Developers have been using various ways to create and deploy applications. The most common are the traditional methods of deployment. Since this is the era of new technology advancements, software companies have been continuously introducing and applying the latest application deployment platforms to improve the process. Docker is the most common platform that has gained massive popularity relatively quickly by switching the deployment methods to isolated containers. Kubernetes is another platform that provides container-based deployment.
Kubernetes, usually known by the name k8s traces back its roots to its initial release about six years ago in 2014. It is an open-source system, which means they have kept the doors open for improvement by collaborating with any individual or organization. Kubernetes works on container orchestration systems. Working on these systems means that the Kubernetes platform can arrange units or environments to produce the desired outcome in the form of a better-deployed computer application.
Google originally developed Kubernetes in 2014. However, the developers of the Cloud Native Computing Foundation (CNCF) maintain this platform now. CNCF is a well-known organization registered under the Linux Foundation to maintain and use container technology in sustainable ecosystems. Kubernetes is a cluster management software that promises to provide a stable platform for automatically deploying applications. This platform ensures automated deployment, mounting, and smoothly operating application containers on various clusters of hosts.
Kubernetes consists of the following essential features:
Kubernetes works on clustered architecture. It works on architecture, which is client and server-based. It has a master installed on a separate machine and has a node installed on a particular machine. Master and node are the servers that exist at the highest level of the Kubernetes. These servers can be of different kinds, such as physical machines, Virtual Machines (VMs), and Linode.
It is a server that controls the cluster state. It bears the responsibility to maintain the user desired state of the clusters. It works by communicating with the node and telling it the number of instances of the user’s applications that the node should run and their locations.
It is a server that runs the user applications and is also known as a worker server. In most cases, there is more than one node server. However, the decisions about the server count wholly depend on the users’ choice and the workload. Additionally, the nodes run the Kubelet and the Kube proxy server processes, which are explained below.
Both Master and Node work on different Linux platforms having the following essential components:
As there can be more than one container deployed to a single node, that group of containers in each node is called a pod. The containers in a single pod have the same hostname, IP address, IPC, and other required resources. Furthermore, the pods make it easier to move containers in the cluster because of the abstract strength and network.
This component stores the valuable information which every node in the cluster can utilize. It stores the information in a key-value pair and then distributes the store to all nodes. Additionally, Kubernetes API can access it.
An API server implements an interface for the easy usability of tools and libraries. The users utilize the Kubeconfig package with tools for communication.
This component manages the controllers which are responsible for the state of clusters. It sends and collects information from the API server. Some of the vital controllers are the replication controller, endpoint controller, namespace controller, and service account, controller.
This component distributes the workload and keeps track of workload utilization on cluster nodes. Moreover, it allocates pods to new nodes using methods of efficient resource allocation.
Docker helps in running encapsulated application containers in an isolated operating environment.
It receives and sends information to the control panel service. It reads configuration information from etcd. It receives commands from the master and manages network rules and port forwarding.
This proxy service runs on each node separately and makes other services available for the external host. It forwards valid container requests and helps in balancing the load. This component helps manage pods on nodes, volumes, secrets, creating new containers’ health checkups, and much more.
It is a command-line tool that users use for controlling and interacting with the clusters. This tool offers a variety of services, such as create, delete, and stop resources. Moreover, its features also include auto-scale resources and describe active resources as well.
As mentioned above, Kubernetes is a professionally organized tool that works with creating, managing, and deploying containerized applications. It also has some responsibilities considering the change it promised to bring in the traditional development environments:
It has to bear the responsibility to deploy images and containers. Moreover, developers use it to deploy containerized applications on clusters.
It is also responsible for the scaling and management of specified various containers and clusters. It scales the deployment of applications and managing in the future when a new version of the software of a containerized application is released.
It ensures a balanced allocation of resources by efficiently working on distributing resources to containers and clusters.
Moreover, it allows the debugging of containerized applications. Also, it provides solutions for managing traffic for the services offered by it.
Kubernetes proves to be helpful when it comes to the deployment of applications. It scales and manages containerized applications. It has become popular among developers and DevOps teams. Using Kubernetes can help us provide with the following benefits:
It can work with Docker containers and help to work with cloud applications and microservices. It also works well with continuous integration and continuous deployment tools to provide a better user experience while working. Moreover, it is also famous for developing applications for cloud and hyper-cloud environments.
The vast ecosystem of Kubernetes improves productivity massively. It uses specified tools for cloud-native software to work with applications efficiently.
Kubernetes was ranked as the 3rd most wanted developing platform in the 2019 survey on stack overflow developers. Moreover, it can provide a massive benefit to potential learners by introducing them to cloud-native technology and keeping them ahead of their competitors in the market.
Kubernetes is growing popular among developers and users of various virtual environments because it provides them with better and faster deployment of the applications. Moreover, this provides an open-source platform that is also production-ready to avoid unnecessary delays. All in all, Kubernetes is a platform that enables the users to schedule and run their clusters of physical, virtual machines, clouds, or any medium of the user’s choice.
kubectl is the Kubernetes command-line tool which, allows users to run commands against Kubernetes clusters. The user uses kubectl to deploy applications, inspect and accomplish cluster resources.
kind allows users to run Kubernetes on the local host machine. It requires Docker installed and configured on the local machine.
Minikube is a tool that lets users use Kubernetes locally. Minikube runs a single-node Kubernetes cluster on the localhost (Windows, macOS, and Linux PCs) to help users try out Kubernetes or daily development tasks.
Users may use the kubeadm tool to develop and manage Kubernetes clusters. It performs the necessary actions to get a minimum practical, secure cluster up and functional in a user-friendly environment.
Users must use a kubectl version which, is within one minor version difference of the cluster. For example, a v1.3 client should work with v1.2, v1.3. The up-to-date version of kubectl helps avoid unforeseen issues in development.
Kubectl is simply implementable on windows using the curl library.
curl -LO https://dl.k8s.io/release/v1.20.0/bin/windows/amd64/kubectl.exe
CertUtil -hashfile kubectl.exe SHA256 type kubectl.exe.sha256
Download & Install the checksum file using CMD and CertUtil Library.
Add the binary in user PATH and validate the installed version.
kubectl version --client
Docker Desktop for Windows adds its version of kubectl to PATH. Suppose the user has installed Docker Desktop before. In that case, the user may need to place the PATH registry before the one added by the Docker Desktop installer or remove the Docker Desktop’s kubect.
Once the user has the Kubernetes cluster, it may deploy the containerized applications on it. To make things happen, the user may create a Kubernetes configuration. The deployment instructs Kubernetes on how to generate and update instances of the application. Once it is in Deployment state, the Kubernetes master schedules the instances included in that deployment to run on singular Nodes in the cluster.
Once the application instances are configured, a Kubernetes Deployment Controller uninterruptedly monitors those instances. If the node hosting an instance goes down, the Deployment controller replaces the instance on another Node in the cluster. It provides a self-healing mechanism to address machine failure or maintenance.
Installation scripts help to start the applications, but they do not allow recovery from machine failure. By both creating your application instances and keeping them running across all the nodes, Kubernetes Deployments provides a fundamentally dissimilar approach to application management.
Users may create and manage the deployment by using the Kubernetes command-line interface (CMD), Kubectl. It uses the Kubernetes API to cooperate with the cluster.
When a user creates a Deployment, it needs to specify the container image for the application and the number of duplications that a user wants to run. It may change that information later by updating the deployment.
Applications must package into one of the supported formats to get deployed on Kubernetes
For the first Deployment, the User uses a hello-node application packaged in a Docker container that uses NGINX to print all the requests.
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