Kubernetes Container Image Pull Concepts
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External
- https://kubernetes.io/docs/concepts/containers/images/
- https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/
Internal
Overview
A pod's containers pull their images from their respective repositories while the pod is in Pending phase. Technically, it is the kubelet that performs the image pulling on behalf of the pod.
Pull Policy
The pull policy is configured on a per-container basis using the imagePullPolicy tag in the pod manifest.
There are three possible values: Always
, IfNotPresent
and Never
. This attribute is optional, and if it is not specified, it is inferred based on the image tag. The default is Always
if ":latest" tag is specified, or IfNotPresent
otherwise.