Kubernetes Namespaces and Best Practices

What is a Namespace?

• Namespace in Kubernetes: A virtual cluster within a Kubernetes cluster to organize resources.
• Allows multiple namespaces in a single cluster.
• Default namespaces are provided by Kubernetes out-of-the-box.

Default Namespaces

1. kube-system
   • Contains system processes and components.
   • Not meant for user modification.
2. kube-public
   • Contains publicly accessible data and cluster information config map.
3. kube-node-lease
   • Holds information about node heartbeats and availability.
4. default
   • Used initially to create resources unless others are defined.

Creating Namespaces

• Use kubectl create namespace <name> to create a new namespace.
• Recommended to use namespace configuration files for history tracking.

Why Use Namespaces?

• Organization: Group resources logically, e.g., database, monitoring, etc.
• Multiple Teams: Avoid conflicts by assigning each team its own namespace.
• Environment Separation: Host staging and development in the same cluster.
• Blue-Green Deployment: Manage different production versions in one cluster.
• Resource Limitation: Control resource usage and access within namespaces.

Namespace Characteristics

• Resources are largely isolated and cannot be accessed cross-namespace, except for services.
• Some components, like Persistent Volumes, are global and not namespace-bound.

Creating Components in a Namespace

• By default, components are created in the default namespace unless specified.
• Use kubectl apply -n <namespace> or include namespace attribute in config files.
• Configuration file approach is recommended for clarity and automation.

Switching Active Namespace

• By default, kubectl uses the default namespace.
• Use kubens tool to switch active namespace for convenience.

Tools and Commands

• kubectl: Command-line tool for managing Kubernetes.
• kubens: Tool to switch default namespaces easily.

Conclusion

• Consider isolation, resource sharing, and organizational needs when using namespaces.
• Namespaces enhance manageability in multi-team, multi-environment projects.
• Always document namespace usage in configuration files for better clarity and management.

Helpful Tips

• Use namespaces even for smaller projects to maintain order.
• Regularly review and adjust namespaces as project needs evolve.
• Utilize shared resources effectively across namespaces.