Post

K8s

Posted Updated
By komidawi
1 min read
K8s

Knowledge, commands, parameters and everything relevant when using Kubernetes (K8s).

Simple commands

  1. View logs since
    1. Given timestamp
      • k logs --since-time='2023-05-14T00:00:00Z' <pod_name>
    2. Last n hours
      • k logs --since=24h <pod_name>
    3. Last n lines
      • k logs --tail=100 <pod_name>
  2. Get password from deployment secrets
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       k get deployments -> k describe deployment my-deployment
 k get secret db-password -o yaml
 echo <thepassword> | base64 -d
    • k describe secret <secret>
  3. Switch namespace
    • k config set-context --current --namespace=dev
  4. Show config (namespace etc.)
    • k config view
  5. Print only namespace
    • k config view --minify --output 'jsonpath={..namespace}'; echo
  6. Show deployment details
    • k describe deployment <deployment>
  7. Show information about pod (e.g. latest failures)
    • k descripe pod <pod>

Merge multiple config files

Automatically

Assuming:

  • you have config-one and config-two in ~./kube directory
  • values within files won’t conflict (override) each other
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export KUBECONFIG=~/.kube/config-one:~/.kube/config-two
kubectl config view
kubectl config view --flatten
kubectl config view --flatten > common.yaml

Manually

Sometimes it’s just easier and faster to follow the template below:

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apiVersion: v1
kind: Config
preferences: { }
current-context: k8s-old
contexts:
    -   context:
            cluster: k8s-old-cluster
            user: k8s-old-admin
            namespace: my-old-app
        name: k8s-old
    -   context:
            cluster: k8s-new-cluster
            user: k8s-new-admin
            namespace: my-new-app
        name: k8s-new
clusters:
    -   cluster:
            certificate-authority-data: tomato1
            server: https://1.2.3.4:1234
        name: k8s-old-cluster
    -   cluster:
            certificate-authority-data: tomato2
            server: https://4.3.2.1:4321
        name: k8s-new-cluster
users:
    -   name: k8s-old-admin
        user:
            client-certificate-data: tomato3
            client-key-data: tomato4
    -   name: k8s-new-admin
        user:
            client-certificate-data: tomato5
            client-key-data: tomato6
devops
k8s kubernetes