Posted on Oct 14, 2021 • Edited on Jul 2, 2022 • Originally published at networkandcode.github.io

Bootstrap a Kubernetes cluster with RKE

Rancher Kubernetes Engine ( RKE ) is a popular tool using which we can bootstrap kubernetes clusters
quickly. We are going to excatly see that in this post. Please ensure kubectl is installed in your
system so that you can interact with the cluster after its launched. And You should be aware of the
ssh key generation process.

We are going to perform this setup on a 3 node cluster comprising of 1 master and 2 worker nodes.
The master node is our control plane node, that would also have etcd in it.

I have launched 3 * 4 GB Ubuntu 21.04 nodes on Linode cloud for this purpose. You can launch the VMs
anywhere though. Here are the screenshots of the settings I have chosen while launching a node.

Once the nodes have started up, please make a note of their IPs (private and public)

Alright, lets generate cluster.yml, which would be the config for rke. The complete config would look
like the following.

$ cat cluster.yml # If you intened to deploy Kubernetes in an air-gapped environment, # please consult the documentation on how to configure custom RKE images. nodes: - address: <public ip of master> port: "22" internal_address: <private ip of master> role: - controlplane - etcd hostname_override: master user: root docker_socket: /var/run/docker.sock ssh_key: "" ssh_key_path: ~/.ssh/id_rsa ssh_cert: "" ssh_cert_path: "" labels: {} taints: [] - address: <public ip of node1> port: "22" internal_address: <private ip of node1> role: - worker hostname_override: node1 user: root docker_socket: /var/run/docker.sock ssh_key: "" ssh_key_path: ~/.ssh/id_rsa ssh_cert: "" ssh_cert_path: "" labels: {} taints: [] - address: <public ip of node2> port: "22" internal_address: <private ip of node2> role: - worker hostname_override: node2 user: root docker_socket: /var/run/docker.sock ssh_key: "" ssh_key_path: ~/.ssh/id_rsa ssh_cert: "" ssh_cert_path: "" labels: {} taints: [] services: etcd: image: "" extra_args: {} extra_binds: [] extra_env: [] win_extra_args: {} win_extra_binds: [] win_extra_env: [] external_urls: [] ca_cert: "" cert: "" key: "" path: "" uid: 0 gid: 0 snapshot: null retention: "" creation: "" backup_config: null kube-api: image: "" extra_args: {} extra_binds: [] extra_env: [] win_extra_args: {} win_extra_binds: [] win_extra_env: [] service_cluster_ip_range: 10.43.0.0/16 service_node_port_range: "" pod_security_policy: false always_pull_images: false secrets_encryption_config: null audit_log: null admission_configuration: null event_rate_limit: null kube-controller: image: "" extra_args: {} extra_binds: [] extra_env: [] win_extra_args: {} win_extra_binds: [] win_extra_env: [] cluster_cidr: 10.42.0.0/16 service_cluster_ip_range: 10.43.0.0/16 scheduler: image: "" extra_args: {} extra_binds: [] extra_env: [] win_extra_args: {} win_extra_binds: [] win_extra_env: [] kubelet: image: "" extra_args: {} extra_binds: [] extra_env: [] win_extra_args: {} win_extra_binds: [] win_extra_env: [] cluster_domain: cluster.local infra_container_image: "" cluster_dns_server: 10.43.0.10 fail_swap_on: false generate_serving_certificate: false kubeproxy: image: "" extra_args: {} extra_binds: [] extra_env: [] win_extra_args: {} win_extra_binds: [] win_extra_env: [] network: plugin: canal options: {} mtu: 0 node_selector: {} update_strategy: null tolerations: [] authentication: strategy: x509 sans: [] webhook: null addons: "" addons_include: [] system_images: etcd: rancher/coreos-etcd:v3.4.15-rancher1 alpine: rancher/rke-tools:v0.1.75 nginx_proxy: rancher/rke-tools:v0.1.75 cert_downloader: rancher/rke-tools:v0.1.75 kubernetes_services_sidecar: rancher/rke-tools:v0.1.75 kubedns: rancher/k8s-dns-kube-dns:1.15.2 dnsmasq: rancher/k8s-dns-dnsmasq-nanny:1.15.2 kubedns_sidecar: rancher/k8s-dns-sidecar:1.15.2 kubedns_autoscaler: rancher/cluster-proportional-autoscaler:1.7.1 coredns: rancher/coredns-coredns:1.6.9 coredns_autoscaler: rancher/cluster-proportional-autoscaler:1.7.1 nodelocal: rancher/k8s-dns-node-cache:1.15.7 kubernetes: rancher/hyperkube:v1.18.20-rancher1 flannel: rancher/coreos-flannel:v0.12.0 flannel_cni: rancher/flannel-cni:v0.3.0-rancher6 calico_node: rancher/calico-node:v3.13.4 calico_cni: rancher/calico-cni:v3.13.4 calico_controllers: rancher/calico-kube-controllers:v3.13.4 calico_ctl: rancher/calico-ctl:v3.13.4 calico_flexvol: rancher/calico-pod2daemon-flexvol:v3.13.4 canal_node: rancher/calico-node:v3.13.4 canal_cni: rancher/calico-cni:v3.13.4 canal_flannel: rancher/coreos-flannel:v0.12.0 canal_flexvol: rancher/calico-pod2daemon-flexvol:v3.13.4 weave_node: weaveworks/weave-kube:2.6.4 weave_cni: weaveworks/weave-npc:2.6.4 pod_infra_container: rancher/pause:3.1 ingress: rancher/nginx-ingress-controller:nginx-0.35.0-rancher2 ingress_backend: rancher/nginx-ingress-controller-defaultbackend:1.5-rancher1 metrics_server: rancher/metrics-server:v0.3.6 windows_pod_infra_container: rancher/kubelet-pause:v0.1.6 ssh_key_path: ~/.ssh/id_rsa ssh_cert_path: "" ssh_agent_auth: false authorization: mode: rbac options: {} ignore_docker_version: null kubernetes_version: "" private_registries: [] ingress: provider: "" options: {} node_selector: {} extra_args: {} dns_policy: "" extra_envs: [] extra_volumes: [] extra_volume_mounts: [] update_strategy: null http_port: 0 https_port: 0 network_mode: "" tolerations: [] cluster_name: "" cloud_provider: name: "" prefix_path: "" win_prefix_path: "" addon_job_timeout: 0 bastion_host: address: "" port: "" user: "" ssh_key: "" ssh_key_path: "" ssh_cert: "" ssh_cert_path: "" monitoring: provider: "" options: {} node_selector: {} update_strategy: null replicas: null tolerations: [] restore: restore: false snapshot_name: "" dns: null

