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Summary - kubectl

Combine get, describe, apply and delete to manage resources.

Summary: kubectl

In this group:

  • Command form: kubectl VERB RESOURCE [NAME] [flags]; abbreviations: po, deploy, svc, ns, cm.
  • kubeconfig contexts select cluster/user/namespace (config use-context).
  • get (-o wide/yaml/name/jsonpath) lists; describe gives a summary and events; explain gives field docs.
  • apply -f declaratively creates/updates; diff and --dry-run check first.
  • delete deletes by name, file or label.
kubectl create deployment api --image=api:1.0 --dry-run=client -o yaml > api.yaml
kubectl apply -f api.yaml
kubectl describe deploy api

Practice A kubectl workflow

Write four commands: generate the YAML of an api deployment with the api:1.0 image into api.yaml without creating it; apply the file; show the api deployment in detail; list the pod names with -o name.

Starter code

terminal
# buraya yaz

Sample solution

terminal
kubectl create deployment api --image=api:1.0 --dry-run=client -o yaml > api.yaml
kubectl apply -f api.yaml
kubectl describe deploy api
kubectl get pods -o name

Expected output

deployment.apps/api created
Name:                   api
Replicas:               1 desired | 1 updated | 1 total | 1 available
pod/api-5d8f7c9b4-qrstu

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the first place to look to understand why a pod stays Pending?

  • The kubeconfig file
  • The Events in the kubectl describe pod output Correct answer
  • kubectl get nodes
  • kubectl version

Explanation: The scheduler reports why it couldn't place it in an event.

2 Create or update the objects in the file.

Question 
kubectl ____ -f api.yaml
Answer 
kubectl apply -f api.yaml

Explanation: apply is declarative.

3 Match.

Term Meaning
get List
describe Details
apply Apply
delete Delete

All lessons in Intermediate

1 What is Kubernetes?

  1. What is Kubernetes?
  2. Why Kubernetes?
  3. Cluster architecture
  4. Control plane
  5. Worker node
  6. Summary - What is Kubernetes

2 Minikube

  1. What is Minikube?
  2. Installing Minikube
  3. minikube start
  4. minikube status
  5. minikube dashboard
  6. Summary - Minikube

3 kubectl basics

  1. What is kubectl?
  2. kubectl get
  3. kubectl describe
  4. kubectl apply
  5. kubectl delete
  6. Summary - kubectl

4 Pod

  1. What is a Pod?
  2. Pod YAML
  3. Creating a Pod
  4. Pod status
  5. Multi-container Pod
  6. Summary - Pod

5 Deployment

  1. What is a Deployment?
  2. Deployment YAML
  3. Replica count
  4. Rolling update
  5. Rollback
  6. Summary - Deployment

6 ReplicaSet

  1. What is a ReplicaSet?
  2. ReplicaSet YAML
  3. ReplicaSet selector
  4. Scaling
  5. Self-healing
  6. Summary - ReplicaSet

7 Service

  1. What is a Service?
  2. ClusterIP
  3. NodePort
  4. LoadBalancer
  5. Service selector
  6. Summary - Service

8 ConfigMap

  1. What is a ConfigMap?
  2. ConfigMap YAML
  3. Environment variable
  4. Mounting as a volume
  5. kubectl create configmap
  6. Summary - ConfigMap

9 Secret

  1. What is a Secret?
  2. Secret types
  3. Secret YAML
  4. Mounting a Secret
  5. kubectl create secret
  6. Summary - Secret

10 Namespace

  1. What is a Namespace?
  2. kubectl get namespaces
  3. Creating a Namespace
  4. The -n flag
  5. Default Namespace
  6. Summary - Namespace

11 Labels and selectors

  1. What is a label?
  2. Adding labels
  3. Label selector
  4. kubectl get -l
  5. Equality and set selectors
  6. Summary - Labels

12 Project: Multi-tier app

  1. Project design
  2. Database Deployment
  3. Web Deployment
  4. ConfigMap and Secret
  5. Putting it together - multi-tier

13 Troubleshooting

  1. kubectl logs
  2. kubectl exec
  3. kubectl describe pod
  4. CrashLoopBackOff
  5. Pending Pod
  6. Summary - Troubleshooting

14 Intermediate final

  1. Challenge - Pod YAML
  2. Challenge - Deployment
  3. Challenge - Service
  4. Challenge - ConfigMap
  5. Challenge - Intermediate project