Pod Example

KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.

Multi Container Pod
========================
ideally, we always create a pod with single containers

Scenarios:

 > 2 tightly coupled container which are sharing some data

 > if you want 2 application to have same ip address

 > if you have scenario where 2 application have to run on same node always

 > In multi container pod we will never have container of same Image

 > in multi container pods, container share same network, so container with same port cannot run 


In k8s we always write a object definition file to create Pods

These files or manifests are written in Yaml

vim multicontainer-pod.yaml

# indicates the code schema that k8s will use to create a POD 
# every object is k8s will have its apiVersion defined
# you cannot change it.
# kind of object to be created. value is provided by k8s
# labels are mandatory for POD, they helps us to identify a group of pods in cluster

apiVersion: v1
kind: Pod 
metadata:
  name: multi-cont-pod2
  labels:
   author: sonal
   role: dev
spec:
  containers:
   - name: c1
     image: httpd
   - name: c2
     image: tomcat
   - name: c3
     image: ubuntu
     command: ["bash", "-c", "sleep 6000"]


kubectl create -f multicont-pod.yml
kubectl get pods
kubectl get pods -o wide

Steps to troubleshoot if the pods fails:

kubectl describe pod multi-cont-pod1 | less

kubectl logs multi-cont-pod1 -c c2

kubectl delete pods --all

kubectl explain pod | less