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- 용어 정리
(1) kubeadm: 클러스터를 부트스트랩 하는 명령어
- bootstrap: 클러스터를 처음부터 생성하고 실행
(2) kubelet: 클러스터의 모든 머신에서 실행되는 파드와 컨테이너 시작과 같은 작업을 수행하는 컴포넌트
(3) kubectl: 클러스터와 통신하기 위한 커맨드 라인 유틸리
- kubectl [command] [type] [name] [flags]
- command: 실행하려는 동작으로 create, get, delete 등을 사용
- type: 자원 타입. pod, service, ingress 등을 사용
- name: 자원 이름
- flag: 부가적으로 설정할 옵션을 입력
## node 확인
$ kubectl get nodes
## node 상세 조회
$ kubectl get nodes -o wide
## pod 조회 (구성 초기에는 별도로 생성한 pod가 없어서 나오지 않음)
$ kubectl get pods
## pod 조회 (namespaces 전체)
$ kubectl get pod --all-namepaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-787d4945fb-frc8t 1/1 Running 1 (20m ago) 4d17h
kube-system coredns-787d4945fb-mxdk6 1/1 Running 1 (20m ago) 4d17h
kube-system etcd-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-system kube-apiserver-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-system kube-controller-manager-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-system kube-proxy-j9mlk 1/1 Running 1 (20m ago) 2d19h
kube-system kube-proxy-jn7r4 1/1 Running 1 (20m ago) 2d19h
kube-system kube-proxy-s9hj7 1/1 Running 2 (20m ago) 4d17h
kube-system kube-scheduler-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-system weave-net-b8g94 2/2 Running 3 (20m ago) 2d21h
kube-system weave-net-c44x7 2/2 Running 2 (20m ago) 2d19h
kube-system weave-net-s7xvl 2/2 Running 2 (20m ago) 2d19h
## pod 조회 (특정한 namespaces)
$ kubectl get pod -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-787d4945fb-frc8t 1/1 Running 1 (20m ago) 4d17h
coredns-787d4945fb-mxdk6 1/1 Running 1 (20m ago) 4d17h
etcd-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-apiserver-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-controller-manager-k8s-master 1/1 Running 2 (20m ago) 4d17h
kube-proxy-j9mlk 1/1 Running 1 (20m ago) 2d19h
kube-proxy-jn7r4 1/1 Running 1 (20m ago) 2d19h
kube-proxy-s9hj7 1/1 Running 2 (20m ago) 4d17h
kube-scheduler-k8s-master 1/1 Running 2 (20m ago) 4d17h
weave-net-b8g94 2/2 Running 3 (20m ago) 2d21h
weave-net-c44x7 2/2 Running 2 (20m ago) 2d19h
weave-net-s7xvl 2/2 Running 2 (20m ago) 2d19h
- kubectl 기본 사용법
(1) echoserver pod 생성
## echoserver pod 생성(클라이언트가 전송해주는 데이터를 그대로 되돌려 전송하는 서버)
$ kubectl run echoserver --image="k8s.gcr.io/echoserver:1.10" --port=8080
pod/echoserver created
## echoserver service 생성(pod들에 접근할 때 필요)
$ kubectl expose po echoserver --type=NodePort
service/echoserver exposed
## pod 생성 확인
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
echoserver 1/1 Running 0 100s
## pod 상세 정보 확인
$ kubectl describe pods echoserver
Name: echoserver
Namespace: default
Priority: 0
Service Account: default
Node: k8s-worker1/192.168.130.132
Start Time: Mon, 06 Feb 2023 04:48:21 +0000
Labels: run=echoserver
Annotations: <none>
Status: Running
IP: 10.44.0.1
IPs:
IP: 10.44.0.1
Containers:
echoserver:
Container ID: containerd://028d1d880e7ef44bdc6adfed07d8b59ed9b705c50b8792b714e4c69b6eb181ef
Image: k8s.gcr.io/echoserver:1.10
Image ID: k8s.gcr.io/echoserver@sha256:cb5c1bddd1b5665e1867a7fa1b5fa843a47ee433bbb75d4293888b71def53229
Port: 8080/TCP
Host Port: 0/TCP
State: Running
Started: Mon, 06 Feb 2023 04:48:30 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-kkt6n (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-kkt6n:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 68m default-scheduler Successfully assigned default/echoserver to k8s-worker1
Normal Pulling 68m kubelet Pulling image "k8s.gcr.io/echoserver:1.10"
Normal Pulled 68m kubelet Successfully pulled image "k8s.gcr.io/echoserver:1.10" in 7.422212496s (7.422219623s including waiting)
Normal Created 68m kubelet Created container echoserver
Normal Started 68m kubelet Started container echoserver
- name: pod 이름
- ready: 숫자/숫자 형태로 준비 상태 표시, 0/1은 생성되지 않았거나 준비가 되지 않은 상태이고 1/1이면 생성 및 사용할 준비가 끝났다는 뜻
- status: pod 현 상태, running(실행중)/terminating(컨테이너 접속 중)/containercreating(생성중) 등
- restarts: pod 재시작 횟수
- age: pod가 생성된 후 얼마나 시간이 지났는지 표기
## 서비스 확인
$ kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
