Kubernetes_3

2023.01.31

5장 pod

---

실습 1

• workspace 만들기

mkdir workspace
cd workspace

💦 app.js 및 dockerfile 생성

cat > app.js

const http = require(‘http’);
const os = require(‘os’);
console.log(“Test Server starting!!!”);
var handler = function(req, res) {
  res.writeHead(200);
  res.end(“Container Hostname:” + os.hostname() + “\n”);
};
var www = http.createServer(handler);
www..listen(8080);

cat > dockerfile

FROM node:12
COPY app.js /app.js
ENTRYPOINT [“node”, “app.js”]

💦 docker 이미지 생성 및 push

💨 docker에 로그인
sudo -i docker login

💨 도커파일 빌드
docker build -t smlinux/appjs .

💨 빌드된 이미지 푸쉬
docker push smlinux/appjs

docker 권한 문제(Permission denied)

💨 docker 그룹 생성 (이미 있을 수 있음)
sudo groupadd docker

💨 그룹에 docker 권한 추가
sudo usermod -aG docker $USER

💨 나갔다 들어와서 id 확인(docker 추가 됐는지)
exit
id

💦 생성한 이미지 pod로(docker hub가 안돼서 이대로 했음...)

kubectl run webserver --image=nginx:1.14

kubectl get pods

💦 생성한 pod를 yaml파일로 받아서 커스터마이징

kubectl run webserver --image=nginx:1.14 --dry-run -o yaml > pod-nginx.yaml

vim pod-nginx.yaml
----------------------------------------------------
apiVersion: v1
kind: Pod
metadata:
  name: webserver
spec:
  containers:
  - image: nginx:1.14
    name: nginx-container
    ports:
    - containerPort: 80
      protocol: TCP
      

💦 생성한 pod를 지우고 yaml파일로 새로운 pod 생성

kubectl delete pod webserver

kubectl apply -f pod-nginx.yaml

kubectl describe pod webserver

curl [ip주소]

---

실습 2 : 멀티파드

💦 yaml 파일 생성

cat > pod-multi.yaml

apiVersion: v1
kind: Pod
metadata:
  name: multipod
spec:
  containers:
  - name: nginx-container
    image: nginx:1.14
    ports:
    - containerPort: 80
  - name: centos-container
    image: centos:7
    command:
    - sleep
    - "10000"

💨 pod 생성
kubectl apply -f pod-multi.yaml

💨 실행되는 pod 안으로 들어가기
kubectl exec multipod -it -c centos-container -- /bin/bash

💨 안으로 들어와서 확인
ps -ef
------------------------------------------------------
UID          PID    PPID  C STIME TTY          TIME CMD
root           1       0  0 02:03 ?        00:00:00 sleep 10000
root           7       0  0 02:06 pts/0    00:00:00 /bin/bash
root          23       7  0 02:06 pts/0    00:00:00 ps -ef
------------------------------------------------------

💨 잘 돌아가는지 확인
curl http://localhost:80

exit

💨 log 확인 
kubectl logs multipod -c nginx-container
kubectl logs multipod -c centos-container

💨 실행되는 pod의 내용 수정
kubectl edit pod multipod

kubectl delete pod multipod

---

실습 3: 컨테이너의 상태를 점검할 수 있는 liveness

💦 yaml 파일 만들기

cp pod-nginx.yaml pod-nginx-liveness.yaml

vim pod-nginx-liveness.yaml
--------------------------------------------
apiVersion: v1
kind: Pod
metadata:
  name: nginx-liveness
spec:
  containers:
  - image: nginx:1.14
    name: nginx-container
    ports:
    - containerPort: 80
      protocol: TCP
    livenessProbe:
      httpGet:
        path: /
        port: 80

kubectl apply -f pod-nginx-liveness.yaml

++ 추가: 설정 바꿔주기

cp pod-nginx-liveness.yaml pod-nginx-livenessProbe.yaml

vim pod-nginx-livenessProbe.yaml
------------------------------------------------------------
apiVersion: v1
kind: Pod
metadata:
  name: nginx-liveness-modified
spec:
  containers:
  - image: nginx:1.14
    name: nginx-container
    ports:
    - containerPort: 80
      protocol: TCP
    livenessProbe:
      httpGet:
        path: /
        port: 80
      initialDelaySeconds: 15
      periodSeconds: 20
      timeoutSeconds: 1
      successThreshold: 1
      failureThreshold: 3

