Kubernetes is a portable, extensible, open-source platform, which enables multiple containers to work collectively, and automates manual processes, like deploying, managing, and scaling, containerized applications.
Kubernetes evolution
Kubernetes gets its name from Greek, which means helmsman or governor or pilot. Kubernetes is also known as k8s (the eight alphabets between K and s) or kube.
Kubernetes has a large and rapidly growing ecosystem and manages application containers across multiple hosts. Kubernetes clusters can host across public, private, or hybrid clouds. Thus, Kubernetes can be used for hosting cloud-native applications that need rapid scaling.
Earlier, companies ran applications on physical servers before the existence of Kubernetes. It was difficult for users to allocate the resource boundaries for software applications in a physical server, which led to resource allocation issues. For example, when you run multiple applications on a physical server, there can be occurrences where one application would take up most of the resources, and thus the other applications would not get the resources.
To avoid the resource allocation issue, you can run each application on a different physical server. However, this solution did not scale as resources were not utilized, and it was not cost-effective for companies to manage multiple physical servers.
Therefore, virtualization was introduced, in which you run multiple virtual machines (VMs) on a single physical server. The VM is a system, which runs all the components, and its Operating System (OS), in the virtualized hardware.
Image source: ResearchGate
The virtualization enables applications to be inaccessible between VMs and provides security such that the information of one application cannot be accessed by another application. The virtualization helps proper use of resources in a physical server, provides better scalability, and reduces hardware costs. In virtualization, you can use a set of physical resources as a cluster of disposable virtual machines.
Image source: MakeITSolutions
Then, came the use of containers similar to VMs with better isolation properties to share the OS among the applications. In a production environment, the containers should be managed that run the applications, and confirm that there is no downtime, that is, if a container stops, another container should start immediately. Kubernetes was then used to overcome these issues. Kubernetes provides a framework to run distributed systems collectively. Kubernetes helps to scale and identifies failover for applications, and provides deployment patterns. In 2014, Google made Kubernetes available for other users.
Image credits: RedHat
The cluster is a working Kubernetes deployment. The two parts of the Kubernetes cluster are:
- Control plane: The control plane maintains the desired state of the cluster, for example, the type of the applications running and the container images used by them.
- Compute machines: The compute machines run the applications and workloads. The compute machines are also called nodes. Each compute machine has its own Linux® environment and can be a physical or virtual machine. Each compute machine runs pods, which are made up of containers.
Kubernetes runs on an operating system and interacts with pods of containers, which run on the compute machines. The Kubernetes control plane receives the commands from an administrator or DevOps team, and sends the commands to the compute machines. Kubernetes identifies the compute machines suitable for each of the tasks and assigns the resources and pods in the compute machines to complete the requested task.
The desired state of a Kubernetes cluster defines the configuration details, such as:
- The applications or workloads running
- The images used by the applications
- The resources available for the applications
For infrastructures, the control over containers is at a higher level, which provides better control to avoid micromanaging each separate container or compute machine. You can configure Kubernetes and define compute machines, pods, and containers, and Kubernetes will arrange the containers. You can run Kubernetes on VMs, public cloud, private cloud, and hybrid cloud environments.
Advantages of using Kubernetes
- Kubernetes can orchestrate the containers across multiple hosts.
- Kubernetes can identify a container using the Domain Name System (DNS) name or their own IP address. If the traffic to a container is high, then Kubernetes balances the load and distributes the network traffic to ensure that the deployment is stable.
- Kubernetes helps you to use a storage system of your choice, like local storage, public cloud providers, private cloud providers, and so on.
- Kubernetes helps you define the desired state for the deployed containers, and it can change the actual state to the desired state at a controlled rate. For example, Kubernetes can be automated to create new containers for the deployment, eliminate the existing containers, and adopt all their resources to the new container.
- Kubernetes with a cluster of compute machines helps you to run the containerized tasks.
- Kubernetes can adjust containers onto the compute machines to make the best use of the resources.
- Kubernetes can restart the containers that fail, replace the containers, stop the containers that do not respond to the user-defined health check, and do not display them to users till they are ready to serve.
- Kubernetes can store and manage secure information. You can deploy and update the information and application configuration without rebuilding the container images, and revealing the information in the stack configuration.
- Kubernetes can scale containerized applications and their resources.
- Kubernetes can declaratively manage services, which confirms that the deployed applications are running correctly.
- Kubernetes helps you deliver the software applications quickly with better compliance
- Kubernetes helps you increase transparency and collaboration between the teams involved in delivering software.
- Kubernetes minimizes security risk and costs.
Disadvantages of using Kubernetes
- Kubernetes is very complex and can decrease productivity
- Kubernetes limits the types of applications supported.
- Kubernetes can overload simple applications.
- Kubernetes cannot deploy source code and build the application. The Continuous Integration, Delivery, and Deployment (CI/CD) workflows are determined by organizations.
