Kubernetes in 10 Minutes: A Complete Guide
Kubernetes in 10 Minutes: A Complete Guide
What's all the hype about Kubernetes? Find out why enterprises love this platform through a review of some of its most helpful features.
Join the DZone community and get the full member experience.Join For Free
Unleashing the power of Kubernetes to simplify workloads by deploying cloud- applications anywhere and managing from everywhere.
Kubernetes: What, Why, How, and When
As containers have gained in popularity over the past few years, Kubernetes consulting is redefining the way software is developed, deployed, and maintained. Most of the articles on the internet declare that Kubernetes is taking container orchestration by storm. We were wondering about its usage, so we searched on the web for surveys and concluded Kubernetes indeed is the highest-used container orchestration tool.
If the stats of the previous three years are to be believed, it can be rightly and undoubtedly said that Kubernetes is the most widely used container management platform. It has been dominating the container space for a couple of years.
Here the question arises: Why? What? When? How?
We will explain you everything.
This article is not for only technical leaders but it is also for a non-technical founder who is looking to develop the complex application by enhancing efficiency and simplifying the workload.
So, let’s start.
Before Kubernetes: How Kubernetes Came Into the Existence
The Gist of Containers
Before, containers were the best concept to deploy applications. It gave a new horizon for developing and maintaining software. With containers, it was easy for the software developers to package up an application including the components like libraries and other dependencies. It can ship a package as a whole without the need of a traditional virtual machine.
When the computing world became distributed, more network-based, and more reliant on cloud computing, monolithic apps migrated to microservices. These microservices enabled users to individually scale key functions and have the ability to handle millions of customers. On the top of that, tools like Docker Container, Mesos, and AWS ECS emerged into the enterprise, creating a consistent, portable, and easy way for the users to deploy microservices.
But, once the application gets matured and complex, there will be a need to run multiple containers across multiple machines. You need to figure out which is the right containers and at a right time of course, how they can communicate with each other, tackle with the large storage need, and deal with a failed container. Doing all this manually can be a nightmare!
Hence, to solve the orchestration needs of the containerized application, Kubernetes came to be.
Kubernetes History: A Quick Overview
When Docker continued to thrive managing microservices and containers, a container management system became a paramount requirement. During that time, Google was already running a container-based management infrastructure for many years and in that era, the company made a bold decision to open source an in-house project called Borg. Borg was a key to running Google’s services like Gmail and Google Search. To enhance the functionalities of the container management system, the company came up with Kubernetes – an open source project that automates the process of deploying and managing multi-container applications at scale. Kubernetes came into existence in mid-2014 and in a short span of time grown as open source community with engineers from Google, Red Hat, and many other companies contributing to the project.
What is Kubernetes?
Kubernetes is an open source container management system which is used in large-scale enterprises in several vertical industries to perform a mission-critical task. Some of its capabilities include:
Managing clusters of containers
Providing tools for deploying applications
Scaling applications as and when needed
Managing changes to the existing containerized applications
Helping to optimize the use of underlying hardware beneath your container
Enableing the application component to restart and move across the system as and when needed
Kubernetes provides much more beyond the basic framework, enabling users to choose the type of application frameworks, languages, monitoring and logging tools, and other tools of their choice. Although it is not Platform as a Service, it can be used as a basis for a complete PaaS.
In a few years, it has become a highly popular tool and one of the biggest success stories on the open-source platform.
Kubernetes Architecture: How It Works
Kubernetes’s Master-Slave Architecture and its components:
It is the primary control unit that manages workloads and communication across the system. Each of its components has a different process which can run on a single master node or on multiple master nodes. Its components are:
Etcd Storage: It is an open-source key-value data store developed by CoreOS team and can be accessed by all nodes in the cluster. Kubernetes uses "Etcd" to store configuration data of the cluster to represent the overall state of the cluster anytime.
