Is there a way to prevent kubectl from de-registering kubernetes nodes

Question

I was testing some commands and I ran

$ kubectl delete nodes --all

and it deletes de-registers all the nodes including the masters. Now I can't connect to the cluster (Well, Obviously as the master is deleted).

Is there a way to prevent this as anyone could accidentally do this?

Extra Info: I am using KOps for deployment.

P.S. It does not delete the EC2 instances and the nodes come up on doing a EC2 instance reboot on all the instances.

Answer 1

By default, you using something like a superuser who can do anything he want with a cluster.

For limit access to a cluster for other users you can use RBAC authorization for. By RBAC rules you can manage access and limits per resource and action.

In few words, for do that you need to:

1. Create new cluster by Kops with --authorization RBAC or modify existing one by adding 'rbac' option to cluster's configuration to 'authorization' section:

2. authorization:
    rbac: {}

3. Now, we can follow that instruction from Bitnami for create a user. For example, let's creating a user which has access only to office namespace and only for a few actions. So, we need to create a namespace firs:

4. kubectl create namespace office

5. Create a key and certificates for new user:

6. openssl genrsa -out employee.key 2048

7. openssl req -new -key employee.key -out employee.csr -subj "/CN=employee/O=bitnami"

8. Now, using your CA authority key (It available in the S3 bucket under PKI) we need to approve new certificate:

9. openssl x509 -req -in employee.csr -CA CA_LOCATION/ca.crt -CAkey CA_LOCATION/ca.key -CAcreateserial -out employee.crt -days 500

10. Creating credentials:

11. kubectl config set-credentials employee --client-certificate=/home/employee/.certs/employee.crt  --client-key=/home/employee/.certs/employee.key

12. Setting a right context:

13. kubectl config set-context employee-context --cluster=YOUR_CLUSTER_NAME --namespace=office --user=employee