This guide covers the step-by-step process of installing Kubernetes using the `kubeadm` utility. `kubeadm` is a tool recommended for bootstrapping a Kubernetes cluster. We will use 3 nodes: a master node and 2 worker nodes. The nodes will run on AWS EC2 instances with Ubuntu 20.04 LTS (t2.medium instance type, 8GB storage). You can use any cloud provider to launch the instances. ## Prerequisites #### Infrastructure Requirements: - Instance Type: t2.medium or better. - Storage: 8GB minimum. - Operating System: Ubuntu 20.04 LTS. - Network: Ensure all nodes are in the same VPC with required ports opened. #### Tools: - SSH client (e.g., ssh or PuTTY). - curl, vi or nano (pre-installed in Ubuntu). #### Required Ports: (Ensure these are allowed in the security group) These ports are required for the Kubernetes cluster to work. Check the [Kubernetes documentation](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#check-required-ports) for more information. ##### Master Node: - TCP: 6443 (Kubernetes API Server) - TCP: 2379-2380 (Etcd) - TCP: 10250 (Kube Scheduler) - TCP: 10257 (Kube Controller Manager) - TCP: 10250 (Kubelet API) - TCP: 22 (SSH) - ICMP: (Ping Connection) ![Master node inbound rules](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/dzmyw2wonurfcq5rvsrq.png) ##### Worker Nodes: - TCP: 10256 (Kube Proxy) - TCP: 30000-32767 (NodePort Services) - TCP: 10250 (Kubelet API) - TCP: 22 (SSH) - ICMP: (Ping Connection) ![Worker node inbound rules](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/rc0wq6hl73v2fk7covfe.png) ## Step-by-Step Setup ### 1. Launch EC2 Instances - Configuration: - Instance Type: t2.medium - AMI: Ubuntu 20.04 LTS - Storage: 8GB - Key Pair: Create or use an existing one. - Assign Public IP: Yes. - Result: Master and Worker Nodes ![Master and Worker Nodes](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/o7f130hq3w9sqe7rgwlv.png) ### 2. Connect to Instances and Set Hostnames Setting a hostname ensures each node has a unique identifier, simplifying management and troubleshooting. #### Master Node ```bash ssh -i "key-pair-name.pem" ubuntu@master-node-ip hostnamectl set-hostname master ``` ![Master Node](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/j4whnayr2lk2test2wsp.png) ### Worker Nodes (worker-1, worker-2) ```bash ssh -i "key-pair-name.pem" ubuntu@worker-node-ip hostnamectl set-hostname worker-[1-2] ``` ![Worker Node 1](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/3gspeabm2rs32ne5ppn8.png) ![Worker Node 2](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/2dfwesuelsz8pdkym1ts.png) ### 3. Test Node Connectivity Verifies that the nodes can communicate with each other, which is essential for Kubernetes components to function correctly. #### From Master Node ```bash ping worker-1-ip ping worker-2-ip ``` ![test-connectivity](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qre42eietenkivkl7wzy.png) ### 4. Disable Swap memory on all nodes Kubernetes requires swap to be disabled to ensure proper memory allocation for containers. #### Temporary (until reboot) ```bash sudo swapoff -a ``` #### Permanent ```bash sudo sed -i.bak '/ swap / s/^/#/' /etc/fstab ``` ![disable-swap-master](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/9mgt3myn4ero37u06xfi.png) ![disable-swap-worker-1](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/bo53taveb3crgxla7zo1.png) ![disable-swap-worker-2](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/56qe54kr7i3ykpv01qs0.png) ### 5. Enable Overlay and Bridge Filtering Modules These kernel modules enable container network communication and ensure traffic routing works properly within the cluster. These settings allow the Kubernetes networking model to function correctly by enabling packet forwarding and bridge filtering. ```bash cat < /var/lib/kubelet/config.yaml # kubeadm-config.yaml kind: ClusterConfiguration apiVersion: kubeadm.k8s.io/v1beta4 kubernetesVersion: v1.21.0 --- kind: KubeletConfiguration apiVersion: kubelet.config.k8s.io/v1beta1 cgroupDriver: systemd EOF" ``` ![kubelet configuration - master](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/cq0epz6g0q42ozcq4vhr.png) ![kubelet configuration - worker-1](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/br0rxai3hk0o9vt2onrp.png) ![kubelet configuration - worker-2](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/6j6ssqm6qncns2wp2axu.png) ### 8. Setup Kubernetes Cluster Bootstraps the master node, specifying the network CIDR and the API server's address. #### Master Node ```bash sudo kubeadm init --pod-network-cidr=192.168.0.0/16 --apiserver-advertise-address= --node-name master ``` ![kubeadm init](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/cod1kcgmk9nlbni4c3gj.png) #### Setup Kubectl for Regular User and List the Nodes Configures kubectl to interact with the cluster. ```bash mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config kubectl get nodes ``` ![nodes](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/r2736or7lg3rjily9ywo.png) #### Install Calico CNI on Master Node Deploys Calico as the network plugin for Kubernetes, enabling pod communication across the cluster. ```bash kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.28.0/manifests/tigera-operator.yaml curl -O https://raw.githubusercontent.com/projectcalico/calico/v3.28.0/manifests/custom-resources.yaml kubectl apply -f custom-resources.yaml ``` ![Calico-cni](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/b56vcwx35ary65oud9bw.png) #### Get All Pods ```bash kubectl get pods -A ``` ![All pods on master node](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/xgc4nfgjapqx58t98tjd.png) #### Generate a token for worker nodes and run the output command on worker nodes ```bash kubeadm token create --print-join-command ``` Output should be similar to this: ```bash kubeadm join 10.0.0.10:6443 --token --discovery-token-ca-cert-hash sha256: ``` ![kubeadm join - worker-1](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/feqt4g50tsrikws1wps4.png) ![kubeadm join - worker-2](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/3ws4uqwjtgpyd86j6qjc.png) #### List all the nodes in the cluster After successfully joining the worker nodes to the cluster, list the nodes in the cluster. ```bash kubectl get nodes ``` ![List all the nodes in the cluster](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/2ksgyo943dh4v4al56nr.png) ### 9. Deploy an Nginx Pod and Expose it as a NodePort Service Deploys a sample application (Nginx) and makes it accessible outside the cluster for testing. ```bash kubectl run nginx --image=nginx --port=80 kubectl expose pod nginx --port=80 --target-port=80 --type=NodePort ``` ![Deploy an Nginx pod and expose it as a NodePort service](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qp4fb31g2cwtk2eudqoy.png) #### Nginx Page in the Browser ![Nginx page in the browser](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/nh5tn1vhqxvnlc2vwgx0.png) ## Notes - Troubleshooting: - Use kubectl describe node for node issues. - Use kubectl logs for pod issues. - Verify CNI installation using kubectl get pods -n kube-system. - Next Steps: - Monitor the cluster using tools like Prometheus. - Scale up the cluster with additional worker nodes. ## Conclusion Congratulations! 🎉 You've successfully deployed a Kubernetes cluster using `kubeadm` and set up a sample Nginx application to validate your setup. This guide has walked you through every step, from preparing your nodes to launching your first pod. With your Kubernetes cluster up and running, you're now ready to explore the endless possibilities it offers, from deploying scalable applications to experimenting with advanced concepts like autoscaling, monitoring, and service meshes.

dirudeen

Installing Kubernetes using Kubeadm utility

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