API-Server: The API server is the central management entity that receives REST requests for modifications, serving as a front-end to control cluster. Moreover, this is the only thing that communicates with Etcd cluster, making sure that data is stored in Etcd.
Scheduler: It helps to schedule the pods on various nodes based on resource utilization and decides where to deploy which service. The scheduler has the information regarding the resources available to the members as well as the one which is left for configuring the service to run.
Controller Manager: It runs a number of distinct controller processes in the background to regulate the shared state of the cluster and perform a routine task. When there is any change in the service, the controller spots the change and starts working towards the new desired state.
This is also known as a Kubernetes or Minion node, and it contains the information to manage networking between containers such as Docker and communication between the master node as assigning the resources to the containers as per schedule
Kubelet: Kubelet ensures that all containers in the node are running and are in a healthy state. Kubelet monitors the state of a pod if it is not in the desired state. If a node fails, a replication controller observes this change and launches pods on another healthy pod.
Container: Containers are the lowest level of microservice, placed inside the pod and needs external IP address to view the outside process.
Kube Proxy: It acts as a network proxy and a load balancer. Additionally, it forwards the request to the correct pods across isolated networks in a cluster.
cAdvisor: Acts as an assistant who is responsible for monitoring and gathering data about resource usage and performance metrics on each node.
Advantages of Kubernetes
Portable and Open-Source
Kubernetes can run containers on one or more public cloud environment, virtual machine, or on bare metal which means it can be deployed on any infrastructure. Moreover, it is compatible across several platforms, making multi-cloud strategy highly flexible and usable as well.
Kubernetes offers several useful features for scaling purpose:
Horizontal Infrastructure Scaling: Operations are done at the individual server level to implement horizontal scaling. New servers can be added or removed easily.
Auto-Scaling: Based on the usage of CPU resources or other application-metrics, you can modify the number of containers that are running.
Manual Scaling: You can manually scale the number of running containers through a command or the interface.
Replication Controller: The replication controller makes sure that cluster has a specified number of equivalent pods in a running condition. If there are too many pods, the replication controller can remove extra pods or vice-versa.
Kubernetes can handle the availability of both applications and infrastructure. It tackles:
Health Checks: Kubernetes makes sure that application doesn’t fail by constantly checking the health of modes and containers. Kubernetes offers self-healing and auto replacement if a pod crashes due to an error.
Traffic Routing and Load Balancing: Kubernetes load balancer distributes the load across multiple loads, enabling you to balance the resources quickly during incidental traffic or batch processing.
Designed for Deployment:
Containerization has an ability to speed up the process of building, testing, and releasing software, and useful feature includes:
Automated Rollouts and Rollbacks: Kubernetes handles the new version and updates for your app without downtime, while also monitoring the health during roll-out. If any failure occurs during the process, it automatically rolls back.
Canary Deployments: Kubernetes tests the production of new deployment and the previous version in parallel, i.e. before scaling up the new deployment and simultaneously scaling down the previous deployment.
Programming Language and Framework Support: Kubernetes supports most of the programming languages and frameworks like Java, .NET, etc., and has also got a great support from the development community. If an application has the ability to run in a container, it can run in Kubernetes as well.
Some More Things to Look For
Kubernetes provides DNS management, resource monitoring, logging, storage orchestration and also addresses security as one of the primary things. For instance, it makes sure that information like passwords or ssh keys are stored securely in Kubernetes secrets. New features are released constantly and can be on the Kubernetes GitHub.
Kubernetes and Stateful Containers
Kubernetes StatefulSets provides resources like volumes, stable network ids, and ordinal indexes from 0 to N etc. to deal with stateful containers. Volume is one such key feature that enables to run the stateful application. Two main type of volume supported are:-
Ephermal Storage Volume:
Ephermal data storage is different than Docker. In Kubernetes, the volume is taken into account any containers that run within pod and data is stored across the container. But, if pods get killed, the volume is automatically removed.
