🕸️Introduction to Kubernetes Namespaces
What is Kubernetes?
- Kubernetes is like a master organizer for your applications. It ensures your software runs smoothly, scales when necessary, and maintains a well-organized environment.
The Importance of Namespaces
Think of Kubernetes as a manager of a massive playground with various games. To prevent games from overlapping or interfering with one another, Kubernetes uses Namespaces.
Namespaces are like designated areas in the playground, ensuring your soccer game doesn't disrupt the tag game next door.
Definition: In Kubernetes, a Namespace is a logical, virtual cluster within a physical Kubernetes cluster. It allows you to create distinct environments, each with its own set of resources and access controls.
🕸️Kubernetes Initial (Default) Namespaces
In Kubernetes, several initial namespaces serve specific roles. These namespaces are created by default when you set up a Kubernetes cluster. Understanding these namespaces is crucial for managing Kubernetes resources effectively.
Default Namespace
Purpose: The
defaultnamespace is the default location for resources created without specifying a namespace. It serves as the default namespace for resource creation unless otherwise specified.Use Cases: It's commonly used for small-scale or early-stage projects where resource isolation isn't a top priority.
Example: If you create a pod without specifying a namespace, it will be placed in the
defaultnamespace:
kubectl create pod my-pod
kube-system Namespace
Purpose: The
kube-systemnamespace is dedicated to system-level Kubernetes resources, including those created by Kubernetes itself. It houses essential components like the Kubernetes API server, the scheduler, and the DNS server.Use Cases: It's designed for managing cluster-level components separately from user applications.
Example: To list all resources in the kube-system namespace, you can use:
kubectl get all -n kube-system
kube-public Namespace
Purpose: The
kube-publicnamespace is reserved for resources accessible to all users, even those without specific RBAC permissions. It's a space for sharing cluster-wide information.Use Cases: It's typically used for resources like ConfigMaps that need to be globally visible.
Example: To create a ConfigMap in the
kube-publicnamespace:
kubectl create configmap my-configmap --namespace=kube-public
kube-node-lease Namespace
Purpose: The
kube-node-leasenamespace is a new addition, introduced in Kubernetes 1.14. It's part of the Node Heartbeat feature, where nodes periodically lease node conditions to the control plane.Use Cases: This namespace is primarily for internal Kubernetes use and is typically not manipulated by users or administrators.
Example: User-initiated actions are typically not performed in this namespace.
kube-ingress Namespace
Purpose: The
kube-ingressnamespace is often used for Ingress Controllers, which manage external access to services within the cluster.Use Cases: It's used for managing Ingress resources that control traffic routing into the cluster.
Example: To deploy an Ingress Controller in the
kube-ingressnamespace:
kubectl create deployment my-ingress-controller --namespace=kube-ingress --image=my-ingress-controller-image
🕸️Resource Management with Namespaces
Resource management is critical in Kubernetes to ensure fair resource allocation among different applications or teams. Kubernetes allows you to define resource quotas and limits at the namespace level.
Controlling Resources
Resource management in Kubernetes is akin to having referees oversee a game. Kubernetes uses Resource Quotas and Limits to manage resources within Namespaces.
Resource Quotas: These are limits on resources, much like setting the maximum number of soccer balls your team can have. Kubernetes ensures you don't exceed these quotas.
Resource Limits: These are akin to saying, "Each player can't use more than this much energy." It ensures that resource usage remains fair.
Use Cases:
Team Isolation: If multiple teams share a Kubernetes cluster, assigning each team to a separate namespace helps prevent resource conflicts. You can set resource quotas to ensure fair allocation.
Resource Guarantees: Critical applications can be assured a minimum level of resources within a namespace, safeguarding them from resource shortages caused by other applications.
Example: To create a ResourceQuota in a namespace:
apiVersion: v1
kind: ResourceQuota
metadata:
name: my-resource-quota
spec:
hard:
pods: "10"
requests.cpu: "4"
requests.memory: 4Gi
limits.cpu: "8"
limits.memory: 8Gi
In this example, we define a ResourceQuota that limits the number of pods, CPU requests, CPU limits, memory requests, and memory limits within the namespace.
🕸️Creating and Managing Custom Namespaces
Creating a custom namespace in Kubernetes is straightforward using the kubectl command:
kubectl create namespace my-team-environment
This command creates a new namespace called
my-team-environment, providing a separate playground for your team's applications.Access Control: Kubernetes allows you to set RBAC (Role-Based Access Control) policies at the namespace level, controlling which users or service accounts have access to resources within a specific namespace.
Resource Quotas and Limits: Namespaces are used to set resource quotas and limits. For instance, you can define that a particular namespace should not consume more than a specified amount of CPU or memory.
Network Policies: Network policies can be applied at the namespace level, controlling how traffic is allowed or denied between pods within the same namespace or across namespaces.
let's go through the steps to create a namespace, update a deployment to use that namespace, and then apply the updated deployment.
Step 1: Create a Namespace
Use the following command to create a namespace:
kubectl create namespace <namespace-name>
Replace <namespace-name> with the desired name for your namespace.
Step 2: Update the Deployment YAML
Assuming you have a Deployment defined in a YAML file (let's call it deployment.yml), you need to specify the namespace in that file. Open the deployment.yml file and look for the metadata section. Add the namespace field under metadata and set it to your chosen namespace name. Here's an example:
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-deployment
namespace: <namespace-name> # Add this line with your namespace name
Step 3: Apply the Updated Deployment
Now, apply the updated deployment YAML using the following command:
kubectl apply -f deployment.yml -n <namespace-name>
Replace <namespace-name> with the same namespace name you used in the previous steps.
Step 4: Verify the Namespace
To verify that the namespace has been created and the deployment is running in that namespace, you can list the namespaces and check the status of your deployment:
List all namespaces:
kubectl get namespaces
Check the status of your deployment in the specified namespace:
kubectl get deployment -n <namespace-name>
You should see your deployment listed, indicating that it's running within the specified namespace.
That's it! You've successfully created a namespace, updated a deployment to use that namespace, and verified the namespace and deployment status in your Kubernetes cluster.
I hope now you can create your own namespace
Happy Learning