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First, there are some minimum requirements to be met and steps to take before proceeding with the installation of Kubeadm (complete guide https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/official guide):
- CentOS 7 (minimum supported version);
- at least 2 GB of RAM and 2 CPUs per machine;
- opening doors on the control plane (6443, 2379-2380, 10250-10252) and on the worker (10250, 30000-32767);
- install Docker on the nodes (https://docs.docker.com/engine/install/centos/official guide);
- complete connectivity between the cluster nodes and uniqueness of MAC address and product_uuid for each node;
- swap disabled on nodes.
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