CKS - option to define Calico ippool during deployment

[chunkyen]

Hi, I am trying out CKS using the pre-built calico iso on 4.21. It deploys fine but I soon found out that LB backed svc external IP are stucked at pending state. On further troubleshooting, LB was not created on the guest network where the CKS sits on, and it is due to cloud-controller-manager not able to talk to Cloudstack API endpoint.

This is due to an IP CIDR range overlap between the calico default pod CIDR (192.168.0.0/16) and my public network. I can change this easily by editing the ippool crd to a different range and then restarting all the pods using the old range. Once they are restarted, they will get the new range and external comm will work correctly.

However, I was wondering is there a way for me to specify the pod cidr during CKS creation. I felt it is possible using the CNI configuration however I have trouble trying to configure the CNI config correctly as docuemntation and examples are extremely limited in this area.
Can someone give me some pointers on how I can write the CNI config? Thanks

[kiranchavala]

@chunkyen
By default, Calico uses the 192.168.0.0/16 network for its pod IP pool when you install it with the standard manifests.

During the CKS ISO creation we have used the default calico yaml

./create-kubernetes-binaries-iso.sh ./ 1.33.1 1.7.1 1.33.0 https://raw.githubusercontent.com/projectcalico/calico/v3.30.0/manifests/calico.yaml https://raw.githubusercontent.com/kubernetes/dashboard/v2.7.0/aio/deploy/recommended.yaml setup-v1.33.1-calico

Once the cks is deployed check the ippool that is being used for pods

kubectl get ippool.crd.projectcalico.org -o yaml

You can edit the IP pool to change the CIDR to a different subnet that fits your network architecture better. For example, you might choose to use 10.0.0.0/16.

kubectl edit ippool default-ipv4-ippool

Redeploy the pods

kubectl delete pod –all -A

[chunkyen]

Thank you for your reply. I was aware of the steps to change Calico to the non overlapping IP range as stated in my original post. I am looking for a way to cusomize these values during the CKS deployment, perhaps using the CNI configuration? I just don't have a very good idea on how this work and the documentation is not very useful in this area.

[kiranchavala]

Thanks @chunkyen , currently its not possible to specify the cluster cidr during the CKS Deployment. It's always 192.168.0.0/16

We will consider this an enhancement request @Pearl1594 @nvazquez

Meanwhile, I will cross-check internally if we can use the custom CNI Configuration to achieve the result