Pod
Table of contents
Pod 에 관해 설명한다.
Pod 생명 주기
[Pod 및 컨테이너 ]
Pod 란 콩깍지라는 어원으로 어플리케이션 기본 실행 단위(컨테이너) 를 배포할 수 있는 가장 작은 단위를 말한다. 즉, 하나의 컨테이너 또는 그를 보조하는 컨테이너까지 포함하여 이를 Pod 라고 일컫는다.
- Pending
- Running
- Succeeded
- Failed
- Unknown
Pod 생성하기
Pod 관련 조회
kubectl get pods
pod 조회한다.
kubectl describe pod [app]
상세 조회
kubectl delete pod --all
모든 파드를 삭제
명령으로 Pod 생성
kubectl run app --image takytaky/app:v1
kubectl delete pod app
root@master:~# kubectl delete pod app
^[[A^[[5~pod "app" deleted
root@master:~# kubectl run app --image takytaky/app:v1
pod/app created
root@master:~# kubectl describe pod app
YAML 파일 사용하여 Pod 생성
yaml 파일 설정은 아래와 같은 때를 예로 한다.
root@master:~/labfile/pod# cat app.yaml
apiVersion: v1
kind: Pod
metadata:
name: app // 파드의 이름(Namespace 에서 유일한 식별정보)
labels:
app: webapp // 오브젝트를 식별하는 라벨(유일 X)
spec:
containers:
- image: takytaky/app:v1 // 컨테이너에 사용할 이미지
name: app-container
ports:
- containerPort: 80 // 컨테이너에 접속할 포트 번호
protocol: TCP
root@master:~/labfile/pod#
kubectl apply -f app.yaml
Pod 생성 명령어를 입력한다.
root@master:~/labfile/pod# kubectl apply -f app.yaml
pod/app created
root@master:~/labfile/pod#
// 확인
root@master:~/labfile/pod# kubectl get pods
NAME READY STATUS RESTARTS AGE
app 1/1 Running 0 17s
root@master:~/labfile/pod#
kubectl delete -f app.yaml
root@master:~/labfile/pod# kubectl delete -f app.yaml
pod “app” deleted
Pod 리소스 할당
CPU
root@master:~/labfile/pod/pod-resources# cat cpu-request-limit.yaml
apiVersion: v1
kind: Pod
metadata:
name: cpu-demo
namespace: cpu-example
spec:
containers:
- name: cpu-demo-ctr
image: vish/stress
resources:
limits:
cpu: "1"
requests:
cpu: "0.5"
args:
- -cpus
- "2"
root@master:~/labfile/pod/pod-resources#
root@master:~/labfile/pod/pod-resources# kubectl create namespace cpu-example
namespace/cpu-example created
root@master:~/labfile/pod/pod-resources# kubectl get ns
NAME STATUS AGE
cpu-example Active 5s
default Active 43h
kube-node-lease Active 43h
kube-public Active 43h
kube-system Active 43h
root@master:~/labfile/pod/pod-resources# kubectl apply -f cpu-request-limit.yaml
pod/cpu-demo created
worker1 에 생성됨
Every 1.0s: kubectl get pods -o wide -n cpu-example master: Sat Jan 14 08:33:37 2023
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
cpu-demo 1/1 Running 0 2m46s 172.16.235.131 worker1 <none> <none>
worker1 에서 docker stats 실시간 자원 사용량 조회
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
f82cf3210728 k8s_cpu-demo-ctr_cpu-demo_cpu-example_01bcc06c-4fb9-4d41-9ec0-8ed06f9a8f45_0 97.67% 1.191MiB / 3.852GiB 0.03% 0B / 0B 0B / 0B 5
7c06002bc43e k8s_POD_cpu-demo_cpu-example_01bcc06c-4fb9-4d41-9ec0-8ed06f9a8f45_0 0.00% 564KiB / 3.852GiB 0.01% 0B / 0B 0B / 0B 1
b2938116ec2a k8s_calico-node_calico-node-ndnrd_kube-system_8f163faa-d00f-4ed4-8a43-70239433078b_2 2.20% 93.87MiB / 3.852GiB 2.38% 0B / 0B 30.5MB / 233kB 64
db016fb7b959 k8s_kube-proxy_kube-proxy-rvdnm_kube-system_b0fd824c-953a-4014-8397-419a58d57d6c_2 0.00% 16.69MiB / 3.852GiB 0.42% 0B / 0B 44MB / 12.3kB 7
2d58d5594367 k8s_POD_calico-node-ndnrd_kube-system_8f163faa-d00f-4ed4-8a43-70239433078b_2 0.00% 1.312MiB / 3.852GiB 0.03% 0B / 0B 627kB / 0B 1
6b4b7d59384d k8s_POD_kube-proxy-rvdnm_kube-system_b0fd824c-953a-4014-8397-419a58d57d6c_2 0.00% 740KiB / 3.852GiB 0.02% 0B / 0B 0B / 0B 1
Memory
root@master:~/labfile/pod/pod-resources# cat memory-request-limit.yaml
apiVersion: v1
kind: Pod
metadata:
name: memory-demo
namespace: mem-example
spec:
containers:
- name: memory-demo-ctr
image: polinux/stress
resources:
limits:
memory: "200Mi"
requests:
memory: "100Mi"
command: ["stress"]
args: ["--vm", "1", "--vm-bytes", "150M", "--vm-hang", "1"]
root@master:~/labfile/pod/pod-resources#
// NS 생성
root@master:~/labfile/pod/pod-resources# kubectl create ns mem-example
namespace/mem-example created
root@master:~/labfile/pod/pod-resources# kubectl get ns
NAME STATUS AGE
default Active 43h
kube-node-lease Active 43h
kube-public Active 43h
kube-system Active 43h
mem-example Active 4s
// 컨테이너 생성
root@master:~/labfile/pod/pod-resources# kubectl apply -f memory-request-limit.yaml
pod/memory-demo created
root@master:~/labfile/pod/pod-resources#
root@master:~/labfile/pod/pod-resources#
컨테이너 생성 확인한다.
