Kubernetes is an open-source container orchestration system for automating the deployment, scaling, and management of containerized applications. It was originally developed by Google and is now maintained by the Cloud Native Computing Foundation (CNCF).
One of the main advantages of using Kubernetes is its ability to abstract away the underlying infrastructure, allowing developers to focus on building and deploying their applications rather than worrying about the underlying hardware and software stack. Kubernetes provides a set of APIs and tools that can be used to deploy, scale, and manage containerized applications across a cluster of servers.
Kubernetes is built on top of the Docker container runtime and uses a declarative configuration model, which means that developers specify the desired state of their applications and Kubernetes takes care of ensuring that the application is running as intended. This makes it easy to deploy and manage applications, especially in large, complex environments where there may be multiple teams working on different parts of the application.
Kubernetes is also highly extensible, with a large ecosystem of tools and integrations available. This includes tools for monitoring, logging, load balancing, and more.
To get started with Kubernetes, you will need a cluster of servers and a way to deploy containerized applications to them. There are several ways to set up a Kubernetes cluster, including using cloud-based managed services such as Google Kubernetes Engine (GKE), Amazon Elastic Container Service for Kubernetes (EKS), or Azure Kubernetes Service (AKS), or you can set up your own cluster using tools such as kubeadm or minikube.
Once you have a cluster set up, you can deploy your applications using Kubernetes resources such as pods, services, and deployments.
KUBERNETES RESOURCES OR COMPONENTS
Kubernetes has a number of resources that are used to deploy and manage applications in a cluster. The most common resources include:
- Pods: A pod is the basic building block of a Kubernetes application and represents a single instance of a containerized application. Pods can contain one or more containers, and all containers in a pod share the same network namespace and storage. Pods are ephemeral and are not meant to be long-lived, so if a pod goes down, it will be replaced by a new one.
- Services: A service provides a way to expose pods to other parts of the cluster or to external clients. It acts as an abstraction layer over a set of pods and allows them to be accessed through a single stable endpoint, such as a DNS name or IP address. Services can be configured to load balance traffic to the pods they expose and can also be used to expose pods to the outside world through a load balancer.
- Deployments: A deployment is a higher-level resource that manages the rollout and rollback of a set of replicas of a pod. It ensures that a specified number of replicas of a pod are always running and can be used to update the pods in a rolling fashion, allowing for zero-downtime updates.
- ReplicaSets: A ReplicaSet is a lower-level resource that ensures a specified number of replicas of a pod are running at any given time. It is used by deployments to manage the replicas of a pod.
- StatefulSets: A StatefulSet is similar to a ReplicaSet, but is used to manage stateful applications that require persistent storage. It ensures that the pods are created and deleted in a specific order and provides a unique identity to each pod.
- DaemonSets: A DaemonSet is used to run a copy of a pod on every node in the cluster or a subset of nodes. It is often used for things like logging agents or monitoring agents that need to run on every node.
- Jobs: A Job is used to run a batch process to completion. It creates one or more pods and ensures that a specified number of them successfully complete.
- CronJobs: A CronJob is used to run a job on a schedule. It creates a Job at a specified time or interval.
These are some of the most common resources used in Kubernetes but there are many others available as well. It's important to understand the purpose and use case for each resource in order to effectively deploy and manage applications in a Kubernetes cluster. In later parts of this series, we would be learning about each resource in detail.
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