echoserver NodePort 10.100.132.118 <none> 8080:30552/TCP 7m9s
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 4d21h
- name: 서비스 이름
- type: 서비스 타입
- cluster-ip: 현 클러스터 안에서 사용되는 ip
- external-ip: 외부에서 접속할 때 사용하는 ip, 별도 설정하지 않으면 none으로 표기
- port(s): 서비스에 접속하는 포트
- age: 생성 후 지난 시간
※ kubernetes 서비스는 kube-apiserver 관련 pod들을 가리킴
## echoserver 접속해보기 - 포트포워딩
$ kubectl port-forward svc/echoserver 8080:8080
Forwarding from 127.0.0.1:8080 -> 8080
Forwarding from [::1]:8080 -> 8080
(2) echoserver 확인
$ curl <http://localhost:8080>
Hostname: echoserver
Pod Information:
-no pod information available-
Server values:
server_version=nginx: 1.13.3 - lua: 10008
Request Information:
client_address=127.0.0.1
method=GET
real path=/
query=
request_version=1.1
request_scheme=http
request_uri=http://localhost:8080/
Request Headers:
accept=*/*
host=localhost:8080
user-agent=curl/7.68.0
Request Body:
-no body in request-
## echoserver pod log 확인
$ kubectl logs -f echoserver
Generating self-signed cert
Generating a 2048 bit RSA private key
........................................+++
.....................................................................................................................................................+++
writing new private key to '/certs/privateKey.key'
-----
Starting nginx
127.0.0.1 - - [06/Feb/2023:05:45:57 +0000] "GET / HTTP/1.1" 200 774 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0"
127.0.0.1 - - [06/Feb/2023:05:45:57 +0000] "GET /favicon.ico HTTP/1.1" 200 723 "<http://localhost:8080/>" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0"
127.0.0.1 - - [06/Feb/2023:05:50:14 +0000] "GET / HTTP/1.1" 200 809 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0"
127.0.0.1 - - [06/Feb/2023:05:51:58 +0000] "GET / HTTP/1.1" 200 416 "-" "curl/7.68.0"
(3) nginx webserver pod 생성
## nginx 최신 버전 pod 생성
$ kubectl run webserver --image=nginx:latest --port 80
pod/webserver created
## pod 확인
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
echoserver 1/1 Running 0 67m
webserver 1/1 Running 0 79s
## pod 상세 확인
$ kubectl describe pods webserver
Name: webserver
Namespace: default
Priority: 0
Service Account: default
Node: k8s-worker2/192.168.130.133
Start Time: Mon, 06 Feb 2023 05:54:56 +0000
Labels: run=webserver
Annotations: <none>
Status: Running
IP: 10.36.0.1
IPs:
IP: 10.36.0.1
Containers:
webserver:
Container ID: containerd://985eeeb0259ae152c6dbb3bce9738a85148b4d2f6d9b827a1f0f52033b917838
Image: nginx:latest
Image ID: docker.io/library/nginx@sha256:c54fb26749e49dc2df77c6155e8b5f0f78b781b7f0eadd96ecfabdcdfa5b1ec4
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Mon, 06 Feb 2023 05:55:03 +0000
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-7lcpw (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-7lcpw:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 2m45s default-scheduler Successfully assigned default/webserver to k8s-worker2
Normal Pulling 2m44s kubelet Pulling image "nginx:latest"
Normal Pulled 2m38s kubelet Successfully pulled image "nginx:latest" in 6.495441948s (6.495448359s including waiting)
Normal Created 2m38s kubelet Created container webserver
Normal Started 2m38s kubelet Started container webserver
(4) ngix 확인 - curl, firefox web
$ curl 10.36.0.1
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
(5) pod 및 서비스 삭제
## pod 확인
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
echoserver 1/1 Running 0 73m
webserver 1/1 Running 0 7m
## pod 삭제
$ kubectl delete pod echoserver
pod "echoserver" deleted
$ kubectl delete pod webserver
pod "webserver" deleted
## service 확인
$ kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
echoserver NodePort 10.100.132.118 <none> 8080:30552/TCP 74m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 4d22h
## service 삭제
$ kubectl delete service echoserver
service "echoserver" deleted
## 확인
$ kubectl get pods
No resources found in default namespace.
$ kubectl get service
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 4d22h
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