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I have VPC setup on Google Cloud which has 192.0.0.0/24 as subnet in which I am trying to setup k8s cluster for following servers ,

VM   :  VM NAME     : Internal IP     
VM 1 : k8s-master   : 192.24.1.4
VM 2 : my-machine-1 : 192.24.1.1
VM 3 : my-machine-2 : 192.24.1.3
VM 4 : my-machine-3 : 192.24.1.2

Here k8s-master would act as a master and all other 3 machines would act as nodes. I am using following command to initilize my cluster.

sudo kubeadm init --pod-network-cidr=10.244.0.0/16 ( need to change this to vpc subnet) --apiserver-advertise-address=0.0.0.0 --apiserver-cert-extra-sans=k8s-master-external-ip

I am using flannel for which I am using following command to setup network for my cluster,

sudo kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Now whenever I am deploying a new pod, k8s is assigning IP from 10.244.0.0/16 to that pod which is not accessible from my eureka as my eureka server is running on Google Cloud VPC cidr.

I want to configure k8s such that it will use vpc subnet IP ( internal IP of the machine where pod is deployed ).

I even tried to manually download kube-flannel.yml and change cidr to my subnet but that did not solve my problem.

Need help to resolve this. Thanks in advance.

TheAkashKamble
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1 Answers1

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Kubernetes needs 3 subnets.

1 Subnet for the nodes (this would your vpc subnet 192.168.1.0/24) 1 Subnet for your pods. Optionally 1 Subnet for Services.

These subnets cannot be the same they have to be different.

I believe what's missing in your case are routes to make the pods talk to each other. Have a look at this guide for setting up the routes you need

boredabdel
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  • Will this work for manual setup of k8s? I am doing manual installation of k8s on 1 vm ( k8s master ). In this hybrid approach only handful services would be deployed using k8s all other would be deployed via docker compose file. Here the problem is my eureka server is not able to connect to k8s pod as it runs on different subnet and eureka runs on different subnet. Could you please suggest a way out for this ? – TheAkashKamble Jan 13 '22 at 07:54
  • I'm talking about Kubernetes here not GKE. You need at least 2 subnets for your Kubernetes Cluster regardless of it's size. Also if you deploy apps into Kubernetes you should not use the POD IP's to talk the Service running in the cluster, pod IP's change depending on which node ends up hosting the pod. – boredabdel Jan 13 '22 at 10:21