Deploy a Highly Available Kubernetes 1.12.5 Cluster with Kubespray

Overview

The article demonstrates how to build a highly‑available Kubernetes cluster (v1.12.5) using Kubespray (tag v2.8.3), which is driven by Ansible.

Prerequisites

Kubespray source code: https://github.com/kubernetes-sigs/kubespray. Use the released tag v2.8.3 rather than the master branch.

Step 1 Set up password‑less SSH

ssh-keygen -t rsa
scp ~/.ssh/id_rsa.pub root@IP:/root/.ssh
ssh root@IP
cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys

Step 2 Download Kubespray

wget https://github.com/kubernetes-sigs/kubespray/archive/v2.8.3.tar.gz
tar -xvf v2.8.3.tar.gz
cd kubespray-v2.8.3

Step 3 Configuration adjustments

3.1 Private image registry

Define custom image repositories in inventory/testcluster/group_vars/k8s-cluster/k8s-cluster.yml:

# kubernetes image repo define
kube_image_repo: "10.0.0.183:5000/google_containers"
etcd_image_repo: "10.0.0.183:5000/coreos/etcd"
coredns_image_repo: "10.0.0.183:5000/coredns"
calicoctl_image_repo: "10.0.0.183:5000/calico/ctl"
calico_node_image_repo: "10.0.0.183:5000/calico/node"
calico_cni_image_repo: "10.0.0.183:5000/calico/cni"
calico_policy_image_repo: "10.0.0.183:5000/calico/kube-controllers"
hyperkube_image_repo: "{{ kube_image_repo }}/hyperkube-{{ image_arch }}"
pod_infra_image_repo: "{{ kube_image_repo }}/pause-{{ image_arch }}"
dashboard_image_repo: "{{ kube_image_repo }}/kubernetes-dashboard-{{ image_arch }}"

Add the insecure registry entry (the private registry does not use HTTPS) in inventory/testcluster/group_vars/all/docker.yml:

docker_insecure_registries:
  - 10.0.0.183:5000

3.2 Docker CE source mirror

Replace the default Docker CE repository with Alibaba Cloud mirrors by adding the following variables to inventory/testcluster/group_vars/k8s-cluster/k8s-cluster.yml:

# CentOS/RedHat docker‑ce repo
docker_rh_repo_base_url: 'https://mirrors.aliyun.com/docker-ce/linux/centos/7/$basearch/stable'
docker_rh_repo_gpgkey: 'https://mirrors.aliyun.com/docker-ce/linux/centos/gpg'
dockerproject_rh_repo_base_url: 'https://mirrors.aliyun.com/docker-engine/yum/repo/main/centos/7'
dockerproject_rh_repo_gpgkey: 'https://mirrors.aliyun.com/docker-engine/yum/gpg'

3.3 Pre‑download required binaries

Binary URLs are defined in roles/download/defaults/main.yml. Example URLs for Kubernetes v1.12.5:

kubeadm_download_url: "https://storage.googleapis.com/kubernetes-release/release/v1.12.5/bin/linux/amd64/kubeadm"
hyperkube_download_url: "https://storage.googleapis.com/kubernetes-release/release/v1.12.5/bin/linux/amd64/hyperkube"
cni_download_url: "https://github.com/containernetworking/plugins/releases/download/v0.6.0/cni-plugins-amd64-v0.6.0.tgz"

After downloading, make the files executable and copy them to each node (e.g., node1):

chmod 755 cni-plugins-amd64-v0.6.0.tgz hyperkube kubeadm
scp cni-plugins-amd64-v0.6.0.tgz hyperkube kubeadm root@node1:/tmp/releases

3.4 DNS and network plugin selection

Use coredns as the DNS provider. Set resolvconf_mode: docker_dns so that containers using host networking can resolve cluster DNS: resolvconf_mode: docker_dns Select Calico as the CNI plugin and enable IPVS mode for kube-proxy. The following diagram shows the network topology (image retained for technical reference):

Step 4 Run the Ansible playbook

sudo pip install -r requirements.txt
cp -rfp inventory/sample inventory/mycluster
declare -a IPS=(10.10.1.3 10.10.1.4 10.10.1.5)
CONFIG_FILE=inventory/mycluster/hosts.ini python3 contrib/inventory_builder/inventory.py ${IPS[@]}
# optional: review variables
cat inventory/mycluster/group_vars/all/all.yml
cat inventory/mycluster/group_vars/k8s-cluster/k8s-cluster.yml
ansible-playbook -i inventory/mycluster/hosts.ini --become --become-user=root cluster.yml

After the playbook completes, verify the cluster from a master node:

kubectl cluster-info
kubectl get node
kubectl get pods --all-namespaces

References

Kubespray getting‑started guide: https://github.com/kubernetes-sigs/kubespray/blob/master/docs/getting-started.md

Community write‑ups: https://xdatk.github.io/2018/04/16/kubespray2/ and https://jicki.me/kubernetes/docker/2018/12/21/k8s-1.13.1-kubespray/