1. Control Plane

1.1. ETCD Backup&Restore

] ssh k8s-master
] etcd --version
] etcdctl version

snapshot using etcdctl options

] sudo ETCDCTL_API=3 etcdctl \
  --endpoints=https://127.0.0.1:2379 \
  --cacert=<trusted-ca-file> \
  --cert=<cert-file> --key=<key-file> \
  snapshot save <backup-file-location>
Snapshot saved at <backup-file-location>

restoring an etcd cluster

] sudo ETCDCTL_API=3 etcdctl snapshot restore \
  --data-dir <new-data-dir-location> <backup-file-location>

] sudo vi /etc/kubernetes/manifests/etcd.yaml
volumes:
  - hostPath:
    path: /var/lib/<new-data-dir-location> # edit
] sudo docker ps -a | grep etcd

2. Worker Node

2.1. Creating Pod

] kubectl create namespace ecommerce
] kubectl -n ecommerce run eshop-main --image=nginx:1.17 --env=DB=mysql

2.2. Creating Static Pod

Static Pod : directly access to kubelet in worker node without control plane API

yaml code extraction for web-pod

] kubectl -n ecommerce run web --image=nginx:1.17 -o yaml

save ouptut

] ssh hk8s-w1
] sudo -i # root mode
] cat /var/lib/kubelet/config.yaml
staticPodPath: /etc/kubernetes/manifests
] cd /etc/kubernetes/manifests
] cat > web-pod.yaml
add saved output in the above step
] exit
] kubectl get pods # check the static pod

2.3. Creating Multi-container Pod

] kubectl run lab004 --image=nginx --dry-run=client -o yaml
] cat > multi.yaml
spec:
  containers:
  - image: nginx
    name: nginx
  - image: redis
    name: redis
  - image: memcached
    name: memcached
] kubectl apply -f multi.yaml
] kubectl describe pod lab004

2.4. Creating Sidecar container

Sidecar Container: built-in logging architecture
1) log /var/log/html in nginx container (main container)
2) store the log to a separated volume in /varlog
3) access /varlog in side-car container(log analyzing purpose)

] kubectl get pod eshop-cart-app # main container
] kubectl get pod eshop-cart-app -o yaml > eshop.yaml

sidecar container with logging agent

] vi eshop.yaml
spec:
  containers:
  - command:
    - /bin/sh
    - -c
    - 'i=1;while :;do  echo -e "$i: Price: $((RANDOM % 10000 + 1))" >> /var/log/cart-app.log;i=$((i+1)); sleep 2; done'
    image: busybox
    name: cart-app
    volumeMounts:
    - mountPath: /var/log
      name: varlog
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
  - name: sidecar
    image: busybox
    args: [/bin/sh, -c, 'tail -n+1 -F /var/log/cart-app.log']
    volumeMounts:
    - name: varlog
      mountPath: /var/log
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
  volumes:
  - emptyDir: {}
    name: varlog

] kubectl delete pod eshop-cart-app # (--force)
] kubectl apply -f eshop.yaml
] kubectl logs eshop-cart-app -c sidecar

2.5. Deployment & Pod Scale

scale reference docs

Pod scale out

] kubectl -n devops get pod deployments.apps
] kubectl -n devops scale deployment eshop-order --replicas=5
] kubectl -n devops get deploy

create and scale out deployment

] kubectl create deployment webserver --image=nginx:1.14 --replicas=2 --dry-run=client -o yaml > webserver.yaml
] vi webserver.yaml
spec:
  replicas: 2
  selector:
    matchLabels:
      app_env_stage=dev
  template:
    metadata:
      labels:
        app_env_stage=dev
    spec:
      containers:
      - image: nginx:1.14
        name: webserver
        ports:
        - containerPort: 80
] kubectl apply -f webserver.yaml
] kubectl get deployments.apps -o wide

] kubectl scale deployment webserver --replicas=3
] kubectl get pods --show-labels