Why do you need Kubernetes? What Kubernetes is not?

Kubernetes is an open-source platform that automates the deployment, scaling, and management of containerized applications.

Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation.

Going back in time:

Let's take a look at why Kubernetes is so useful by going back in time.

Traditional deployment:

Early on, organizations ran applications on physical servers. There was no way to define resource boundaries for applications in a physical server, and this caused resource allocation issues.

For example, if multiple applications run on a physical server, there can be instances where one application would take up most of the resources, and as a result, the other applications would underperform. A solution for this would be to run each application on a different physical server. However this did not scale as resources were underutilized, and it was expensive for organizations to maintain many physical servers.

Virtualized deployment:

As a solution, virtualization was introduced. It allows you to run multiple Virtual Machines (VMs) on a single physical server's CPU.

Virtualization allows applications to be isolated between VMs and provides a level of security as the information of one application cannot be freely accessed by another application.

Virtualization allows better utilization of resources in a physical server and allows better scalability because an application can be added or updated easily, reduces hardware costs, and much more. With virtualization, you can present a set of physical resources as a cluster of disposable virtual machines.

Each VM is a full machine running all the components, including its own operating system, on top of the virtualized hardware.

Container deployment:

Containers are similar to VMs, but they have relaxed isolation properties to share the Operating System (OS) among the applications.

Therefore, containers are considered lightweight. Similar to a VM, a container has its own filesystem, share of CPU, memory, process space, and more. As they are decoupled from the underlying infrastructure, they are portable across clouds and OS distributions.

Containers have become popular because they provide extra benefits, such as:

1. Portability: Containers encapsulate an application and its dependencies, including libraries and configurations. This makes it easy to move applications across different environments, such as development, testing, and production, without worrying about compatibility issues.
2. Consistency: Containers ensure consistency between development and production environments. Since the entire runtime environment is packaged with the application, there are fewer chances of "it works on my machine" issues, promoting reliable deployments.
3. Isolation: Containers provide a level of isolation between applications and their dependencies. Each container runs in its own user space, making it less prone to conflicts with other applications or system components. This isolation helps in maintaining security and prevents interference between applications.
4. Resource Efficiency: Containers share the host operating system's kernel, which means they are more lightweight compared to traditional virtual machines. This results in faster startup times and efficient resource utilization, enabling the deployment of more containers on a single host.
5. Scalability: Containers can be easily scaled up or down based on demand. This flexibility allows for efficient resource allocation and helps in building scalable, responsive applications.
6. Microservices Architecture: Containers are well-suited for microservices architectures, where applications are broken down into smaller, independent services. Each microservice can run in its own container, facilitating easier development, deployment, and maintenance of complex applications.
7. DevOps Practices: Containers align well with DevOps principles by enabling continuous integration and continuous deployment (CI/CD) pipelines. Containers make it easier to automate the build, test, and deployment processes, reducing manual intervention and speeding up the development lifecycle.
8. Versioning and Rollback: Containers support versioning, making it straightforward to roll back to a previous version in case of issues. This capability is crucial for maintaining system reliability and ensuring quick recovery from failures.
9. Ecosystem Support: Containers have a rich ecosystem of tools and orchestration platforms, such as Docker, Kubernetes, and others, that facilitate the management and deployment of containerized applications at scale.
10. Resource Utilization: Containers share the host OS's kernel and use resources more efficiently compared to traditional virtual machines. This allows for a higher density of applications on a single host, leading to better resource utilization.

Why you need Kubernetes and what it can do

Containers are a good way to bundle and run your applications. In a production environment, you need to manage the containers that run the applications and ensure that there is no downtime.

For example, if a container goes down, another container needs to start. Wouldn't it be easier if this behavior was handled by a system?

That's how Kubernetes comes to the rescue! Kubernetes provides you with a framework to run distributed systems resiliently. It takes care of scaling and failover for your application, provides deployment patterns, and more.

Kubernetes provides you with:

