Kubernetes Basics for Connections Admins

set cursorline          " highlight current line
hi CursorLine   cterm=NONE ctermbg=235 ctermfg=NONE guifg=gray guibg=black
set cursorcolumn        " vertical cursor line
hi CursorColumn ctermfg=NONE ctermbg=235 cterm=NONE guifg=gray guibg=black gui=bold

kubectl run db --image mongo

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
    ports:
    - containerPort: 80

$ kubectl create -f nginx.yaml

$ kubectl get all -o wide

NAME        READY   STATUS    RESTARTS   AGE   IP           NODE
pod/nginx   1/1     Running   0          4m    10.42.1.13   rancher2

...
    - containerPort: 80
    env:
    - name: nginx
      value: localhost
    livenessProbe:
      httpGet:
        path: /              (1)
        port: 80
      initialDelaySeconds: 5 (2)
      timeoutSeconds: 2      (3)
      periodSeconds: 5       (4)
      failureThreshold: 1    (5)

$ kubectl describe nginx-broken

$ kubectl create -f nginx-rs.yaml --record --save-config  (1) (2)

$ kubectl get pods

NAME                  READY   STATUS    RESTARTS   AGE   IP           NODE       NOMINATED NODE
pod/webserver-79r7j   1/1     Running   0          15m   10.42.3.15   rancher3   <none>
pod/webserver-dg5bp   1/1     Running   0          15m   10.42.2.11   rancher4   <none>
pod/webserver-rmkgx   1/1     Running   0          15m   10.42.1.14   rancher2   <none>

NAME                      DESIRED CURRENT READY AGE CONTAINERS IMAGES       SELECTOR
replicaset.apps/webserver 3       3       3     15m nginx      nginx:1.7.9  service=nginx,type=backend

...
spec:
  replicas: 9

$ kubectl apply -f nginx-rs-scaled.yaml

NAME                  READY   STATUS    RESTARTS   AGE   IP           NODE       NOMINATED NODE
pod/webserver-bw259   1/1     Running   0          5m    10.42.1.15   rancher2   <none>
pod/webserver-frcr7   1/1     Running   0          4m    10.42.1.16   rancher2   <none>
pod/webserver-g6zqd   1/1     Running   0          5m    10.42.2.12   rancher4   <none>
...
pod/webserver-p6k7f   1/1     Running   0          4m    10.42.2.13   rancher4   <none>
pod/webserver-wjwfd   1/1     Running   0          5m    10.42.3.16   rancher3   <none>

NAME                      DESIRED CURRENT READY AGE CONTAINERS IMAGES      SELECTOR
replicaset.apps/webserver 9       9       9     5m  nginx      nginx:1.7.9 service=nginx

$  kubectl create -f nginx-deploy.yaml --record
$  kubectl apply -f nginx-deploy-scaled.yaml
$  kubectl scale deployment nginx --replicas 9 --record
$  kubectl scale deployment nginx --replicas 5 --record
$  kubectl rollout history -f nginx-deploy.yaml
$  kubectl set image -f nginx-deploy-scaled.yaml nginx=nginx:1.8.1 --record
$  kubectl rollout history -f nginx-deploy.yaml
$  kubectl rollout undo -f nginx-deploy-scaled.yaml --to-revision=1

apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  type: NodePort  (1)
  ports:
  - port: 80
    nodePort: 30001 (2)
    protocol: TCP
  selector:
    service: nginx

$ kubectl scale deployment nginx --replicas 1 --record

for i in 2 3 4
do
    curl -s http://rancher$i.stoepslab.local | grep title
done
<title>Welcome to nginx!</title>
<title>Welcome to nginx!</title>
<title>Welcome to nginx!</title>

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: my-ingress
spec:
  rules:
  - host: www.stoepslab.local
    http:
      paths:
      - backend:
          serviceName: nginx
          servicePort: 80

    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        volumeMounts:
          - name: nginx-soccnx
            mountPath: /usr/share/nginx/html
      volumes:
        - name: nginx-soccnx
          configMap:
            name: nginx-soccnx

apiVersion: v1
   kind: ConfigMap
   metadata:
     name: special-config
     namespace: default
   data:
     SPECIAL_LEVEL: very
     SPECIAL_TYPE: charm

spec:
     containers:
       - name: nginx-soccnx
         image: alpine:latest
         command: [ "/bin/sh", "-c", "env" ]
         envFrom:
         - configMapRef:
             name: special-config

...
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/
SHLVL=1
SPECIAL_LEVEL=very
SPECIAL_TYPE=charm

$ kubectl create secret generic db-user-pass \
  --from-literal=username=dbadmin \
  --from-literal=password=MyGreatPassword
secret 'db-user-pass' created

$ kubectl create secret generic db-user-env \
  --from-env-file=password.txt

username=dbadmin
password=myGreatPassword

➜ kubectl get secret db-user-env -o yaml
apiVersion: v1
data:
  password: TXlHcmVhdFBhc3N3b3Jk
  username: ZGJhZG1pbg==
kind: Secret

➜ kubectl get secret db-user-env -o jsonpath="{.data.password}" | base64 --decode
MyGreatPassword%

volumes:
- name: db-creds
    secret:
      secretName: db-user-env
      defaultMode: 0444
      items:
      - key: username
        path: username
      - key: password
        path: password

$ kubectl exec -it <pod> -- sh

curl http://nginx.texting:8080
curl http://nginx.production:8080

$ kubectl create namespace soccnx

$ kubectl config set-context soccnx --namespace soccnx \
  --cluster rancher-cluster --user admin

$ kubectl config view

$ kubectl config use-context soccnx

➜ helm search elastic

➜ helm install stable/kibana

kubectl logs <podname> -c <containername>

kubectl logs --previous ${POD_NAME} ${CONTAINER_NAME}

# Single container pod
kubectl exec -it shell-demo -- /bin/bash

# Pod with multiple containers
kubectl exec -it my-pod --container main-app -- /bin/bash