Kubernetes Cheatsheet

Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available. Kubernetes provides you with a framework to run distributed systems resiliently. It takes care of scaling and failover for your application, provides deployment patterns, canary deployments, and more. In this blog post, I will mention Kubernetes commands which we need for most of the use-cases.

I will list down kubectl commands in the sections below as a quick reference to work with Kubernetes.

List Resources
Create Resources
Update Resources
Display the State of Resources
Delete Resources
Execute Command
Print Container Logs
Modify Kubeconfig Files

List Resources

Get list of all namespaces
```
kubectl get namespaces
```
Get list of all pods
```
kubectl get pods
```
Get list of all pods with detailed information like IP, Node Name etc...
```
kubectl get pods -o wide
```

Get list of all pods running on a particular node server

kubectl get pods --field-selector=spec.nodeName=[server-name]

Get list of all replication controllers and services
```
kubectl get replicationcontroller,services
```
Get list of daemonsets
```
kubectl get daemonset
```

Create Resources

Create a new namespace

kubectl create namespace [namespace-name]

Create a new namespace from JSON or YAML file.
```
kubectl create –f [filename]
```

Update Resources

To apply or update a resource use the kubectl apply command.

Create a new service with the definition contained in [service-config].yaml
```
kubectl apply -f [service-config].yaml
```
Create a new replication controller with the definition contained in [controller-config].yaml
```
kubectl apply -f [controller-config].yaml
```
Create the objects defined in any .yaml, .yml, or .json file in a directory
```
kubectl apply -f [yaml-file/directory-name]
```
Edit a service config
```
kubectl edit svc/[service-name]
```
Above command opens the file in your default editor. To choose another editor, specify it in front of the command:
```
KUBE_EDITOR=”[editor-name]” kubectl edit svc/[service-name]
```

Display the State of Resources

Get Details about Particular Node
```
kubectl describe nodes [node-name]
```
Get Details about a Particular pod
```
kubectl describe pods [pod-name]
```
Get Details about a Particular pod whose name and type are listed in pod.json
```
kubectl describe –f pod.json
```
Get Details about a Particular pod managed by a specific replication controller
```
kubectl describe pods [replication-controller-name]
```
Get Details about all pods
```
kubectl describe pods
```

Delete Resources

Delete a pod using the name and type mentioned in pod.yaml
```
kubectl delete -f pod.yaml
```

Delete all pods and services with a specific label

kubectl delete pods,services -l [label-key]=[label-value]

Delete all pods
```
kubectl delete pods --all
```

Execute Command

Get output from a command run on the first container in a pod
```
kubectl exec [pod-name] -- [command]
```
Get output from a command run on a specific container in a pod
```
kubectl exec [pod-name] -c [container-name] -- [command]
```
Run /bin/bash from a specific pod. The received output comes from the first container
```
kubectl exec -ti [pod-name] -- /bin/bash
```

Print Container Logs

Print Logs from Pod
```
kubectl logs [pod-name]
```
Stream Logs from Pod
```
kubectl logs -f [pod-name]
```
Tail Logs from Pod (Print last 200 logs from pod)
```
kubectl logs --tail=200 [pod-name]
```

Modify Kubeconfig Files

kubectl config command lets you view and modify kubeconfig files.

Get Current Context
```
kubectl config current-context
```

Set cluster entry in kubeconfig

kubectl config set-cluster [cluster-name] --server=[server-name]

Unset an entry in kubeconfig
```
kubectl config unset [property-name]
```

Thank you for reading

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