I'm trying to understand the difference between the manifest files used for bringing up the Kubernetes cluster.
Say suppose I have a file called pod.yml that defines my pod, that is the containers running it:
apiversion : v1
kind: Pod
metadata:
name : web
spec:
containers:
- name : webserver
image : httpd
ports :
- ContainerPort: 80
HostPort: 80`And I have replicator.yml file to launch 3 of these pods:
kind: "ReplicationController"
apiVersion: "v1"
metadata:
name: "webserver-controller"
spec:
replicas: 3
selector:
app: "webserver"
template:
spec:
containers:
- name: webserver
image: httpd
ports:
- containerPort: 80
hostport: 80`Can I avoid the template section in the replicator.yml if I'm already using pod.yml to define the images to be used to build the containers in the pod. Do you need all three manifest files pod.yml, service.yml and replicator.yml or can you just use service.yml and replicator.yml to create the cluster.
If you are using a ReplicationController, Deployment, DaemonSet or a Pet Set, you don't need a separate pod definition. However, the service should be defined if you want to expose the pod and this can be done on the same file.
Example:
apiVersion: v1
kind: Service
metadata:
name: default-http-backend
namespace: default
labels:
k8s-app: default-http-backend
spec:
ports:
- port: 80
targetPort: 8080
protocol: TCP
name: http
selector:
k8s-app: default-http-backend
---
apiVersion: v1
kind: ReplicationController
metadata:
name: default-http-backend
namespace: default
spec:
replicas: 1
selector:
k8s-app: default-http-backend
template:
metadata:
labels:
k8s-app: default-http-backend
spec:
terminationGracePeriodSeconds: 60
containers:
- name: default-http-backend
image: gcr.io/google_containers/defaultbackend:1.0
livenessProbe:
httpGet:
path: /healthz
port: 8080
scheme: HTTP
initialDelaySeconds: 30
timeoutSeconds: 5
ports:
- containerPort: 8080
resources:
limits:
cpu: 10m
memory: 20Mi
requests:
cpu: 10m
memory: 20Mi