ReplicaSet

A. replication Controller

• replicationController is a older way
• ReplicaSet is a new way, with some diff.
• makes sure specified number of pods running all the time.
• span across node/s
• 
• yml (spec)
• replicas : 3
• nest the pod file in template section
• it manages only pod defined in template
• 
• 

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B. Replica Set

• concept and yml --> almost same.
• it also manages pods, not defined in template section.
• thus having spec.selector (mandatory)

...
...
spec:
    ...
    ...
    selector: 
        matchLabels:
            type: front-end

## Some commands:
- kubectl get replicaset
- kubectl create -f <yaml>
- kubectl scale --replicas=6 -f replicaSet-definition.yaml
- kubectl scale --replicas=6 replicaset replicaset-1
- kubectl delete replicaset rs-1
    - all linked pods will be deleted.
-  kubectl get replicaset -o yaml > sample.yaml

Note: use rs

label and selector

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