This article provides a basic overview of the structure, mechanisms, and benefits of Kubernetes for beginners.
What is Kubernetes (k8s)?
Kubernetes is an open-source container orchestration tool that helps in the operational management and scaling of containers. Kubernetes is often abbreviated as k8s, which shortens the name to its first and last letters, with an 8 representing the eight letters between them.
Kubernetes eliminates the need for manual processes like deploying containerized applications. This allows development teams to manage container runtimes in clusters, scale resources during increased load, and ensure redundancy and high availability of their applications.
By automating the distribution and scheduling of containers across a cluster, Kubernetes simplifies both the scalability and maintenance of applications, enabling more resilient and efficient operations.
Key features and overview of Kubernetes
By utilizing k8s, you can manage clusters, provide a standardized infrastructure, offer common operational environments, utilize monitoring and autoscaling functions, and more. Kubernetes targets systems compatible with container runtimes and provides system management functionalities that standalone container tools like Docker lack.
Here are some of the important features of Kubernetes:
- Container orchestration: Managing the lifecycle of containers in various environments
- Automated deployment and updates: Streamlining the deployment process and updating applications without downtime
- Automatic scaling: Dynamically adjusting the number of active containers based on the load or other indicators
- Efficient release management: Facilitating controlled exposure of new features through canary deployments and feature flags
- Rolling updates: Updating applications with zero downtime by incrementally updating pod instances with new ones
- Self-healing: Automatically replacing or restarting containers that fail, do not respond, or do not meet user-defined health checks
Why is Kubernetes crucial for businesses?
Kubernetes is an important tool for many businesses, especially as they adopt cloud-native technologies. It offers a consistent and portable platform that simplifies the management of containerized applications across different cloud environments—be it private, public, or hybrid.
This uniformity ensures that teams can deploy, manage, and scale their applications without needing to tailor them to the specifics of each cloud provider.
Additionally, Kubernetes supports Agile development practices by enabling faster deployments, on-demand scaling, and rapid rollbacks. Its robust ecosystem of tools and large community also provide extensive support for continuous integration and continuous delivery (CI/CD) processes, making it easier for teams to maintain high standards of quality and reliability in their software releases.
Key Kubernetes features and terminology
Kubernetes includes structural elements and terminologies such as nodes and clusters. Nodes are the “machines”–either physical or virtual—where applications are run. Clusters are collections of nodes grouped together, including both the worker nodes that run applications and the control plane that manages and coordinates the cluster.
Components of the control plane
The control plane is the core of Kubernetes, orchestrating all cluster activities such as deploying applications, managing their states, scaling services, and handling failures. It is made up of the following elements:
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etcd saves cluster information to a reliable distributed data store.
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kube-scheduler assigns containers (pods) to worker nodes.
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kube-controller-manager manages multiple controller functions that regulate cluster states.
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Cloud-controller-manager coordinates resources from Azure, GCP, and other platforms.
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kube-apiserver provides the Kubernetes API, allowing external interaction with the cluster.
Note: In managed Kubernetes services like AWS EKS, GCP GKE, or Azure AKS, the control plane nodes are managed by the service provider, eliminating the need for users to manage them directly.
Components of worker nodes
Nodes house components that manage and run the containers:
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Kubelet is an agent that ensures containers are running as expected on nodes.
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Kube-proxy manages network communication within the cluster, including maintaining network rules.
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Container runtime is the software, such as Docker, that is responsible for running containers.
Other important Kubernetes resources
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Pods handle containers as a resource. Pods can utilize shared storage (volumes) and can contain multiple containers.
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ReplicaSet ensures that a specified number of pod replicas are running at any given time. It guarantees the availability of a specified number of identical pods, helping with scaling, redundancy, and fault tolerance.
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Deployment manages the deployment, scaling, updating, and rollback of pods via ReplicaSets.
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Service assigns endpoints and IP addresses to scattered pods, enabling communication and load balancing. Pods can be accessed only with a service.
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Ingress is a resource that exposes routes for HTTP and HTTPS from outside the cluster to internal services. It also provides functionalities like virtual hosting and SSL termination.
Differences between Kubernetes and Docker
The primary difference between Kubernetes and Docker lies in their roles and capabilities.
Docker is a platform and tool for building, distributing, and running Docker containers. It enables you to package an application with all of its dependencies into a standardized unit for software development.
Kubernetes, on the other hand, does not do any container runtime on its own but provides container orchestration. This means Kubernetes manages the containers that run the applications, handling tasks such as deployment, scaling, and networking across a cluster of machines.
While Docker excels at running containers on a single node, Kubernetes excels at managing and scaling applications across multiple nodes. Both platforms use YAML for configuration, which simplifies the deployment and management processes.
Note: Docker offers a container orchestration tool called Docker Swarm, which can also be used for scheduling and clustering. To learn about how it compares to Kubernetes and which solution might be best for you, check out Docker Swarm vs Kubernetes: How to choose a container orchestration tool.
Kubernetes and CI/CD
Kubernetes plays an important role in continuous integration and continuous deployment (CI/CD) processes by simplifying the deployment and management of containerized applications and services across environments. Its ability to handle large-scale orchestration makes it a key component in modern DevOps practices, ensuring that applications are consistently deployed, scaled, and managed with high availability and resilience.
CircleCI enhances the capabilities of Kubernetes in CI/CD pipelines by automating Kubernetes deployments, which promotes more consistent and reliable delivery cycles. CircleCI also supports Docker and integrates with container registries, deployment services, and more. With the use of the Kubernetes orb, you can automate Kubernetes operations with just a few lines of YAML code.
Sign up for a free CircleCI trial and make managing your Kubernetes deployments more efficient and flexible than ever before.
Conclusion
Kubernetes has become an essential tool for managing containerized applications at scale, providing a robust framework for automating deployment, scaling, and operations of application containers across clusters of hosts.
Whether you are operating on a single cloud, multicloud, or hybrid cloud environment, Kubernetes provides the versatility and scalability you need to handle complex deployments and dynamic workloads effectively.
