my-cka-journey

Prepare your exam

• Certified Kubernetes Administrator (CKA) - A Cloud Guru
• Certified Kubernetes Administrator (CKA) with Practice Tests - Udemy
• Do 2–3 times the following CKAD-exercises
• Do the CKAD series with scenarios on Medium
• Do the CKA series with scenarios
• Do the chadmcrowell/CKA-Exercises
• Do the moabukar/CKA-Exercises
• Do the alijahnas/CKA-practice-exercises
• Do the Certified Kubernetes Administrator (CKA) Crash Course

Exam tips

1. Set the following before starting the examn:

   alias k=kubectl                         # will already be pre-configured
   export do="--dry-run=client -o yaml"    # k get pod x $do
   export now="--force --grace-period 0"   # k delete pod x $now

2. Create the file ~/.vimrc with the following content:

   set tabstop=2
   set expandtab
   set shiftwidth=2

3. Open 2 tabs with the following:

   • Cheatsheet
   • Kubernetes Official Documentation index

4. When you have to fix a component (like kubelet) in one cluster, just check how its setup on another node in the same or even another cluster. You can copy config files over etc.

Vim tips

• :set number followed by Enter to toggle line numbers
• :set paste to paste fromated yaml
• Copy&paste
  • Mark lines: Esc+V (then arrow keys)
  • Copy marked lines: y
  • Cut marked lines: d
  • Past lines: p or P

Fast commands

• Get pod base yaml: k -n namespace run p2-pod --image=nginx:1.21.3-alpine $do > p2-pod.yaml
• Get pod labels: k -n namespace get pod -L app
• Create service pod: k -n namespace expose pod p2-pod --name p2-service --port 3000 --target-port 80
• Filter by labels: k get svc,ep -l app=check-ip

Important paths & config files

• /etc/systemd/system/kubelet.service.d/10-kubeadm.conf: Kubelete config file
• /etc/kubernetes/pki: Certificates
• cat /etc/kubernetes/manifests/kube-apiserver.yaml | grep etcd: Check etcd config
• Change CIDR -> /etc/kubernetes/manifests/kube-apiserver.yaml and /etc/kubernetes/manifests/kube-controller-manager.yaml (at --service-cluster-ip-range)

Usefull stuff

Schedule pods in Control Plane nodes (tolerations)

spec:
  tolerations:                            
  - effect: NoSchedule                    
    key: node-role.kubernetes.io/master   

Confirm k8s services are running

• crictl ps | grep kube-proxy

• iptables-save | grep p2-service