working with daemonset with node

Daemonsets: A DaemonSet ensures that all Nodes run a copy of a Pod. As nodes are added to the cluster, Pods are added to them. Examples of a daemon set would be running your logging or monitoring agent on your nodes.

daemonset.yaml

apiVersion: apps/v1beta2
kind: DaemonSet
metadata:
  name: example-daemonset
  namespace: default
  labels:
    k8s-app: example-daemonset
spec:
  selector:
    matchLabels:
      name: example-daemonset
  template:
    metadata:
      labels:
        name: example-daemonset
    spec:
      #nodeSelector: minikube # Specify if you want to run on specific nodes
      containers:
      - name: example-daemonset
        image: busybox
        args:
        - /bin/sh
        - -c
        - date; sleep 1000
        resources:
          limits:
            memory: 200Mi
          requests:
            cpu: 100m
            memory: 200Mi
      terminationGracePeriodSeconds: 30

daemonset-infra-prod.yaml

apiVersion: apps/v1beta2
kind: DaemonSet
metadata:
  name: prod-daemonset
  namespace: default
  labels:
    k8s-app: prod-daemonset
spec:
  selector:
    matchLabels:
      name: prod-daemonset
  template:
    metadata:
      labels:
        name: prod-daemonset
    spec:
      containers:
      - name: prod-daemonset
        image: busybox
        args:
        - /bin/sh
        - -c
        - date; echo "hello prod"; sleep 1000
        resources:
          limits:
            memory: 200Mi
          requests:
            cpu: 100m
            memory: 200Mi
      terminationGracePeriodSeconds: 30
      nodeSelector: 
        infra: "production"

daemonset-infra-dev.yaml

apiVersion: apps/v1beta2
kind: DaemonSet
metadata:
  name: dev-daemonset
  namespace: default
  labels:
    k8s-app: dev-daemonset
spec:
  selector:
    matchLabels:
      name: dev-daemonset
  template:
    metadata:
      labels:
        name: dev-daemonset
    spec:
      containers:
      - name: dev-daemonset
        image: busybox
        args:
        - /bin/sh
        - -c
        - date; echo "hello dev"; ping xunyangit.wordpress.com -c 4; sleep 10
        resources:
          limits:
            memory: 200Mi
          requests:
            cpu: 100m
            memory: 200Mi
      terminationGracePeriodSeconds: 30
      nodeSelector: 
        infra: "development"

create 3 different daemonset

kubectl create -f daemonset.yaml 
kubectl create -f daemonset-infra-prod.yaml 
kubectl create -f daemonset-infra-development.yaml 

localhost:~ xunyang$ kubectl get nodes --show-labels
NAME       STATUS    ROLES     AGE       VERSION   LABELS
minikube   Ready     master    1d        v1.10.0   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/hostname=minikube,node-role.kubernetes.io/master=
localhost:~ xunyang$ kubectl get daemonset
NAME                DESIRED   CURRENT   READY     UP-TO-DATE   AVAILABLE   NODE SELECTOR       AGE
dev-daemonset       0         0         0         0            0           infra=development   16m
example-daemonset   1         1         1         1            1           <none>              52m
prod-daemonset      0         0         0         0            0           infra=production    52m
kubectl label node minikube infra=production
localhost:~ xunyang$ kubectl get daemonset
NAME                DESIRED   CURRENT   READY     UP-TO-DATE   AVAILABLE   NODE SELECTOR       AGE
dev-daemonset       0         0         0         0            0           infra=development   17m
example-daemonset   1         1         1         1            1           <none>              53m
prod-daemonset      1         1         1         1            1           infra=production    53m
localhost:~ xunyang$ kubectl get daemonset
NAME                DESIRED   CURRENT   READY     UP-TO-DATE   AVAILABLE   NODE SELECTOR       AGE
dev-daemonset       1         1         0         1            0           infra=development   18m
example-daemonset   1         1         1         1            1           <none>              54m
prod-daemonset      0         0         0         0            0           infra=production    54m
localhost:~ xunyang$ kubectl get daemonset
NAME                DESIRED   CURRENT   READY     UP-TO-DATE   AVAILABLE   NODE SELECTOR       AGE
dev-daemonset       1         1         1         1            1           infra=development   18m
example-daemonset   1         1         1         1            1           <none>              54m
prod-daemonset      0         0         0         0            0           infra=production    54m

check pod logs

localhost:~ xunyang$ kubectl get pod
NAME                      READY     STATUS    RESTARTS   AGE
dev-daemonset-ktdtn       1/1       Running   1          10m
example-daemonset-46t5j   1/1       Running   2          55m
localhost:~ xunyang$ kubectl logs dev-daemonset-ktdtn
Mon Apr 16 10:27:17 UTC 2018
hello dev
PING xunyangit.wordpress.com (192.0.78.13): 56 data bytes
64 bytes from 192.0.78.13: seq=0 ttl=61 time=158.607 ms
64 bytes from 192.0.78.13: seq=1 ttl=61 time=160.128 ms
64 bytes from 192.0.78.13: seq=2 ttl=61 time=162.701 ms
64 bytes from 192.0.78.13: seq=3 ttl=61 time=160.225 ms

--- xunyangit.wordpress.com ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 158.607/160.415/162.701 ms
localhost:~ xunyang$ kubectl logs dev-daemonset-ktdtn
Mon Apr 16 10:27:49 UTC 2018
hello dev
PING xunyangit.wordpress.com (192.0.78.12): 56 data bytes
64 bytes from 192.0.78.12: seq=0 ttl=61 time=155.594 ms
64 bytes from 192.0.78.12: seq=1 ttl=61 time=154.204 ms
64 bytes from 192.0.78.12: seq=2 ttl=61 time=155.583 ms
64 bytes from 192.0.78.12: seq=3 ttl=61 time=156.444 ms

--- xunyangit.wordpress.com ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 154.204/155.456/156.444 ms