KUBERNETES OVERVIEW FULL

Kube-proxy-enables the cluster to forward traffic to executing containers.

Kubelet-responsible for communicating to the master and ensuring the containers are running on the node.The worker nodes provide the container runtime for your applications and have a few components responsible for communicating with the master and networking on every worker node: etcd-an open-source distributed key value store used to hold the cluster data.Scheduler-responsible for scheduling compute requests on the cluster.Controller manager-responsible for watching the cluster’s objects and resources and ensuring the desired state is consistent.API server-exposes the Kubernetes API for controlling the cluster.The master (sometimes called the control plane) has three components and a data store: Kubernetes uses a master/slave communication model where there is at least one master and usually several worker nodes. It manages application configuration and secrets. Automated rollouts & rollbacks–During updates, the health of your new instances are monitored, and if a failure occurs, it can roll back to the previous version automatically.Service discovery & load balancing-IP address, DNS, and multiple instances are load-balanced.Volume management-It manages the persistent storage used by your applications.Horizontal scaling-By observing CPU or custom metrics, Kubernetes can add and remove instances as needed.Self-healing-If a container crashes, a new one will be created to replace it.Compute scheduling-It considers the resource needs of your containers, to find the right place to run them automatically.

With Kubernetes, you organize your applications in groups of containers, which it runs using the Docker engine, taking care of keeping your application running as you request. Kubernetes is an open-source container management platform that unifies a cluster of machines into a single pool of compute resources. If you want a hands-on example, this is a good great resource: Deploy Python using Docker containers. DockerHub is a well-known public registry, but there are also private registries like Azure Container Registry that allow you to keep your application images private. When you want to run a Docker image, you need to either build it or pull the image from a registry. Once you have an image, you push it to a container registry-a central repository for versioning your images. The docker builder takes this file and packages it into an image. To create an image with your application’s source code, you specify a list of commands in a special text file named Dockerfile. Docker containersĪ Docker image is a template a Docker container is a running instance of that template. Docker consists of a few components: a container runtime (called dockerd), a container image builder (BuildKit), and a CLI that is used to work with the builder, containers, and the engine (called docker). The underlying concept has been around longer than Docker’s technology, but it was not easy to do until Docker came out with its cohesive set of tools to accomplish it. What is Docker?ĭocker was first released in 2013 and is responsible for revolutionizing container technology by providing a toolset to easily create container images of applications.

If you want to learn more about containers, watch this short video on why you should care about containers. This removes the need to run a separate operating system for each application, allowing for higher resource utilization and lower costs. The container engine runs applications in containers isolating it from other applications running on the host machine.

KUBERNETES OVERVIEW FULL

This is because a VM runs not only your application but also a full operating system that needs resources too, so less would be available for your application to use.Ĭontainers solve this problem with two pieces: a container engine and a container image, which is a package of an application and its dependencies. The solution of one application per VM solved the isolation problem for conflicting dependencies, but it wasted a lot of resources (CPU and memory).

Before containers, if you had multiple applications deployed on the same virtual machine (VM), any changes to shared dependencies could cause strange things to happen-so the tendency was to have one application per virtual machine. What are containers?Ĭontainers effectively virtualize the host operating system (or kernel) and isolate an application’s dependencies from other containers running on the same machine. In this post, we’ll go through what they are and how you can learn more to advance to the next level. Understanding what problems containers, Docker, and Kubernetes solve is essential if you want to build modern cloud-native apps or if you want to modernize your existing legacy applications. Modern application infrastructure is being transformed by containers.

Kubernetes overview