kubectl Usage Conventions

Recommended usage conventions for kubectl.

Using kubectl in Reusable Scripts

For a stable output in a script:

• Request one of the machine-oriented output forms, such as -o name, -o json, -o yaml, -o go-template, or -o jsonpath.
• Fully-qualify the version. For example, jobs.v1.batch/myjob. This will ensure that kubectl does not use its default version that can change over time.
• Don’t rely on context, preferences, or other implicit states.

Best Practices

kubectl run

For kubectl run to satisfy infrastructure as code:

• Tag the image with a version-specific tag and don’t move that tag to a new version. For example, use :v1234, v1.2.3, r03062016-1-4, rather than :latest (For more information, see Best Practices for Configuration).
• Check in the script for an image that is heavily parameterized.
• Switch to configuration files checked into source control for features that are needed, but not expressible via kubectl run flags.

You can use the --dry-run=client flag to preview the object that would be sent to your cluster, without really submitting it.

Note: All kubectl run generators are deprecated. See the Kubernetes v1.17 documentation for a list of generators and how they were used.

Generators

You can generate the following resources with a kubectl command, kubectl create --dry-run=client -o yaml:

  clusterrole         Create a ClusterRole.
  clusterrolebinding  Create a ClusterRoleBinding for a particular ClusterRole.
  configmap           Create a configmap from a local file, directory or literal value.
  cronjob             Create a cronjob with the specified name.
  deployment          Create a deployment with the specified name.
  job                 Create a job with the specified name.
  namespace           Create a namespace with the specified name.
  poddisruptionbudget Create a pod disruption budget with the specified name.
  priorityclass       Create a priorityclass with the specified name.
  quota               Create a quota with the specified name.
  role                Create a role with single rule.
  rolebinding         Create a RoleBinding for a particular Role or ClusterRole.
  secret              Create a secret using specified subcommand.
  service             Create a service using specified subcommand.
  serviceaccount      Create a service account with the specified name.

kubectl apply

• You can use kubectl apply to create or update resources. For more information about using kubectl apply to update resources, see Kubectl Book.