KodeCloud Kubernetes Pods
Links: 111 KodeCloud Index
- Nodes were also known as minions in the past.
- Scheduler - Placement. Where to put containers in a node.
- Controller - Brain. Responds when something goes down.
- Get k8s version:
k version --short
kubeadmis used to bootstrap and manage production grade k8s cluster.
- Pod is the smallest component you can create in k8s.
Multiple containers in a pod can communicate with each other directly by referring to each other as localhost since they share the same network space.
They can also easily share the same storage space.
- Creating and running a pod:
k run <pod-name> --image=<image>
- Describing things:
k describe <resource-type>/<resource-name>
k describe pod/<pod-name> can give a lot of additional information about the pod
- Node to which it belongs,
- Image name
- Events that occurred in the pod.
- We can see the different containers that are present in the pod and their states.
- Pod IP
- Any configuration file must have these properties:
There is a subtle difference between
kubectl create and
kubectl apply commands.
kubectl create command creates a new resource. So, if the command is run again it will throw an error as resource names should be unique in a namespace.
kubectl apply command applies the configuration to a resource. If the resource is not there then it will be created.
kubectl apply command can be run the second time even if the configuration hasn't changed.
- In the
kubectl create, we specify a certain action, in this case
create and so it is imperative. In the
kubectl apply command we specify the target state of the system and don't specify a certain action and so declarative. We let the system decide what action to take. If the resource is not there it will create it, if the resource is there then it will apply the configuration to the existing resource.
- From an execution perspective, there is no difference when a resource is created for the first time between
kubectl create and
- Creating a pod using a YAML file
Use only spaces and NOT TABS.
Last updated: 2022-10-10