&& kubectl edit pod nginx-liveness 명령어를 통해서도 수정이 가능하다

---

실습 4: busybox

💦 yaml 파일 생성

cat > liveness-exam.yaml
-------------------------------------------------
apiVersion: v1
kind: Pod
metadata:
  name: liveness-exam
spec:
  containers:
  - name: busybox-container
    image: busybox
    args:
    - /bin/sh
    - -c
    - touch /tmp/healthy; sleep 30; rm -rf /tmp/healthy; sleep 600
    livenessProbe:
      exec:
        command:
        - ls
        - /tmp/healthy
      initialDelaySeconds: 10
      periodSeconds: 10
      successThreshold: 1

💦 실행

kubectl apply -f liveness-exam.yaml

watch kubectl get pods -o wide
명령어를 통해 restart 되는 것을 확인하기

---

실습 5: init

💦 yaml 파일 생성

cat > init-container-exam.yaml
----------------------------------------------------------------
apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
spec:
  containers:
  - name: myapp-container
    image: busybox:1.28
    command: ['sh', '-c', 'echo The app is running! && sleep 3600']
  initContainers:
  - name: init-myservice
    image: busybox:1.28
    command: ['sh', '-c', "until nslookup myservice.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local; do echo waiting for myservice; sleep 2; done"]
  - name: init-mydb
    image: busybox:1.28
    command: ['sh', '-c', "until nslookup mydb.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local; do echo waiting for mydb; sleep 2; done"]

💦 실행

kubectl apply -f init-container-exam.yaml

watch kubectl get pods -o wide
💨 명령어를 통해 status가 initialize 대기중인지 확인
(init 대기중임..!)

cat > init-container-exam-svc.yaml
-------------------------------------
apiVersion: v1
kind: Service
metadata:
  name: myservice
spec:
  ports:
  - protocol: TCP
    port: 80
    targetPort: 9376
   
   
cat > init-container-exam-mydb.yaml
-----------------------------------------
apiVersion: v1
kind: Service
metadata:
  name: mydb
spec:
  ports:
  - protocol: TCP
    port: 80
    targetPort: 9377

kubectl apply -f init-container-exam-svc.yaml
kubectl apply -f init-container-exam-mydb.yaml

이후 잘 실행되는지 확인!

---

실습 6: infra container

...?

실습 7: static container

work-node에서 /etc/kubernetes/manifests로 접근.

vi /var/lib/kubelet/config.yaml에서 staticPodPath의 경로 확인

web.yaml
----------------------------------------
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: web
  name: web
spec:
  containers:
  - image: nginx:1.14
    name: web
    ports:
    - containerPort: 80

web-node1 이라는 이름으로 pod 생성
cp web.yaml /etc/kubernetes/manifests/

pod 삭제
rm /etc/kubernetes/manifests/web.yam

실습 8: pod resource

💦 yaml 파일 생성

cat > pod-resource.yaml

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod-env
spec:
  containers:
  - name: nginx-container
    image: nginx:1.14
    ports:
    - containerPort: 80
      protocol: TCP
    resources:
      requests:
        memory: 500Mi
        cpu: 200m
      limits:
        memory: 1Gi
        cpu: 1

💦 실행 및 확인

kubectl apply -f pod-resource.yaml

💨 container 부분 확인해보기
kubectl describe pod nginx-pod-env

실습 9: 환경변수

💦 yaml 파일 생성

cat > pod-nginx-env.yaml
--------------------------------------
apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod-env
spec:
  containers:
  - name: nginx-container
    image: nginx:1.14
    ports:
    - containerPort: 80
      protocol: TCP
    env:
    - name: MYVAR
      value: "testvalue"

💦 실행 및 확인

kubectl apply -f pod-nginx-env.yaml

kubectl exec nginx-pod-env -- env
-----------------------------------------------------------------------
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=nginx-pod-env
NGINX_VERSION=1.14.2-1~stretch
NJS_VERSION=1.14.2.0.2.6-1~stretch
MYVAR=testvalue
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
KUBERNETES_SERVICE_HOST=10.96.0.1
KUBERNETES_SERVICE_PORT=443
KUBERNETES_SERVICE_PORT_HTTPS=443
HOME=/root

pod 구성 실행패턴

sidecar
adapter
ambassador