Kubernetes installation using Kubespray

In this document, we’ll install Kubernetes v1.29 using Kubespray on a 2-node cluster.

There are several ways to use Kubespray to deploy a Kubernetes cluster. In this document, we choose to use the Ansible way. For other ways to use Kubespary, refer to Kubespray’s document.

Node preparation

hostname	ip address	Operating System
k8s-master	192.168.121.35/24	Ubuntu 22.04
k8s-worker	192.168.121.133/24	Ubuntu 22.04

We assume these two machines are used for Kubernetes 2-node cluster. They have direct internet access both in bash terminal and in apt repository.

If on any of the above 2 nodes, you have previously installed either Kubernetes, or any other container runtime(i.e. docker, containerd, etc.), please make sure you have clean-up those first. Refer to Kubernetes installation demo using kubeadm to clean up the environment.

Prerequisites

We assume that there is a third machine as your operating machine. You can log in to this machine and execute the Ansible command. Any of the above two K8s nodes can be used as the operating machine. Unless otherwise specified, all the following operations are performed on the operating machine.

Please make sure that the operating machine can login to both K8s nodes via SSH without a password prompt. There are different ways to configure the ssh login without password promotion. A simple way is to copy the public key of the operating machine to the K8s nodes. For example:

# generate key pair in the operation machine
ssh-keygen -t rsa -b 4096
# manually copy the public key to the K8s master and worker nodes
cat ~/.ssh/id_rsa.pub | ssh username@k8s-master "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"
cat ~/.ssh/id_rsa.pub | ssh username@k8s-worker "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

Step 1. Set up Kubespray and Ansible

Python3 (version >= 3.10) is required in this step. If you don’t have, go to Python website for installation guide.

You shall set up a Python virtual environment and install Ansible and other Kubespray dependencies. Simply, you can just run following commands. You can also go to Kubespray Ansible installation guide for details. To get the kubespray code, please check out the latest release version tag of kubespray. Here we use kubespary v2.25.0 as an example.

git clone https://github.com/kubernetes-sigs/kubespray.git
VENVDIR=kubespray-venv
KUBESPRAYDIR=kubespray
python3 -m venv $VENVDIR
source $VENVDIR/bin/activate
cd $KUBESPRAYDIR
# Check out the latest release version tag of kubespray.
git checkout v2.25.0
pip install -U -r requirements.txt

Step 2. Build your own inventory

Ansible inventory defines the hosts and groups of hosts on which Ansible tasks are to be executed. You can copy a sample inventory with following command:

cp -r inventory/sample inventory/mycluster

Edit your inventory file inventory/mycluster/inventory.ini to config the node name and IP address. The inventory file used in this demo is as follows:

[all]
k8s-master ansible_host=192.168.121.35
k8s-worker ansible_host=192.168.121.133

[kube_control_plane]
k8s-master

[etcd]
k8s-master

[kube_node]
k8s-master
k8s-worker

[calico_rr]

[k8s_cluster:children]
kube_control_plane
kube_node
calico_rr

Step 3. Define Kubernetes configuration

Kubespray gives you ability to customize Kubernetes instalation, for example define:

• network plugin

• container manager

• kube_apiserver_port

• kube_pods_subnet

• all K&s addons configurations, or even define to deploy cluster on hyperscaller like AWS or GCP. All of those settings are stored in group vars defined in inventory/mycluster/group_vars

For K&s settings look in inventory/mycluster/group_vars/k8s_cluster/k8s-cluster.yml

NOTE: If you noted issues on TASK [kubernetes/control-plane : Kubeadm | Initialize first master] in K& deployment, change the port on which API Server will be listening on from 6443 to 8080. By default Kubespray configures kube_control_plane hosts with insecure access to kube-apiserver via port 8080. Refer to kubespray getting-started

# The port the API Server will be listening on.
kube_apiserver_ip: "{{ kube_service_addresses | ansible.utils.ipaddr('net') | ansible.utils.ipaddr(1) | ansible.utils.ipaddr('address') }}"
kube_apiserver_port: 8080  # (http)

Step 4. Deploy Kubernetes

You can clean up old Kubernetes cluster with Ansible playbook with following command:

# Clean up old Kubernetes cluster with Ansible Playbook - run the playbook as root
# The option `--become` is required, as for example cleaning up SSL keys in /etc/,
# uninstalling old packages and interacting with various systemd daemons.
# Without --become the playbook will fail to run!
# And be mindful that it will remove the current Kubernetes cluster (if it's running)!
ansible-playbook -i inventory/mycluster/inventory.ini  --become --become-user=root -e override_system_hostname=false reset.yml

Then you can deploy Kubernetes with Ansible playbook with following command:

# Deploy Kubespray with Ansible Playbook - run the playbook as root
# The option `--become` is required, as for example writing SSL keys in /etc/,
# installing packages and interacting with various systemd daemons.
# Without --become the playbook will fail to run!
ansible-playbook -i inventory/mycluster/inventory.ini  --become --become-user=root -e override_system_hostname=false cluster.yml

The Ansible playbooks will take several minutes to finish. After playbook is done, you can check the output. If failed=0 exists, it means playbook execution is successfully done.

Step 5. Create kubectl configuration

If you want to use Kubernetes command line tool kubectl on k8s-master node, please login to the node k8s-master and run the following commands:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

If you want to access this Kubernetes cluster from other machines, you can install kubectl by sudo apt-get install -y kubectl and copy over the configuration from the k8-master node and set ownership as above.

