Kubernetes Architecture Overview
Introduction
Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.
Understanding its architecture is crucial for effectively using Kubernetes.
Key Components
The architecture of Kubernetes consists of a control plane and the nodes that run your applications.
- Control Plane
- Node Components
- Networking
- Storage
Control Plane
The control plane manages the Kubernetes cluster. It is responsible for the global state of the cluster and is composed of the following components:
- API Server: The front-end of the Kubernetes control plane that handles requests.
- Etcd: A distributed key-value store that holds the cluster state.
- Controller Manager: Manages controller processes that regulate the state of the cluster.
- Scheduler: Assigns workloads to nodes based on resource availability.
Node Components
Each node in a Kubernetes cluster runs the following components:
- Kubelet: An agent that runs on each node, ensuring containers are running in a pod.
- Kube Proxy: Maintains network rules for pod communication.
- Container Runtime: Software responsible for running containers (e.g., Docker, containerd).
Networking
Kubernetes networking allows communication between pods, services, and external applications. Key concepts include:
- ClusterIP: The default service type that exposes services on a cluster-internal IP.
- NodePort: Exposes a service on a static port on each node's IP.
- LoadBalancer: Creates an external load balancer.
Storage
Kubernetes supports different types of storage:
- Persistent Volumes (PV): A piece of storage in the cluster.
- Persistent Volume Claims (PVC): A request for storage by a user.
- Storage Classes: Define types of storage offered in the cluster.
Best Practices
Here are some best practices for working with Kubernetes:
- Use namespaces to organize resources.
- Implement RBAC for security.
- Monitor resources and set limits.
- Regularly back up etcd.
FAQ
What is the purpose of the API server?
The API server is the central management entity that receives all requests and updates for the Kubernetes cluster.
What is etcd?
etcd is a distributed, reliable key-value store that is used to hold and manage the critical data of the Kubernetes cluster.
How does Kubernetes handle scaling?
Kubernetes can scale applications up or down automatically based on resource usage through Horizontal Pod Autoscaler.