- The transition to Kubernetes is complex.
- Kubernetes does not provide application-level services, like databases, caches, cluster storage systems, middleware, and so on, as built-in services. These components can run on Kubernetes and can be accessed by applications running on Kubernetes through portable mechanisms.
- Kubernetes is expensive and not cost-effective for organizations.
- Kubernetes is a crucial orchestration system.
- Kubernetes does not provide solutions for logging, monitoring, or alerting issues.
- Kubernetes does not provide or mandate a configuration language.
- Kubernetes does not provide a comprehensive machine configuration, maintenance, management, or self-healing systems.
Kubernetes as a part of your Software Development Life Cycle (SDLC)
Kubernetes helps in application development, and its operations throughout all the stages of the SDLC, such as from planning, defining, coding, building, testing, deploying, and operating and monitoring.
Kubernetes provides portability and flexibility for all the users involved in the different stages of SDLC, such as:
- Software Developer: Kubernetes helps developers to build the code once and run it everywhere.
- Tester/Quality Assurance: Kubernetes helps testers to be reliable, and coordinate the environments between test and production.
- System administrator: Kubernetes helps the system administrators to configure the system once, and run it easily.
- Operational team: Kubernetes helps the operational team to provide a single solution to build, deliver, and scale software applications. Kubernetes helps the operational team to focus on features, bugs, and deliver better software applications instead of setting up and maintaining the environment and tools.
Image source: Platform9
In SDLC, Kubernetes helps developers and system administrators to reduce config variables, and time-consuming setup and maintenance, and testers to reduce risk and improve efficiency. Kubernetes technology increases the competence and eradicates the risk by ensuring that the system configuration of the test environment is the same as the production environment.
Kubernetes is very important for SDLC as the shift of the digital wave has made software architecture complex, use of various technologies, and run-on multiple environments with multiple iterations. Kubernetes helps you manage consistency, as the infinite loop of technologies and environments.
In SDLC, Kubernetes improves for Continuous Integration (CI)/Continuous Delivery (CD), that is, you can use the code between different virtual machines in different environments, the same code can be moved across container clusters with Kubernetes. Thus, it helps to improve elasticity, high availability, and usage of resources.
Kubernetes cluster management:
Kubernetes environments are widely spread and they can be deployed across multiple data centers, like in the public cloud, private cloud, hybrid clouds, on-premise, and so on. Kubernetes has multiple clusters, like for development, testing, and production, distributed across environments, and are managed effectively. The multi-cluster Kubernetes deployment improves application availability and disaster recovery, reduces latency, and deploys legacy and cloud-native applications across environments.
Image source: Kubernetes
A Kubernetes cluster is defined as a collection of node machines to run containerized applications. You can use the Kubernetes cluster to plan and run containers across a group of machines in physical, virtual, cloud, or on-premise environments. A Kubernetes cluster has a desired state, and Kubernetes automatically manages the cluster to match the desired state.
The Kubernetes environments are managed at an individual cluster level, thus the cost of managing the cluster can increase based on the number of clusters. You deploy, upgrade, and configure each cluster individually for security purposes.
Below are the tasks involved in Kubernetes cluster management:
- Creating a new cluster
- Securing the cluster
- Upgrading the cluster
- Removing a cluster
- Updating the control plane, compute machines, and the Kubernetes API version
- Maintaining the compute machines
Software developers require easy access to new clusters as they need them very often. For Operations teams (Ops) and Site Reliability Engineers (SREs), new clusters should be configured correctly for applications are made available in production, and to monitor the health of clusters.
Kubernetes cluster management helps to overcome the challenges faced by administrators and site reliability engineers as they work across a range of environments that run Kubernetes clusters.
Kubernetes container management
Image source: Docker
A container is a software, which generates, maintains, and secures containerized applications. Kubernetes container management helps for easier and faster networking, and container orchestration. The containers maintain multiple containerized application processes, such as:
- Governance
- Automation
- Security
- Extensibility
- Enterprise support
Kubernetes container management is required when there are a greater number of containers for a single IT team to handle.
Kubernetes container management helps:
- IT administrators to maintain the security of the environment and decrease the time and resources required.
- Software Developers get flexibility, and ease of containers to develop and deploy new applications and services.
Kubernetes container management:
- Contains storage, security tools, schedulers, and monitoring systems to reduce hosting setup complexities.
- Automates various processes, such as load balancing and orchestration.
- Provides automatic health checks for applications, monitors the environment for containers that have failed or delayed.
- Helps systems to work more efficiently.
Well, Kubernetes has been around for a while and has grown rigorously all over the world. Kubernetes has become the de facto container orchestration tool in the industry today. Every company embracing a cloud-native approach has Kubernetes in their tech stack, which is considered a must. Kubernetes makes complex things very simple with its many unique features. Deploying apps on Kubernetes makes them easy to scale up and scale down accordingly. Many big companies are already using Kubernetes in production and are highly successful.
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