An image is basically an object that can be used to deploy an operating system to an OpenShift container, such as a Linux Red Hat operating system. These are typically small, lightweight operating systems that just contain the core features needed to run the operating system in an OpenShift container. Often, images come precompiled with certain features. For example, a Python image would contain the requirements needed to run a Python application in the container. A Node.js image would contain the requirements needed to run a Node.js application in the container.

A deployment includes a certain image and the deployment creates a replica set (which is the number of pods that should be created) and then the replica set should spawn pods, and each pod should include a container. The container runs the operating system.

The podman pull command can be used to pull an image from a registry. In this example, the hello-openshift image is pulled from registry.redhat.io.

AVOID TROUBLE

If "cannot clone: Invalid argument" is returned and you are not using sudo, try including sudo.

~]$ sudo podman pull registry.redhat.io/openshift4/ose-hello-openshift-rhel8:v4.7.0-202205312157.p0.g7706ed4.assembly.stream
Trying to pull registry.redhat.io/openshift4/ose-hello-openshift-rhel8:v4.7.0-202205312157.p0.g7706ed4.assembly.stream...
Getting image source signatures
Copying blob fd464176d200 done
Copying blob 818c647e4aa5 done
Copying blob cadc28304651 done
Copying blob bd80971c62b7 done
Copying blob f07762ea04d5 done
Copying config ec2022754d done
Writing manifest to image destination
Storing signatures
ec2022754d36012aa12de585ea09010057c28a1dc77035b3bd93e01fa81d5401