In Kubernetes, the scheduler assigns pods to nodes in an ordered fashion, ensuring that pod requirements and node resources are properly matched. Here's a step-by-step overview of the pod scheduling process:
- Creation of a Pod?A pod is created in 'Pending' state when you submit a configuration file or define a pod using a controller (Deployment, ReplicaSet, etc.).
- Observation of Unscheduled Pod?The Kubernetes scheduler watches for pods with no assigned nodes and selects a pod for scheduling.
- Node Filtering?Nodes that do not meet the pod's requirements are filtered out, considering factors such as resource availability, taints and tolerations, affinity rules, and pod constraints.
- Node Scoring?The scheduler assigns a score to each remaining node based on factors like resource utilization, affinity rules, data locality, and node topology.
- Binding Pod to Node?The pod is bound to the highest-scoring node, with the necessary details added to the pod's object status.
- Kubelet Sync?The kubelet daemon running on the assigned node syncs with the API server and receives information about the pod to be deployed.
- Pod Instantiation?The kubelet instantiates the pod on the assigned node, creating the appropriate containers and managing their lifecycle.
- Pod Running State?Once the pod is running on the node, the kubelet continuously communicates with the API server to update the pod's status.
Understanding the ordered process of pod scheduling in Kubernetes enhances your ability to plan and manage resources effectively in cloud-native environments. Stay tuned for more DevOps Tips & Tricks!
