Changing the IP in my Kubernetes cluster from 10.32.0.0/12 to 172.31.0.0/18

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1

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Cluster information:

Kubernetes version:
Cloud being used: (put bare-metal if not on a public cloud) bare metal
Installation method: kubeadm
Host OS: Ubuntu 18.04.3 LTS
CNI and version: weave
CRI and version:
Hi,
I am trying to change the cidr for my kubernetes cluster which is using a weave cni plugin using cidr /18
curl -fsSLo weave-172subnet-daemonset.yaml "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d ‘\n’)&env.IPALLOC_RANGE=172.31.0.0/18"

Weave is installed and pods are up and running

The problem i am facing is when i deploy a jenkins as container it still doesnot point to new cidr

Name: jenkins-deployment-6c7d7949f4-97vmx
Namespace: default
Priority: 0
Node: k8s-jenkins-slave/10.41.80.43
Start Time: Wed, 17 Jun 2020 08:43:11 +0000
Labels: app=jenkins
pod-template-hash=6c7d7949f4

Status: Running
IP: 10.244.1.2
IPs:
IP:  **10.244.1.2**
Controlled By: ReplicaSet/jenkins-deployment-6c7d7949f4
Containers:
jenkins:
Container ID: docker://30438bbb9af92c319d084ad7216d39db5329332d70ecbfc66cbfc1a80d150e20
Image: jenkins/jenkins:2.222.3
Image ID: docker-pullable://jenkins/jenkins@sha256:15fca69266f4cc2107449d9fa2595acf0cbe1584eb425ee6f2fe9cefc9fc4b97
Ports: 8080/TCP, 50000/TCP
Host Ports: 0/TCP, 0/TCP
State: Running

when i describe the core dns  output is like this:

Name:                 coredns-66bff467f8-vfkcc
Namespace:            kube-system
Priority:             2000000000
Priority Class Name:  system-cluster-critical
Node:                 k8s-jenkins-master/10.41.80.44
Start Time:           Wed, 17 Jun 2020 07:50:54 +0000
Labels:               k8s-app=kube-dns
                      pod-template-hash=66bff467f8
Annotations:          <none>
Status:               Running
IP:                   **10.244.0.3**
IPs:
  IP:           **10.244.0.3**
Controlled By:  ReplicaSet/coredns-66bff467f8
Containers:
  coredns:
    Container ID:  /6baba323dcf59c6840fedcb08f3f6b553e01c96f3b5d91c7fd1a03345e5f0b73
    Image:         k8s.gcr.io/coredns:1.6.7
    Image ID:      docker-k8s.gcr.io/coredns@sha256:2c8d61c46f484d881db43b34d13ca47a269336e576c81cf007ca740fa9ec0800
    Ports:         53/UDP, 53/TCP, 9153/TCP
    Host Ports:    0/UDP, 0/TCP, 0/TCP
    Args:
      -conf
      /etc/coredns/Corefile
    State:          Running
      Started:      Wed, 17 Jun 2020 07:51:15 +0000
    Ready:          True
    Restart Count:  0
    Limits:
      memory:  170Mi
    Requests:
      cpu:        100m
      memory:     70Mi
    Environment:  <none>
    Mounts:
      /etc/coredns from config-volume (ro)
      /var/run/secrets/kubernetes.io/serviceaccount from coredns-token-dj6pn (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  config-volume:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      coredns
    Optional:  false
  coredns-token-dj6pn:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  coredns-token-dj6pn
    Optional:    false
QoS Class:       Burstable
Node-Selectors:  kubernetes.io/os=linux
Events:          <none>


However describing the weave pod contains the new cidr while setting it up
Can you please guide me where i am getting it wrong?
2

You would like to see the coredns ip addr change after installing weave?
That’s not possible coredns is different. Its manages cluster services and weave manages docker level networking. if i am wrong correct me.

3

the problem i am facing is when i deploy a jenkins as container it still doesnot point to new cidr

Name:         jenkins-deployment-6c7d7949f4-97vmx
Namespace:    default
Priority:     0
Node:         k8s-jenkins-slave/10.41.80.43
Start Time:   Wed, 17 Jun 2020 08:43:11 +0000
Labels:       app=jenkins
              pod-template-hash=6c7d7949f4
              
Status:       Running
IP:           10.244.1.2
IPs:
  IP:           **10.244.1.2**
Controlled By:  ReplicaSet/jenkins-deployment-6c7d7949f4
Containers:
  jenkins:
    Container ID:   docker://30438bbb9af92c319d084ad7216d39db5329332d70ecbfc66cbfc1a80d150e20
    Image:          jenkins/jenkins:2.222.3
    Image ID:       docker-pullable://jenkins/jenkins@sha256:15fca69266f4cc2107449d9fa2595acf0cbe1584eb425ee6f2fe9cefc9fc4b97
    Ports:          8080/TCP, 50000/TCP
    Host Ports:     0/TCP, 0/TCP
    State:          Running
      Started:      Wed, 17 Jun 2020 08:43:38 +0000
    Ready:          True
    Restart Count:  0
    Environment:
      JAVA_OPTS:            -Djenkins.install.runSetupWizard=false
      CASC_JENKINS_CONFIG:  /config-jcasc/jcasc.yml
    Mounts:
      /config-jcasc from jenkins-configmap-vol (rw)
      /var/jenkins_home from jenkins-home (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-srt2v (ro)
  prometheus-sidecar:
    Container ID:  docker://f3d5682dabdfa4bf6e1f13ac54b225d0ed5f642523c9842e9a5721df67032355
    Image:         quay.io/prometheus/node-exporter
    Image ID:      docker-pullable://quay.io/prometheus/node-exporter@sha256:cf66a6bbd573fd819ea09c72e21b528e9252d58d01ae13564a29749de1e48e0f
    Port:          9100/TCP
    Host Port:     0/TCP
    Args:
      --no-collector.arp
      --no-collector.bcache
      --no-collector.bonding
      --no-collector.buddyinfo
      --no-collector.conntrack
      --no-collector.cpu
      --no-collector.cpufreq
      --no-collector.diskstats
      --no-collector.drbd
      --no-collector.edac
      --no-collector.entropy
      --no-collector.filefd
      --no-collector.hwmon
      --no-collector.infiniband
      --no-collector.interrupts
      --no-collector.ipvs
      --no-collector.ksmd
      --no-collector.loadavg
      --no-collector.logind
      --no-collector.mdadm
      --no-collector.meminfo
      --no-collector.meminfo_numa
      --no-collector.mountstats
      --no-collector.netclass
      --no-collector.netdev
      --no-collector.netstat
      --no-collector.nfs
      --no-collector.nfsd
      --no-collector.ntp
      --no-collector.perf
      --no-collector.pressure
      --no-collector.processes
      --no-collector.qdisc
      --no-collector.runit
      --no-collector.sockstat
      --no-collector.stat
      --no-collector.supervisord
      --no-collector.systemd
      --no-collector.tcpstat
      --no-collector.textfile
      --no-collector.time
      --no-collector.timex
      --no-collector.uname
      --no-collector.vmstat
      --no-collector.wifi
      --no-collector.xfs
      --no-collector.zfs
    State:          Running
      Started:      Wed, 17 Jun 2020 08:43:47 +0000
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /data/test from jenkins-home (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-srt2v (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  jenkins-home:
    Type:          HostPath (bare host directory volume)
    Path:          /home/arbs/jenkins-home
    HostPathType:  Directory
  jenkins-configmap-vol:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      jcasc-config
    Optional:  false
  default-token-srt2v:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-srt2v
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>

Events:          <none>