \ -- perl -Mbignum=bpi -wle 'print bpi(2000)' … Request Body: {"kind":"CronJob","apiVersion":"batch/ v1beta1","metadata":{"name":"pi",… … Response Body: {"kind":"CronJob","apiVersion":"batch/ v1beta1","metadata":{"name":"pi",… 3. Trace logging
19. $ kubectl run -v=9 pi --schedule="0/5 * * * ?" \ --image=perl --restart=OnFailure \ -- perl -Mbignum=bpi -wle 'print bpi(2000)' curl -k -v -XPOST -H "Accept: application/json, */*" -H "Content-Type: application/json" -H "User-Agent: kubectl/v1.9.0 (darwin/amd64) kubernetes/94645c4" https://localhost:6443/apis/batch/v1beta1/namespaces/ default/cronjobs 3. Trace logging
20. 3. Trace logging
21. $ kubectl get deployments/mydep -o yaml kind: Deployment apiVersion: ¯\_(ツ)_/¯ metadata: name: mydep … 4. Qualified Resources
22. $ kubectl get <resource> $ kubectl get <resource>.<group> $ kubectl get <resource>.<version>.<group> 4. Qualified Resources
23. $ kubectl get deployments $ kubectl get deployments.apps $ kubectl get deployments.v1.apps 4. Qualified Resources
24. 5. Conversion apiVersion: autoscaling/v1 kind: HorizontalPodAutoscaler metadata: name: apache spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment name: apache minReplicas: 1 maxReplicas: 10 targetCPUUtilizationPercentage: 50
25. $ sed s#autoscaling/v1#autoscaling/v2beta1# 5. Conversion
26. 5. Conversion
27. apiVersion: autoscaling/v2beta1 kind: HorizontalPodAutoscaler metadata: name: apache spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment name: apache minReplicas: 1 maxReplicas: 10 metrics: - type: Resource resource: name: cpu targetAverageUtilization: 50 5. Conversion apiVersion: autoscaling/v1 kind: HorizontalPodAutoscaler metadata: name: apache spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment name: apache minReplicas: 1 maxReplicas: 10 targetCPUUtilizationPercentage: 50
28. 5. Conversion $ kubectl convert --output-version=autoscaling/v2beta1
29. 6. Explain $ kubectl explain --recursive <resource>
30. 6. Explain $ kubectl explain --recursive hpa DESCRIPTION: configuration of a horizontal pod autoscaler. FIELDS: spec <Object> maxReplicas <integer> minReplicas <integer> scaleTargetRef <Object> …
31. 6. Explain $ kubectl explain --recursive hpa \ --api-version=autoscaling/v2beta1 DESCRIPTION: specification of a horizontal pod autoscaler. FIELDS: spec <Object> maxReplicas <integer> minReplicas <integer> metrics <[]Object> …
32. 6. Explain $ kubectl explain life the server doesn't have a resource type "life"
33. 7. Piping $ cat greeting Happy Thanksgiving! $ kubectl create configmap greeting --from-file=greeting configmap "greeting" created
34. 7. Piping $ cat greeting Merry Christmas! $ kubectl create configmap greeting --from-file=greeting Error from server: configmaps "greeting" already exists
35. 7. Piping $ kubectl create configmap greeting \ --from-file=greeting --dry-run --output json { "kind": "ConfigMap", "apiVersion": "v1", "metadata": {"name": "greeting"}, "data": {"greeting": " Merry Christmas!"} }
36. 7. Piping $ kubectl create configmap greeting \ --from-file=greeting --dry-run --output json \ | kubectl apply -f - configmap "greeting" configured
37. 8. Portable Kubeconfig $ kubectl config view apiVersion: v1 clusters: - cluster: certificate-authority: certificate-authority.crt server: https://stage.acme.com:6443 …
38. 8. Portable Kubeconfig $ kubectl config view --flatten > portable.kubeconfig apiVersion: v1 clusters: - cluster: certificate-authority-data: LS0tLS1CRUdJTiBDRVJU… server: https://stage.acme.com:6443 …
39. 9. Current Context $ kubectl config view --minify \ --output 'jsonpath={..server} {..namespace}' https://prod.acme.com:6443 mynamespace
40. 9. Current Context $ PS1="[\$( kubectl config view --minify \ --output 'jsonpath={..server} {..namespace}' )]\$ " [https://prod.acme.com:6443 mynamespace]$ ▋
41. Stupid Kubectl Tricks Jordan Liggitt, @liggitt, Red Hat http://bit.ly/stupid-kubectl-tricks