Just replace the public and private IPs of nodes in this file and you are good to go. If you want more
customization, you can also generate this config using the rke step by step prompt by saying

rke config --name cluster.yml

.

Please ensure docker is installed on all three nodes. You just need to ssh in to each node, and run

apt update -y && apt install docker.io -y

. Use sudo if required.

Fine, let's now go ahead and lauch the cluster.

networkandcode@ubuntu20:~$ rke up INFO[0000] Running RKE version: v1.1.19 INFO[0000] Initiating Kubernetes cluster INFO[0000] [certificates] GenerateServingCertificate is disabled, checking if there are unused kubelet certificates INFO[0000] [certificates] Generating admin certificates and kubeconfig INFO[0000] Successfully Deployed state file at [./cluster.rkestate] INFO[0000] Building Kubernetes cluster ---TRUNCATED--- NFO[0190] [addons] Executing deploy job rke-ingress-controller INFO[0191] [ingress] ingress controller nginx deployed successfully INFO[0191] [addons] Setting up user addons INFO[0191] [addons] no user addons defined INFO[0191] Finished building Kubernetes cluster successfully

The cluster is ready, you can copy the kubeconfig as follows.

$ mkdir .kube $ touch .kube/config $ cp kube_config_cluster.yml .kube/config

Thats it, you should see the nodes with kubectl.

networkandcode@ubuntu20:~$ kubectl config current-context local networkandcode@ubuntu20:~$ kubectl get nodes NAME STATUS ROLES AGE VERSION master Ready controlplane,etcd 16h v1.18.20 node1 Ready worker 6m20s v1.18.20 node2 Ready worker 7m27s v1.18.20

So as we saw, creating a cluster with RKE is quick, and we can apply this concept to VMs on cloud or
on premises.

Thats the end of the post, Thank you for reading...

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