Kubernetes Core Services For Beginners (Zero to Hero Series) - Part 1

In this blog, we are going to cover Kubernetes Core services for beginners that help build, deploy, and scale containerized applications across different environments. You will learn these services in detail, which are key components for managing clusters in Kubernetes.

Kubernetes, often abbreviated as K8s, is an open-source platform that automates container operations. It eliminates many of the manual processes involved in deploying and scaling containerized applications. Kubernetes enables you to efficiently manage and orchestrate containers in production environments.

We are going to cover an overview of each of the following services:

• Kubernetes Architecture
• Kubernetes Cluster Components
• Workloads (Pods, Deployments, StatefulSets, DaemonSets)
• Services and Networking
• Storage in Kubernetes
• Security in Kubernetes
• Monitoring and Logging
• FAQs

Kubernetes Architecture

Kubernetes follows a client-server architecture that comprises a master node (control plane) and worker nodes. The control plane manages the state of the cluster, including scheduling and deploying applications, while worker nodes execute the applications in containers. The architecture is built to ensure high availability, scalability, and self-healing capabilities.

Key Components of Kubernetes Architecture:

• Control Plane: Manages the state of the cluster, including scheduling, node communication, and lifecycle of the workloads.
• Nodes: Physical or virtual machines that run containerized applications.
• Kubelet: Ensures that containers are running as expected on each node.
• Kube-Proxy: Manages networking and service discovery between pods.

Kubernetes Cluster Components

Kubernetes is organized into a set of components that work together to ensure the effective orchestration of containers.

1. API Server: Exposes the Kubernetes API, serving as the front-end of the control plane.
2. Scheduler: Determines which nodes are suitable for hosting a given workload.
3. Controller Manager: Handles background tasks such as scaling, health checks, and ensuring desired state configuration.
4. etcd: A distributed key-value store that Kubernetes uses to maintain cluster state.

Workloads in Kubernetes

Kubernetes provides a range of workloads for running containers across your clusters:

1. Pods: The smallest, most basic deployable units in Kubernetes, containing one or more containers.
2. Deployments: Manage stateless applications with desired replicas, rolling updates, and rollbacks.
3. StatefulSets: Ideal for stateful applications that require stable, unique network identifiers and persistent storage.
4. DaemonSets: Ensure that a copy of a pod is running across all nodes for purposes such as monitoring or logging.

Services and Networking

Kubernetes abstracts networking to ensure that containers can communicate both within and outside the cluster.

1. ClusterIP: Exposes services internally within the cluster.
2. NodePort: Opens a specific port on all nodes to expose services externally.
3. LoadBalancer: Automatically provisions a load balancer to expose services to the internet.
4. Ingress: Manages external access to services, typically HTTP.

Kubernetes also supports networking plugins for setting up virtual networks, like Flannel, Calico, and Cilium.

Storage in Kubernetes

Kubernetes provides a dynamic and flexible storage system that works with various storage providers:

1. Persistent Volumes (PV): A storage unit in the cluster that persists beyond the life of a pod.
2. Persistent Volume Claims (PVC): Allow users to request storage resources without knowing the underlying infrastructure.
3. Storage Classes: Provide a way to define different types of storage, such as SSDs or HDDs, for different use cases.

Kubernetes supports dynamic provisioning of storage and allows applications to use storage that can scale with demand.

Security in Kubernetes

Kubernetes offers a comprehensive security model that includes:

1. Role-Based Access Control (RBAC): Limits access to resources in the cluster.
2. Network Policies: Define how pods communicate with each other and external services.
3. Secrets and ConfigMaps: Manage sensitive information, such as passwords, without embedding them in application code.
4. Pod Security Policies: Enforce security controls on pods, such as running containers as non-root users.

Monitoring and Logging

Monitoring and logging are essential for operating Kubernetes at scale.

1. Prometheus: A popular monitoring and alerting toolkit that integrates seamlessly with Kubernetes.
2. Grafana: Provides visualizations and dashboards for metrics collected by Prometheus.
3. Fluentd/Elasticsearch/Kibana (EFK): A common logging stack used to collect, analyze, and visualize logs from containers.

FAQs

What are the core components of Kubernetes?

• The core components are the control plane (API server, scheduler, controller manager, etcd) and worker nodes (kubelet, kube-proxy).

What is a Pod in Kubernetes?

• A pod is the smallest deployable unit in Kubernetes, representing a single instance of a running process in your cluster.

How does Kubernetes handle scaling?

• Kubernetes automatically scales applications up or down by creating or deleting pods based on the defined state in the deployment configuration.

What is the difference between a Deployment and a StatefulSet?

• Deployments are used for stateless applications, while StatefulSets are used for stateful applications that require persistent data storage.

---

By covering the core components, workloads, networking, storage, and security aspects of Kubernetes, you will be better prepared to manage containerized applications efficiently. Whether you are deploying simple applications or large-scale microservices, Kubernetes provides the tools needed to ensure scalability, resilience, and flexibility.