1. Container Orchestration: Kubernetes excels at orchestrating containers, providing a platform for automating the deployment, scaling, and management of containerized applications. It abstracts away the complexities of container deployment and allows developers to focus on building and scaling their applications.
2. Scalability: Kubernetes enables automatic scaling of applications based on demand. It can scale applications up or down by adjusting the number of running containers, ensuring that the right amount of resources are allocated to meet varying workloads.
3. Portability: Kubernetes provides a consistent environment across various infrastructure providers and on-premises data centers. This portability allows developers to write their applications once and deploy them anywhere that Kubernetes is supported.
4. Service Discovery and Load Balancing: Kubernetes automates the discovery of services and load balancing across containers. It ensures that traffic is distributed evenly, improving application availability and responsiveness.
5. Rolling Updates and Rollbacks: Kubernetes supports rolling updates, allowing for seamless deployment of new versions of applications without downtime. If issues are detected after an update, Kubernetes facilitates quick rollbacks to the previous stable version.
6. Resource Efficiency: Kubernetes optimizes resource utilization by efficiently packing containers onto nodes, allowing for better overall system performance. It supports the coexistence of multiple applications on the same cluster without interference.
7. Declarative Configuration: Kubernetes uses declarative configuration files to define the desired state of applications and infrastructure. This allows for easier management and version control of configuration settings.
8. Community Support: Kubernetes has a large and active open-source community. This community-driven development model leads to continuous improvement, innovation, and a wealth of available resources, including documentation, tutorials, and third-party tools.
9. Ecosystem Integration: Kubernetes has a rich ecosystem of tools and extensions that complement its core functionality. This ecosystem includes monitoring solutions, logging tools, continuous integration/continuous deployment (CI/CD) pipelines, and more.
10. Hybrid and Multi-Cloud Support: Kubernetes supports hybrid and multi-cloud deployments, allowing organizations to run applications seamlessly across on-premises data centers and multiple cloud providers. This flexibility is crucial for businesses with diverse infrastructure requirements.
11. Security Features: Kubernetes provides various security features, such as network policies, RBAC (Role-Based Access Control), and encryption, to help secure containerized applications and the underlying infrastructure.
12. Self-healing Kubernetes restarts containers that fail, replace containers, kill containers that don't respond to your user-defined health check, and don't advertise them to clients until they are ready to serve.
13. Secret and configuration management Kubernetes lets you store and manage sensitive information, such as passwords, OAuth tokens, and SSH keys. You can deploy and update secrets and application configuration without rebuilding your container images, and without exposing secrets in your stack configuration.
14. Horizontal scaling Scale your application up and down with a simple command, with a UI, or automatically based on CPU usage.
15. Designed for extensibility Add features to your Kubernetes cluster without changing upstream source code.

What Kubernetes is not?

While Kubernetes is a powerful container orchestration platform with numerous benefits, it's important to understand what Kubernetes is not.

Here are some aspects and misconceptions about Kubernetes:

1. Not a Containerization Technology:Kubernetes is not a containerization technology itself. It works with container runtimes like Docker, containers, or others to manage and orchestrate containerized applications. Kubernetes focuses on the deployment, scaling, and management of containers rather than creating them.
2. Not a PaaS (Platform as a Service):Kubernetes is often mistaken for a Platform as a Service (PaaS) solution. Unlike traditional PaaS offerings that abstract away infrastructure details, Kubernetes is more of a container orchestration framework that provides a level of abstraction for managing containers but requires more manual configuration and management.
3. Not a Replacement for Configuration Management Tools:While Kubernetes provides declarative configuration and allows you to define the desired state of applications, it is not a replacement for traditional configuration management tools like Ansible, Chef, or Puppet. These tools are still relevant for configuring and managing the state of the underlying infrastructure.
4. Not a Magic Solution for All Problems:Kubernetes is a powerful tool, but it may not be the best solution for every application or organization. Smaller applications with simple deployment requirements might find simpler solutions more suitable. Kubernetes introduces complexity, and its benefits are most apparent in large, complex, and dynamic environments.
5. Not a Monitoring or Logging Solution:While Kubernetes has basic monitoring capabilities, it is not a dedicated monitoring or logging solution. Organizations often integrate Kubernetes with additional tools such as Prometheus for monitoring and Fluentd or Elasticsearch for logging to enhance observability.
6. Not Immune to Learning Curve:Kubernetes has a steep learning curve, especially for beginners. It requires understanding various concepts such as pods, services, deployments, and more. Additionally, managing and troubleshooting Kubernetes clusters efficiently demands familiarity with its command-line tools and API.
7. Not a Substitute for Application Design Best Practices:Kubernetes can facilitate certain aspects of application scaling and deployment, but it does not replace the need for well-designed and scalable applications. Application architecture and design still play a crucial role in achieving optimal performance and scalability.
8. Not Necessarily Cost-Effective for Small Applications:For small-scale applications with minimal infrastructure requirements, the overhead of setting up and managing a Kubernetes cluster may outweigh the benefits. Simpler deployment solutions may be more cost-effective and easier to manage for such scenarios.

Understanding these aspects helps in making informed decisions about whether Kubernetes is the right solution for a particular use case or organization. While Kubernetes is a versatile and widely adopted platform, it may not be the best fit for every application or deployment scenario.