Kubernetes Manifests

Internal

• API Resources Concepts

Overview

A manifest expresses the desired state of a specific component of the application, and it is POSTed to the API server to instruct the cluster to adjust the corresponding current state. The steps involved by processing a manifest are described here:

Declarative versus Imperative Approach

Manifest files can be generated with kubectl kustomize.

TODO

Commonality. There are common elements with the same semantics for all manifests (e.g. metadata.name). Address them here in a common section, and link from individual "kinds" to here.

Common Elements

apiVersion

The apiVersion field contains the API group and the API version of the resource's specification. Normally, the format is:

apiVersion: <group>/<version>

However, some of the most common resources are defined in a special API group called the core group. For those resources, we can omit the <group> part when specifying apiVersion. While a StorageClass object should be specified as apiVersion: storage.k8s.io/v1, a pod, whose corresponding type is defined in the core group, should be specified as apiVersion: v1.

There are situations when an object is declared with an apiVersion, but after deployment, when the object is introspected, the return values shows a different version. For example, the object may be deployed as apiVersion: v1, but introspection after deployment may show apiVersion: v1beta1. This is normal behavior.

kind

The .kind field

metadata

Manifest Metadata

Manifest Operations

• POSTing a Manifest
• Get the Manifest for an Existing Object