L
Luke
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What is Kubernetes?
Kubernetes (or K8s) is an open-source developed by Google for container management. It can deploy on vary platform (On-premise, Cloud, Virtual Machine). Many large companies use it for system deployment and management.
Why is Kubernetes?
We have several popular ways to deploy application
- Traditional
- Virtualized
- Container
Each approach has its advantages and disadvantages. Here, I will focus on the third approach (Container), which is more popular than the others. For a simple term, think of your server as a ship, and each container it carries is an isolated application ready to be deployed. Sound great, but we have another problem:
- How we manage it?
- How we scale it?
- What happen if the "ship" drown?
When we're anxious to find a solution, Google offers helpful solution - Kubernetes
How Kubernetes work?
Kubernetes enables application grouping and management via namespaces, and its Services facilitate traffic routing to the correct applications. When a "ship" drown, it move our container to another "ship" to ensure high availability for the app. And many, many things we can work on it. And here is the "secret" behind it - architecture
Control plane (Master node)
It responsible for application management and high availability (HA). We never run application on it.
API Server
- Kubernetes's heart
- All components must communicate through it, not directly.
Control manager
- It contain vary controller for each purpose (deployment, services, storage, etc.)
Cloud control manager
- Only appear on cloud platform
Scheduler
- Resource coordinator
etcd
- A database stores the cluster's state, including configurations, node data, pod data, and service data.
P/s: Backing up etcd is crucial for Kubernetes availability.
Node (Worker node)
The application will run inside this; the number of worker nodes is limited only by your budget.
And worker node have 3 mains components:
Container Runtime Interface (CRI)
- Run container (docker, containerd or something else)
- A CRI contains one or more pods, each representing an application
Kubelet
- Receive and execute from API Server
- Transmit system information to API server
- Ensure containers/pods run correct state
- Continuously report pod/node status to the control plane and manage the pod lifecycle on the node
Kubernetes Service Proxy
- Maintain network rules for pod connectivity within and outside the cluster
Conclusion
We have go through the Kubernetes architecture and know what is it. In the next post, I will guide you install and run Kubernetes with on-premise system.
Happy Coding!
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