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Kubernetes Pod lifecycle events

The lifecycle of a Kubernetes Pod is managed by the kubelet and involves several distinct states and transitions.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]

Pod States

A Pod's status field represents a specific phase in its lifecycle, typically progressing through creation, scheduling, and eventual running states.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]

The following are the common lifecycle states observed in a Pod's existence:

  • Scheduled: The event indicating the system has successfully assigned the Pod to a specific Node in the cluster.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • Pulling: The state where the kubelet is actively downloading the container image from the registry.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • Pulled: The event logged after the container image has been successfully retrieved.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • Created: The state indicating the container has been created (e.g., empty filesystem created) but not yet started.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • Running: The state indicating the container is actively executing.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]

Pod Conditions

To provide a more granular view of Pod status, Kubernetes manages specific boolean conditions that reflect the health and readiness of the Pod.^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]

A healthy Pod typically exhibits the following condition values:

  • PodScheduled: True (The Pod has been scheduled to a node).^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • Initialized: True (All Init containers have started successfully).^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • ContainersReady: True (All containers in the Pod are ready).^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]
  • Ready: True (The Pod is able to serve requests and is included in service load balancers).^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]

Sources

^[400-devops__06-Kubernetes__k8s-learning__03.pod__README.md]