What should be inside a Pod in Kubernetes?

In a Pod in Kubernetes, there should be:

• One or more related containers that work as a single unit and share resources.
• Shared data storage (Volumes) for containers within the Pod.
• A common network stack for all containers (according to the IP specification).
• A Pod specification (PodSpec object) describing how containers should operate, including:
  • Container images.
  • Required resources (CPU, memory).
  • Ports that are open.
  • Environment variables.
  • Health probes (liveness and readiness probes).
  • Restart policies.

Typical usage:

• One main application container.
• One or more "sidecar" containers performing auxiliary tasks (logging, monitoring, adapters).

Example of a Pod specification (partial):

# Example of a partial Pod specification
apiVersion: v1
kind: Pod
metadata:
  name: my-app-pod
spec:
  containers:
  - name: main-app
    image: my-docker-repo/my-app:latest
    ports:
    - containerPort: 80
    resources:
      limits:
        cpu: "500m"
        memory: "512Mi"
  - name: log-collector
    image: my-docker-repo/log-collector:latest
    volumeMounts:
    - name: app-logs
      mountPath: /var/log/app
  volumes:
  - name: app-logs
    emptyDir: {}

Main principles:

• A Pod is the smallest deployable unit in Kubernetes.
• Containers within a Pod share the kernel namespace (PID, UTS, IPC).
• Scaling occurs at the Pod level.
• A Pod is intended for hosting tightly coupled processes.