kubectl resource management¶

kubectl resource management involves using the kubectl command-line tool to perform imperative (command-based) and declarative (configuration file-based) operations on Kubernetes resources such as Namespaces, Deployments, Pods, and Services^[400-devops-06-kubernetes-k8s-paas-03k8s.md].

Namespace Management¶

Namespaces (ns) are used to segregate resources within a cluster.^[400-devops-06-kubernetes-k8s-paas-03k8s.md]

• List namespaces:

  [kubectl](<./kubectl.md>) get namespace
  # or
  [kubectl](<./kubectl.md>) get ns
  

• Create: kubectl create ns <name>^[400-devops-06-kubernetes-k8s-paas-03k8s.md]
• Delete: kubectl delete namespace <name>^[400-devops-06-kubernetes-k8s-paas-03k8s.md]

Deployments and Pods¶

Deployments manage the state of Pods, ensuring a specified number of replicas are running.^[400-devops-06-kubernetes-k8s-paas-03k8s.md]

Creation¶

Deployments can be created directly from the command line.^[400-devops-06-kubernetes-k8s-paas-03k8s.md]

[kubectl](<./kubectl.md>) create deployment <name> --image=<image-url> -n <namespace>

Scaling¶

The number of Pod replicas can be adjusted dynamically using the scale command^[400-devops-06-kubernetes-k8s-paas-03k8s.md].

[kubectl](<./kubectl.md>) scale deployment <name> --replicas=<number> -n <namespace>

Deletion¶

• Delete a Pod: Deleting a Pod managed by a Deployment causes the controller to recreate it to satisfy the desired replica count^[400-devops-06-kubernetes-k8s-paas-03k8s.md].
  • kubectl delete [Pod](<./pod.md>) <pod-name> -n <namespace> [--force --grace-period=0]
• Delete a Deployment: Removes the controller and all associated Pods^[400-devops-06-kubernetes-k8s-paas-03k8s.md].
  • kubectl delete deploy <name> -n <namespace>

Service Management¶

Services provide network access to applications by exposing a stable network endpoint^[400-devops-06-kubernetes-k8s-paas-03k8s.md].

• Expose: Creates a Service for a Deployment^[400-devops-06-kubernetes-k8s-paas-03k8s.md].

  [kubectl](<./kubectl.md>) expose deployment <name> --port=<port> -n <namespace>
  

• List: kubectl get svc -n <namespace>

Declarative Management¶

Resources can be managed declaratively using YAML configuration files, which is often referred to as "Resource Configuration" or "Infrastructure as Code"¹.^[400-devops-06-kubernetes-k8s-paas-03k8s.md]

Configuration Files¶

• Get YAML: To generate a template or view the configuration of an existing resource^[400-devops-06-kubernetes-k8s-paas-03k8s.md]: kubectl get <resource> <name> -o yaml -n <namespace>
• Explain: To understand the structure of a specific resource field^[400-devops-06-kubernetes-k8s-paas-03k8s.md]: kubectl explain <resource>.<field>

Apply and Delete¶

• Create/Apply: kubectl apply -f <file.yaml>^[400-devops-06-kubernetes-k8s-paas-03k8s.md]
• Delete: kubectl delete -f <file.yaml>^[400-devops-06-kubernetes-k8s-paas-03k8s.md]

Editing¶

Resources can be modified "online" (live) or "offline" (via the config file)^[400-devops-06-kubernetes-k8s-paas-03k8s.md]. * Online: kubectl edit svc <name> opens the live configuration in an editor^[400-devops-06-kubernetes-k8s-paas-03k8s.md].

Interaction and Debugging¶

• Exec: Execute commands inside a container^[400-devops-06-kubernetes-k8s-paas-03k8s.md].

  [kubectl](<./kubectl.md>) exec -ti <pod-name> /bin/bash -n <namespace>
  

  • -t: Allocates a pseudo-TTY.
  • -i: Passes STDIN to the container.
• Logs: Print the logs for a container^[400-devops-06-kubernetes-k8s-paas-03k8s.md]. kubectl logs -f <pod-name>
• Describe: View detailed state of a resource^[400-devops-06-kubernetes-k8s-paas-03k8s.md]. kubectl describe deployment <name> -n <namespace>

Sources¶

^[400-devops-06-kubernetes-k8s-paas-03k8s.md]