Day 44 - Kustomize Tutorial For Beginners | Kubernetes Kustomized Simply Explained (with demo)

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### Comprehensive Final Summary The document provides a detailed exploration of **Kustomize**, a Kubernetes deployment tool, as part of an extended Kubernetes series by Pyush. The series extends beyond its original 40-day scope due to updates in the CKA (Certified Kubernetes Administrator) curriculum by the Linux Foundation on February 18, 2025. This summary consolidates key insights into Kustomize's features, workflow, and advanced concepts, with practical examples and comparisons to Helm. --- ### **1. Introduction and Context** - **Purpose**: The session focuses on Day 44 of the series, introducing **Kustomize** as an alternative to Helm for managing Kubernetes deployments. - **Comparison to Helm**: Unlike Helm, which uses templating to manage Kubernetes manifests, Kustomize employs a layered approach without templates, simplifying environment-specific customizations. --- ### **2. Key Differences Between Helm and Kustomize** - **Helm**: - A package manager for Kubernetes that bundles manifests into "charts." - Relies on templating for environment-specific customizations, which can become complex for production-grade applications. - **Kustomize**: - Avoids templating and instead uses a folder structure to layer configurations. - Allows easier management of multiple environments by overriding base configurations through YAML files. --- ### **3. Core Features of Kustomize** - **Base Configuration**: - Contains common files shared across all environments (e.g., deployment templates, services, ConfigMaps). - Includes metadata like labels, annotations, and name prefixes/suffixes applicable globally. - **Environment-Specific Customizations**: - Separate directories for each environment (e.g., dev, test, staging, production) where only necessary changes are specified. - Uses patches and overrides to modify base configurations without duplicating them. - **No Templating**: - Leverages existing YAML files and applies environment-specific changes via child YAML files. --- ### **4. Workflow Overview** - **Folder Structure**: - Organizes files into a `base` folder (common configuration) and an `overlays` folder (environment-specific changes). - **kustomization.yaml**: - A central file in each directory declaring resources (e.g., deployments, services, ConfigMaps). - **Commands**: - Use `kubectl kustomize` to preview the final YAML output after applying overlays. - Apply changes using `kubectl apply`, creating resources in the specified namespace. --- ### **5. Demo Walkthrough** - **Sample Application**: - Explored a 3-tier application with separate folders for frontend, backend, and database. - **Practical Steps**: - Created a `kustomization.yaml` file in the root directory to import all resources. - Applied changes using `kubectl kustomize` and verified deployments with commands like `kubectl get pods` and `kubectl get services`. --- ### **6. Advanced Concepts** - **Overlays**: - Used for managing multiple environments with minimal duplication. - Each environment folder contains its own `kustomization.yaml` file for specific customizations. - **Customization Features**: - **Patches**: Override specific fields in the base configuration (e.g., replicas, resource limits). - **ConfigMap Generators**: Dynamically generate ConfigMaps based on files (e.g., `index.html`) in each environment folder. - **Common Labels**: Apply consistent labels across resources. - **Service Customization**: - Modify services per environment (e.g., changing from `ClusterIP` to `NodePort` for external access). --- ### **7. Testing and Deployment** - **Preview Changes**: - Use `kubectl kustomize` to review the final YAML output before applying changes. - **Apply Resources**: - Deploy resources using `kubectl apply`, ensuring they are created in the correct namespace. - **Example Scenarios**: - The `dev` environment might have 1 replica with specific resource limits. - The `test` environment could have 3 replicas and different limits. --- ### **8. Benefits of Kustomize** - **Avoids Duplication**: - Common configurations are centralized in the `base` folder, reducing redundancy. - **Simplifies Management**: - Environment-specific changes are isolated in `overlays`, making it easier to manage and deploy updates. - **Ensures Consistency**: - Maintains consistency across environments while allowing flexibility for customization. --- ### **9. Hands-On Example** - **Folder Structure**: - Demonstrated creating a folder structure with `base` and `overlays` directories. - **Practical Application**: - Walked through creating and applying `kustomization.yaml` files for different environments. - Showcased how to

Course: Certified Kubernetes Administrator Full Course For beginners | CKA 2025

This playlist contains the complete CKA series for beginners, based on the latest 2025 curriculum. It includes 40+ videos with hands-on demos, assignments, and exam-based scenarios. We will cover everything from the basics to the Advanced, including fundamental concepts such as Docker, containers, Docker storage and networking, DNS, etc.