Kubernetes uses YAML files as the input for objects - pods, replics, deployments, services etc.
A Kubernetes Definition File always contains 4 top level fields:
apiVersion - version of the Kubernetes API used to create the object. An example is v1. Others are listed below:
kind - type of object we are trying to create. An example is Pod Other possible values are ReplicaSet, Deployment or Service
metadata - data about the object - name, labels, app. The values shown are in the form of a dictionary. Everything is indented to the right, so for example name and labels are children of metadata. The number of spaces between the two properties does not matter. You cannot have more indents for labels for example, as it then becomes a child of the name property. The two properties also need more spaces ahead of their parent metadata. name is a string value. labels is a dictionary within the metadata dictionary. It can have any key / value pairs as required. The labels help you identify the object at a later point in time. Cannot add any old property under metadata.
spec - specifies the container / image needed in the pod. Provides additional information to Kubernetes, regarding the object. Refer to the documentation to understand the right format for each. spec is a dictionary. We add a property under it called containers. containers is a list / array. This is due to pods having multiple containers within them. A - before the word name: indicates the first item in the list. name and image are dictionary properties. In this case, image is nginx, which is the name of the image in the Docker repository.
Required fields and they must be in the configuration file.
Once the YAML file is created, we run kubectl create -f pod-definition.yml
Kubernetes then creates the pod.
See the pods with kubectl get pods
To see detailed information about the pod, run kubectl describe pod <pod_here>
