[CKA][실습] 2. Scheduling (2)

Practice Test - Node Affinity

alias k=kubectl
# node01의 라벨 확인
k get no node01 --show-labels=true
k label no node01 color=blue

k create deploy blue --image=nginx --replicas=3 --dry-run=client -o yaml > blue.yaml
k apply -f blue.yaml

• node01에만 배포되는 nodeaffinity 설정

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: blue
  name: blue
spec:
  replicas: 3
  selector:
    matchLabels:
      app: blue
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: blue
    spec:
      containers:
      - image: nginx
        name: nginx
        resources: {}
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: color
                operator: In
                values:
                - blue
status: {}

k replace -f blue.yaml

• node-role.kubernetes.io/control-plane label이 존재하는 node에 배치하는 affinity 설정

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: red
  name: red
spec:
  replicas: 2
  selector:
    matchLabels:
      app: red
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: red
    spec:
      containers:
      - image: nginx
        name: nginx
        resources: {}
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: node-role.kubernetes.io/control-plane
                operator: Exists
status: {}

 

Practice Test - Resource Limits

k get po elephant -o yaml > elephant.yaml
## cpu limit 수정 후 pod 교체
k replace -f elephant.yaml --force=true

Practice Test - DaemonSets

apiVersion: apps/v1
kind: DaemonSet
metadata:
  annotations:
  name: elasticsearch
  namespace: kube-system
spec:
  selector:
    matchLabels:
      app: FluentD
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: FluentD
    spec:
      containers:
        - name: elasticsearch
          image: registry.k8s.io/fluentd-elasticsearch:1.20

Practice Test - Stateful Pod

$ ps -ef | grep kubelet
root        2766    2225  0 00:48 ?        00:00:45 kube-apiserver --advertise-address=192.223.93.9 --allow-privileged=true --authorization-mode=Node,RBAC --client-ca-file=/etc/kubernetes/pki/ca.crt --enable-admission-plugins=NodeRestriction --enable-bootstrap-token-auth=true --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt --etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt --etcd-keyfile=/etc/kubernetes/pki/apiserver-etcd-client.key --etcd-servers=https://127.0.0.1:2379 --kubelet-client-certificate=/etc/kubernetes/pki/apiserver-kubelet-client.crt --kubelet-client-key=/etc/kubernetes/pki/apiserver-kubelet-client.key --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname --proxy-client-cert-file=/etc/kubernetes/pki/front-proxy-client.crt --proxy-client-key-file=/etc/kubernetes/pki/front-proxy-client.key --requestheader-allowed-names=front-proxy-client --requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt --requestheader-extra-headers-prefix=X-Remote-Extra- --requestheader-group-headers=X-Remote-Group --requestheader-username-headers=X-Remote-User --secure-port=6443 --service-account-issuer=https://kubernetes.default.svc.cluster.local --service-account-key-file=/etc/kubernetes/pki/sa.pub --service-account-signing-key-file=/etc/kubernetes/pki/sa.key --service-cluster-ip-range=10.96.0.0/12 --tls-cert-file=/etc/kubernetes/pki/apiserver.crt --tls-private-key-file=/etc/kubernetes/pki/apiserver.key
root        3711       1  0 00:48 ?        00:00:21 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/config.yaml --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock --pod-infra-container-image=registry.k8s.io/pause:3.9
root        8491    7810  0 01:02 pts/0    00:00:00 grep kubelet

$ cat /var/lib/kubelet/config.yaml | grep -i static
staticPodPath: /etc/kubernetes/manifests

$ ls /etc/kubernetes/manifests
etcd.yaml  kube-apiserver.yaml  kube-controller-manager.yaml  kube-scheduler.yaml

$ k run static-busybox --image=busybox --dry-run=client -o yaml --command -- sleep 1000 >> /etc/kubernetes/manifests/static-busybox.yaml

$ k get po -o wide
NAME                          READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
static-busybox-controlplane   1/1     Running   0          35s   10.244.0.5   controlplane   <none>           <none>
static-greenbox-node01        1/1     Running   0          15s   10.244.1.3   node01         <none>           <none>

$ ssh node01
root@node01 ~ ➜  ps -ef | grep kubelet
root        6249       1  0 01:08 ?        00:00:01 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/config.yaml --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock --pod-infra-container-image=registry.k8s.io/pause:3.9
root        6923    6849  0 01:09 pts/0    00:00:00 grep kubelet

root@node01 ~ ➜  cat /var/lib/kubelet/config.yaml | grep -i static
staticPodPath: /etc/just-to-mess-with-you

root@node01 ~ ➜  cd /etc/just-to-mess-with-you

root@node01 /etc/just-to-mess-with-you ➜  ls
greenbox.yaml

root@node01 /etc/just-to-mess-with-you ➜  rm greenbox.yaml

 

Practice Test - Multiple Schedulers

• 새로운 scheduler 추가
• 참고 자료 : https://kubernetes.io/ko/docs/tasks/extend-kubernetes/configure-multiple-schedulers/

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: my-scheduler
  name: my-scheduler
  namespace: kube-system
spec:
  serviceAccountName: my-scheduler
  containers:
  - command:
    - /usr/local/bin/kube-scheduler
    - --config=/etc/kubernetes/my-scheduler/my-scheduler-config.yaml
    image: registry.k8s.io/kube-scheduler:v1.26.0
    livenessProbe:
      httpGet:
        path: /healthz
        port: 10259
        scheme: HTTPS
      initialDelaySeconds: 15
    name: kube-second-scheduler
    readinessProbe:
      httpGet:
        path: /healthz
        port: 10259
        scheme: HTTPS
    resources:
      requests:
        cpu: '0.1'
    securityContext:
      privileged: false
    volumeMounts:
      - name: config-volume
        mountPath: /etc/kubernetes/my-scheduler
  hostNetwork: false
  hostPID: false
  volumes:
    - name: config-volume
      configMap:
        name: my-scheduler-config

• 새로운 scheduler로 생성할 pod

apiVersion: v1 
kind: Pod 
metadata:
  name: nginx 
spec:
  schedulerName: my-scheduler
  containers:
  - image: nginx
    name: nginx

• 이벤트 확인

$ controlplane ~ ➜  k get events -o wide | grep -i nginx
81s         Normal    Scheduled                 pod/nginx                                    my-scheduler, my-scheduler-my-scheduler   Successfully assigned default/nginx to controlplane                                 81s          1       nginx.1742b180abdcc231
80s         Normal    Pulling                   pod/nginx           spec.containers{nginx}   kubelet, controlplane                     Pulling image "nginx"                                                               80s          1       nginx.1742b180e1fe697c
75s         Normal    Pulled                    pod/nginx           spec.containers{nginx}   kubelet, controlplane                     Successfully pulled image "nginx" in 4.58608765s (4.586095789s including waiting)   75s          1       nginx.1742b181f3590cdb
75s         Normal    Created                   pod/nginx           spec.containers{nginx}   kubelet, controlplane                     Created container nginx                                                             75s          1       nginx.1742b181f680a579
75s         Normal    Started                   pod/nginx           spec.containers{nginx}   kubelet, controlplane                     Started container nginx                                                             75s          1       nginx.1742b182087216a7