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k8s Cheat Sheet

This all-in-one k8s cheat sheet can be used for quick reference.

k8s Resource Types

Here are the primary k8s resource types we have covered in this class:

  • Pods -- Pods are the simplest unit of compute in k8s and represent a generalization of the Docker container. Pods can contain more than one container, and every container within a pod is scheduled together, on the same machine, with a single IP address and shared file system. Pod definitions include a name, a (Docker) image, a command to run, as well as an ImagePullPolicy, volumeMounts and a set of ports to expose. Pods can be thought of as disposable and temporary.
  • Deployments -- Deployments are the k8s resource type to use for deploying long-running application components, such as APIs, databases, and long-running worker programs. Deployments are made up of one or more matching pods, and the matching is done using labels and labelSelectors.
  • PersistentVolumeClaims (PVCs) -- PVCs create a named storage request against a storage class available on the k8s cluster. PVCs are used to fill volumes with permenant storage so that data can be saved across different pod executions for the same stateful application (e.g., a database).
  • Services -- Services are used to expose an entire application component to other pods. Services get their own IP address which persists beyond the life of the individual pods making up the application.

kubectl Commands

Here we collect some of the most commonly used kubectl commands for quick reference.

Command Description Example
kubectl get <resource_type> List all objects of a given resource type. kubectl get pods
kubectl get <type> <name> Get one object of a given type by name. kubectl get pods hello-pod
kubectl get <type> <name> -o wide Show additional details of an object kubectl get pods hello-pod -o wide
kubectl describe <type> <name> Get full details of an object by name. kubectl describe pods hello-pod
kubectl logs <name> Get the logs of a running pod by name. kubectl logs hello-pod
kubectl logs -f <name> Tail the logs of a running pod by name. kubectl logs -f hello-pod
kubectl logs --since <time> <name> Get the logs of a running pod since a given time. kubectl logs --since 1m -f hello-pod
kubectl exec -it <name> -- <cmd> Run a command, <cmd>, in a running pod. kubectl exec -it hello-pod -- /bin/bash
kubectl apply -f <file> Create or update an object description using a file. kubectl apply -f hello-pod.yml