Kubectl

Introduction to Kubectl

Kubectl is the Kubernetes cli version of a swiss army knife, and can do many things.

While this Book is focused on using Kubectl to declaratively manage Applications in Kubernetes, it also covers other Kubectl functions.

Command Families

Most Kubectl commands typically fall into one of a few categories:

Type Used For Description
Declarative Resource Management Deployment and Operations (e.g. GitOps) Declaratively manage Kubernetes Workloads using Resource Config
Imperative Resource Management Development Only Run commands to manage Kubernetes Workloads using Command Line arguments and flags
Printing Workload State Debugging Print information about Workloads
Interacting with Containers Debugging Exec, Attach, Cp, Logs
Cluster Management Cluster Ops Drain and Cordon Nodes

Declarative Application Management

The preferred approach for managing Resources is through declarative files called Resource Config used with the Kubectl Apply command. This command reads a local (or remote) file structure and modifies cluster state to reflect the declared intent.

Printing state about Workloads

Users will need to view Workload state.

  • Printing summarize state and information about Resources
  • Printing complete state and information about Resources
  • Printing specific fields from Resources
  • Query Resources matching labels

Debugging Workloads

Kubectl supports debugging by providing commands for:

  • Printing Container logs
  • Printing cluster events
  • Exec or attaching to a Container
  • Copying files from Containers in the cluster to a user’s filesystem

Cluster Management

On occasion, users may need to perform operations to the Nodes of cluster. Kubectl supports commands to drain Workloads from a Node so that it can be decommission or debugged.

Porcelain

Users may find using Resource Config overly verbose for Development and prefer to work with the cluster imperatively with a shell-like workflow. Kubectl offers porcelain commands for generating and modifying Resources.

  • Generating + creating Resources such as Deployments, StatefulSets, Services, ConfigMaps, etc
  • Setting fields on Resources
  • Editing (live) Resources in a text editor

Last modified September 23, 2020: docs update (b46eb865)