Then run following command to check the status of your Kubernetes cluster:

$ kubectl get node
NAME          STATUS   ROLES           AGE     VERSION
k8s-master    Ready    control-plane   31m     v1.29.5
k8s-worker   Ready    <none>          7m31s   v1.29.5
$ kubectl get pods -A
NAMESPACE                    NAME                                       READY   STATUS    RESTARTS   AGE
kube-system                  calico-kube-controllers-68485cbf9c-vwqqj   1/1     Running   0          23m
kube-system                  calico-node-fxr6v                          1/1     Running   0          24m
kube-system                  calico-node-v95sp                          1/1     Running   0          23m
kube-system                  coredns-69db55dd76-ctld7                   1/1     Running   0          23m
kube-system                  coredns-69db55dd76-ztwfg                   1/1     Running   0          23m
kube-system                  dns-autoscaler-6d5984c657-xbwtc            1/1     Running   0          23m
kube-system                  kube-apiserver-satg-opea-0                 1/1     Running   0          24m
kube-system                  kube-controller-manager-satg-opea-0        1/1     Running   0          24m
kube-system                  kube-proxy-8zmhk                           1/1     Running   0          23m
kube-system                  kube-proxy-hbq78                           1/1     Running   0          23m
kube-system                  kube-scheduler-satg-opea-0                 1/1     Running   0          24m
kube-system                  nginx-proxy-satg-opea-3                    1/1     Running   0          23m
kube-system                  nodelocaldns-kbcnv                         1/1     Running   0          23m
kube-system                  nodelocaldns-wvktt                         1/1     Running   0          24m

Now congratulations. Your two-node K8s cluster is ready to use.

Quick reference

How to deploy a single node Kubernetes?

Deploying a single-node K8s cluster is very similar to setting up a multi-node (>=2) K8s cluster.

Follow the previous Step 1. Set up Kubespray and Ansible to set up the environment.

And then in Step 2. Build your own inventory, you can create single-node Ansible inventory by copying the single-node inventory sample as following:

cp -r inventory/local inventory/mycluster

Edit your single-node inventory inventory/mycluster/hosts.ini to replace the node name from node1 to your real node name (for example k8s-master) using following command:

sed -i "s/node1/k8s-master/g" inventory/mycluster/hosts.ini

Then your single-node inventory will look like below:

k8s-master ansible_connection=local local_release_dir={{ansible_env.HOME}}/releases

[kube_control_plane]
k8s-master

[etcd]
k8s-master

[kube_node]
k8s-master

[k8s_cluster:children]
kube_node
kube_control_plane

And then follow Step 3. Deploy Kubernetes, please pay attention to the inventory name while executing Ansible playbook, which is inventory/mycluster/hosts.ini in single node deployment. When the playbook is executed successfully, you will get a 1-node K8s ready.

And the follow Step 4. Create kubectl configuration to set up kubectl. You can check the status by kubectl get nodes.

How to scale Kubernetes cluster to add more nodes?

Assume you’ve already have a two-node K8s cluster and you want to scale it to three nodes. The third node information is:

hostname	ip address	Operating System
third-node	192.168.121.134/24	Ubuntu 22.04

Make sure the third node has internet access and can be logged in via SSH without password promotion from your operating machine.

Edit your Ansible inventory file to add the third node information to [all] and [kube_node] section as following:

[all]
k8s-master ansible_host=192.168.121.35
k8s-worker ansible_host=192.168.121.133
third-node ansible_host=192.168.121.134

[kube_control_plane]
k8s-master

[etcd]
k8s-master

[kube_node]
k8s-master
k8s-worker
third-node

[calico_rr]

[k8s_cluster:children]
kube_control_plane
kube_node
calico_rr

Then you can deploy Kubernetes to the third node with Ansible playbook with following command:

# Deploy Kubespray with Ansible Playbook - run the playbook as root
# The option `--become` is required, as for example writing SSL keys in /etc/,
# installing packages and interacting with various systemd daemons.
# Without --become the playbook will fail to run!
ansible-playbook -i inventory/mycluster/inventory.ini --limit third-node --become --become-user=root scale.yml -b -v

When the playbook is executed successfully, you can check if the third node is ready with following command:

kubectl get nodes

For more information, you can visit Kubespray document for adding/removing Kubernetes node.

How to config proxy?

If your nodes need proxy to access internet, you will need extra configurations during deploying K8s.

We assume your proxy is as below:

- http_proxy="http://proxy.fake-proxy.com:911"
- https_proxy="http://proxy.fake-proxy.com:912"

You can change parameters in inventory/mycluster/group_vars/all/all.yml to set http_proxy,https_proxy, and additional_no_proxy as following. Please make sure you’ve added all the nodes’ ip addresses into the additional_no_proxy parameter. In this example, we use 192.168.121.0/24 to represent all nodes’ ip addresses.

## Set these proxy values in order to update package manager and docker daemon to use proxies and custom CA for https_proxy if needed
http_proxy: "http://proxy.fake-proxy.com:911"
https_proxy: "http://proxy.fake-proxy.com:912"

## If you need exclude all cluster nodes from proxy and other resources, add other resources here.
additional_no_proxy: "localhost,127.0.0.1,192.168.121.0/24"