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Linux containers are a technology that allows you to run multiple isolated applications on a single host operating system. They are lightweight, portable, and efficient, making them ideal for deploying applications in various environments such as development, testing, and production. In this article, we will introduce two popular tools for managing Linux containers: Docker and Kubernetes.
Docker
Docker is a software platform that enables you to build, run, and share containerized applications. Docker uses a client-server architecture, where the Docker daemon runs on the host machine and communicates with the Docker client, which is a command-line tool or a graphical user interface. Docker provides a standard way to package an application and its dependencies into a single image file, which can be stored in a registry and pulled by any Docker host. Docker also provides a way to define how a container should run, such as its network settings, volumes, environment variables, and commands. Docker uses a layered filesystem to optimize the storage and transfer of images, and supports various isolation features such as namespaces, cgroups, and seccomp.
Kubernetes
Kubernetes is an open-source system for automating the deployment, scaling, and management of containerized applications. Kubernetes is based on the concept of pods, which are the smallest units of deployment in Kubernetes. A pod consists of one or more containers that share the same network and storage resources. Pods can be deployed on nodes, which are physical or virtual machines that run the Kubernetes agent called kubelet. Kubernetes also provides various abstractions and controllers to manage the state and behavior of pods, such as services, deployments, replicasets, daemonsets, jobs, cronjobs, and more. Kubernetes uses an API server to expose its functionality and communicate with other components such as etcd (a distributed key-value store), scheduler (which assigns pods to nodes), controller manager (which runs various controllers), and kube-proxy (which handles network routing).
Summary
Docker and Kubernetes are complementary technologies that can work together to provide a powerful platform for developing and running containerized applications. Docker simplifies the creation and distribution of images, while Kubernetes simplifies the orchestration and scaling of pods. Together, they enable you to build applications that are portable, scalable, resilient, and easy to update. In this article, we have given a brief overview of Linux containers, Docker, and Kubernetes. To learn more about these topics, you can visit their official websites or check out some of the online courses and tutorials available.