Here the data remains for the lifetime. When the pod dies or it is moved to another node, that data will still remain until it is deleted by the user. Hence, data is stored remotely.
Kubernetes: Laying the Pillars to Develop Cloud Apps
Some of the container management and orchestration tools like Apache Mesos with Marathon, Docker Swarm, and AWS EC2 Container Service offer great features but weighs less than Kubernetes.
Docker Swarm is bundled tightly with Docker runtime; hence it is easy to shift from Docker to Swarm and vice-versa. Mesos with Marathon can deploy any kind of application and is just not limited to containers. AWS ECS can be easily accessible by current AWS users.
As and when this framework got matured, they started to duplicate with other tools in terms of features and functionality. But, Kubernetes is the one that is unique from all and will remain popular due to its architecture, innovation and a large open source community.
Kubernetes paves the way for DevOps by enabling the team to keep pace with the requirements for the software development. Without Kubernetes, software development teams need to script down their own software deployment, scale it manually, and update workflows. In a large enterprise, a huge team handles this task alone. Kubernetes helps to leverage maximum utility from containers and enable to develop cloud apps regardless of the cloud-specific requirements.
Other than that, enterprises are using Kubernetes because it can be deployed in the company’s pre-existing data center on-premise in one of the public cloud environment and can even run as a service. Because Kubernetes abstracts the underlying infrastructure layer, developers can focus on developing applications and then deploy them to any those environments. This increases the company’s adoption for Kubernetes as it can run on-premise while continuing to build any cloud strategy.
The Real-World Use Cases of Kubernetes
Pokémon Go – The online multiplayer game is one of the popular games showing the power of Kubernetes. Before its release, this game was expected to be reasonably the most-talked about game. But after its release, it received 50 times more than expected traffic. By using Kubernetes, Pokémon Go was able to scale high to keep pace with the unexpected demand.
Pearson – Pearson is a global education company serving 75 million learners, with a goal to reach 200 million by 2025. But as and when they climb the ladders, they faced difficulties in scaling and adapting the online audience. They were in the need of a platform that helped to scale and adapt the online audience and deliver the product faster. Hence, they deployed Kubernetes container orchestration because of its flexibility. After implementing this platform, there were the substantial improvements in the productivity and speed of delivery. Things which took nine months to provision physical assets in a data center were reduced to just a few minutes to provision.
Pinterest – Pinterest is a very popular social networking platform grown into 1000 microservices and had a varied set of tools and platforms. The company wanted to deploy the fastest path of production without making developers worry about infrastructure. The team looked for a container orchestration platform like Kubernetes to simplify overall deployment and management of complicated infrastructure. After deploying Kubernetes, the company reduced builds times and efficiency was at its peak.
Top Industries that Use Kubernetes
Ref link: idatalabs.com/tech/products/kubernetes
Looking to Use Kubernetes? Will Your Existing Architecture Need a Change?
Startup process may take time:
When you create a new deployment, you need to wait for your app to start before it is available to the end users. This can be a hurdle if the development process calls for developing new instances. While migrating to Kubernetes, you need to make some changes in the codebase to make the startup process more efficient so that the end-user doesn’t have a bad user experience.
Migrating to a stateless application requires much effort:
Kubernetes has the ability to scale pods up and down during deployment. But, if your application is not clustered or stateless, this functionality is of no use as extra pods will not get configured and can’t be utilized. The process of utilizing stateless in Kubernetes is not worth it as you will need to rework the configurations within your applications.
In a short span of time, Kubernetes has grown and developed into an economic powerhouse. As it offers varied benefits, many companies of all sizes look to develop products and services to meet an ever-increasing need. Kubernetes has an ability to work on both public and private cloud and has made it one of the favorite tools for the businesses that work with hybrid clouds. If this continues, we can even see more companies investing in Kubernetes and container management system.
Published at DZone with permission of Ankit Kumar . See the original article here.
Opinions expressed by DZone contributors are their own.