Every 1.0s: kubectl get pods -o wide -n mem-example master: Sat Jan 14 08:39:18 2023
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
memory-demo 1/1 Running 0 2m43s 172.16.189.69 worker2 <none> <none>
worker2 에서 메모리 사용량 확인한다.
root@worker2:~# docker stats --no-stream
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
373dff622661 k8s_memory-demo-ctr_memory-demo_mem-example_4a24635a-760d-4e8b-93f1-db0d45f4f7a8_0 15.75% 151.1MiB / 200MiB 75.54% 0B / 0B 0B / 0B 2
38ce1f8aecee k8s_POD_memory-demo_mem-example_4a24635a-760d-4e8b-93f1-db0d45f4f7a8_0 0.00% 628KiB / 3.852GiB 0.02% 0B / 0B 0B / 0B 1
8479dcbb9470 k8s_calico-node_calico-node-s99pf_kube-system_640bad34-5dc5-4c64-91cb-5b21aeee4dce_1 2.07% 91.51MiB / 3.852GiB 2.32% 0B / 0B 29.2MB / 233kB 63
ee914529a024 k8s_kube-proxy_kube-proxy-cbkjv_kube-system_ad42f097-9ee0-4659-b46f-d01757439edd_2 0.00% 16.6MiB / 3.852GiB 0.42% 0B / 0B 44MB / 12.3kB 7
db632c6cc766 k8s_POD_calico-node-s99pf_kube-system_640bad34-5dc5-4c64-91cb-5b21aeee4dce_2 0.00% 760KiB / 3.852GiB 0.02% 0B / 0B 0B / 0B 1
47f87181b42e k8s_POD_kube-proxy-cbkjv_kube-system_ad42f097-9ee0-4659-b46f-d01757439edd_2 0.00% 1.305MiB / 3.852GiB 0.03% 0B / 0B 627kB / 0B 1
root@worker2:~#
initContainer (초기화 컨테이너)
컨테이너가 실행되기 전에 파드를 초기화 할 목적으로 사용된다.
[초기화 컨테이너 예시]
root@master:~/labfile/pod# cat init-containers.yaml
apiVersion: v1
kind: Pod
metadata:
name: init-demo
spec:
containers:
- name: nginx
image: nginx
ports:
- containerPort: 80
volumeMounts:
- name: workdir
mountPath: /usr/share/nginx/html
# These containers are run during pod initialization
initContainers:
- name: install
image: busybox
command:
- wget
- "-O"
- "/work-dir/index.html"
- http://info.cern.ch
volumeMounts:
- name: workdir
mountPath: "/work-dir"
dnsPolicy: Default
volumes:
- name: workdir
emptyDir: {}
root@master:~/labfile/pod# kubectl apply -f init-containers.yaml
pod/init-demo created
root@master:~/labfile/pod#
root@master:~/labfile/pod# curl -sf http://172.16.235.132
<html><head></head><body><header>
<title>http://info.cern.ch</title>
</header>
<h1>http://info.cern.ch - home of the first website</h1>
<p>From here you can:</p>
<ul>
<li><a href="http://info.cern.ch/hypertext/WWW/TheProject.html">Browse the first website</a></li>
<li><a href="http://line-mode.cern.ch/www/hypertext/WWW/TheProject.html">Browse the first website using the line-mode browser simulator</a></li>
<li><a href="http://home.web.cern.ch/topics/birth-web">Learn about the birth of the web</a></li>
<li><a href="http://home.web.cern.ch/about">Learn about CERN, the physics laboratory where the web was born</a></li>
</ul>
</body></html>
Static Pod (스태틱 파드)
apiserver 를 통하지 않고, kubelet 이 직접 실행하는 파드이며, 기본 경로는 /etc/kubernetes/manifests 이다.
root@master:~/labfile/pod# cd /etc/kubernetes/manifests
root@master:/etc/kubernetes/manifests# ll
total 24
drwxr-xr-x 2 root root 4096 Jan 12 13:29 ./
drwxr-xr-x 4 root root 4096 Jan 14 07:35 ../
-rw------- 1 root root 2195 Jan 12 13:29 etcd.yaml
-rw------- 1 root root 3978 Jan 12 13:29 kube-apiserver.yaml
-rw------- 1 root root 3351 Jan 12 13:29 kube-controller-manager.yaml
-rw------- 1 root root 1385 Jan 12 13:29 kube-scheduler.yaml
master 시작 시 kubelet 데몬 실행에서 위 static pod 가 실행된다.