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Kubernetes Namespaces

Links: 110 Kubernetes Index

Namespaces

  • Namespaces are a way to organise clusters into virtual sub-clusters by keeping objects separate — they can be helpful when different teams or projects share a Kubernetes cluster.
  • These namespaces are logically separated from each other but can communicate with each other.
    • Namespace groups isolate k8s objects across nodes.
  • Test and production objects are in different namespaces in the same cluster.
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  • Creating a component in a namespace

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  • Kubernetes comes with four namespaces out-of-the-box. They are:

    • default: As its name implies, this is the namespace that is referenced by default for every Kubernetes command, and where every Kubernetes resource is located by default.
    • kube-system: Used for Kubernetes components and should be avoided.
    • kube-public: Used for public resources. Not recommended for use by users.
    • kube-node-lease: This namespace holds Lease objects associated with each node.
      • Node leases allow the kubelet to send heartbeats so that the control plane can detect node failure.
Until new namespaces are created, the entire cluster resides in default.

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If you are going to work on a particular namespace a lot then you can change your default namespace from default to that particular namespace.
  • Whenever you issue a kubectl command you are targeting the default namespace unless specified otherwise.
  • If you want it to look into another namespace use -n namespace
Somethings cannot be namespaced such as nodes, persistent volume etc.

Use cases of Namespaces

  • Allowing teams or projects to exist in their own virtual clusters without fear of impacting each other’s work.
  • Enhancing role-based access controls (RBAC) by limiting users and processes to certain namespaces.
  • Only certain users can push to production
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  • Enabling the dividing of a cluster’s resources between multiple teams and users via resource quotas.
  • Providing an easy method of separating development, testing, and deployment of containerised applications enabling the entire lifecycle to take place on the same cluster.

Last updated: 2022-08-28