Based on what property does the replica find the pods to manage?

A Replica finds the pods it needs to manage through the selector property.

This property in the ReplicaSet (or Deployment, which manages the ReplicaSet) specification defines a set of labels (key: value) that a pod must have for the ReplicaSet to consider it "its own" and manage its lifecycle.

For example:

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: my-app-rs
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-container
        image: nginx:latest

In this example, selector.matchLabels is set to app: my-app. The ReplicaSet will look for pods with the label app and value my-app and manage their number, maintaining the desired number of replicas (in this case - 3).

It is important that the labels specified in selector match the labels assigned to the pods in the template.metadata.labels field. This ensures the correct binding of the ReplicaSet to the pods it should control.