In our previous step we deployed our fleet of VMs.

Now we are going to install Kubernetes on the VMs:

• The first will be the Kubernetes (k8s) master node
• The second will be the node running the SQL service
• The remaining VMs will be the “worker” nodes

Purpose:

• Demonstrate a running a complex workload of web applications on Kubernetes

References

• Kubernetes: Up & Running by O'Reilly
• https://github.com/brettplarson/nuctestlab
• https://www.linuxtechi.com/install-kubernetes-on-ubuntu-22-04/
• https://github.com/torgeirl/kubernetes-playbooks

Modify the inventory file to assign nodes to groups. Here is an example assigning my server IPs to each group.

inventory

[master]
192.168.99.201
[sql]
192.168.99.202
[workers]
192.168.99.203
192.168.99.204

Configure ansible.cfg to use the inventory file

ansible.cfg

[defaults]
inventory         = inventory

Update the /etc/hosts files with the hostnames. This allows all nodes to resolve each other by name, but without DNS

updatehostsfile.yml

---
- name: Update etc/hosts file
  hosts: all, localhost
  gather_facts: true
  tasks:
    - name: Populate all /etc/hosts files
      tags: etchostsupdate
      become: true
      become_user: root
      lineinfile:
        path: "/etc/hosts"
        regexp: '.*{{ item }}$'
        line: "{{ hostvars[item]['ansible_default_ipv4'].address }}\t{{ hostvars[item]['ansible_hostname'] }}\t{{ hostvars[item]['ansible_hostname'] }}"
        state: present
      with_items: '{{ groups.all }}'

Run the playbook, providing the ansible user password you set when prompted.

ansible-playbook updatehostsfile.yml --ask-become

Note that you can now run an ansible “ping” with simply ansible all -m ping

Check https://github.com/torgeirl/kubernetes-playbooks for updates to the playbooks below

1. Install some prerequisites on ALL the Kubernetes nodes

   • kube-dependencies.yml

     ---
     - hosts: all
       become: true
       tasks:
         - fail:
             msg: "OS should be Ubuntu 22.04, not {{ ansible_distribution }} {{ ansible_distribution_version }}"
           when: ansible_distribution != 'Ubuntu' or ansible_distribution_version != '22.04'
     
         - name: Update APT packages
           apt:
             update_cache: true
     
         - name: Reboot and wait for reboot to complete
           reboot:
     
         - name: Disable SWAP (Kubeadm requirement)
           shell: |
             swapoff -a
     
         - name: Disable SWAP in fstab (Kubeadm requirement)
           replace:
             path: /etc/fstab
             regexp: '^([^#].*?\sswap\s+sw\s+.*)$'
             replace: '# \1'
     
         - name: Create an empty file for the Containerd module
           copy:
             content: ""
             dest: /etc/modules-load.d/containerd.conf
             force: false
     
         - name: Configure modules for Containerd
           blockinfile:
             path: /etc/modules-load.d/containerd.conf
             block: |
                  overlay
                  br_netfilter
     
         - name: Create an empty file for Kubernetes sysctl params
           copy:
             content: ""
             dest: /etc/sysctl.d/99-kubernetes-cri.conf
             force: false
     
         - name: Configure sysctl params for Kubernetes
           lineinfile:
             path: /etc/sysctl.d/99-kubernetes-cri.conf
             line: "{{ item }}"
           with_items:
             - 'net.bridge.bridge-nf-call-iptables  = 1'
             - 'net.ipv4.ip_forward                 = 1'
             - 'net.bridge.bridge-nf-call-ip6tables = 1'
     
         - name: Apply sysctl params without reboot
           command: sysctl --system
     
         - name: Install APT Transport HTTPS
           apt:
             name: apt-transport-https
             state: present
     
         - name: Add Docker apt-key
           apt_key:
             url: https://download.docker.com/linux/ubuntu/gpg
             state: present
     
         - name: Add Docker's APT repository
           apt_repository:
             repo: "deb [arch=amd64] https://download.docker.com/linux/ubuntu {{ ansible_distribution_release }} stable"
             filename: "docker-{{ ansible_distribution_release }}"
     
         - name: Add Kubernetes apt-key
           apt_key:
             url: https://packages.cloud.google.com/apt/doc/apt-key.gpg
             state: present
     
         - name: Add Kubernetes' APT repository
           apt_repository:
             repo: deb https://apt.kubernetes.io/ kubernetes-xenial main
             state: present
             filename: 'kubernetes'
     
         - name: Install Containerd
           apt:
             name: containerd.io
             state: present
     
         - name: Create Containerd directory
           file:
             path: /etc/containerd
             state: directory
     
         - name: Add Containerd configuration
           shell: /usr/bin/containerd config default > /etc/containerd/config.toml
     
         - name: Configuring the systemd cgroup driver for Containerd
           lineinfile:
             path: /etc/containerd/config.toml
             regexp: '            SystemdCgroup = false'
             line: '            SystemdCgroup = true'
     
         - name: Enable the Containerd service and start it
           systemd:
             name: containerd
             state: restarted
             enabled: true
             daemon-reload: true
     
         - name: Install Kubelet
           apt:
             name: kubelet=1.26.*
             state: present
             update_cache: true
     
         - name: Install Kubeadm
           apt:
             name: kubeadm=1.26.*
             state: present
     
         - name: Enable the Kubelet service, and enable it persistently
           service:
             name: kubelet
             enabled: true
     
         - name: Load br_netfilter kernel module
           modprobe:
             name: br_netfilter
             state: present
     
         - name: Set bridge-nf-call-iptables
           sysctl:
             name: net.bridge.bridge-nf-call-iptables
             value: 1
     
         - name: Set ip_forward
           sysctl:
             name: net.ipv4.ip_forward
             value: 1
     
         - name: Check Kubelet args in Kubelet config
           shell: grep "^Environment=\"KUBELET_EXTRA_ARGS=" /etc/systemd/system/kubelet.service.d/10-kubeadm.conf || true
           register: check_args
      
         - name: Add runtime args in Kubelet config
           lineinfile:
             dest: "/etc/systemd/system/kubelet.service.d/10-kubeadm.conf"
             line: "Environment=\"KUBELET_EXTRA_ARGS= --runtime-cgroups=/system.slice/containerd.service --container-runtime-endpoint=unix:///run/containerd/containerd.sock\""
             insertafter: '\[Service\]'
           when: check_args.stdout == ""
      
         - name: Reboot and wait for reboot to complete
           reboot:
      
     - hosts: master
       become: true
       tasks:
         - name: Install Kubectl
           apt:
             name: kubectl=1.26.*
             state: present
             force: true  # allow downgrades

2. Run ansible-playbook kube-dependencies.yml
3. Configure kubernetes cluster on master node

   • master.yml

     ---
     - hosts: master
       become: true
       tasks:
         - name: Create an empty file for Kubeadm configuring
           copy:
             content: ""
             dest: /etc/kubernetes/kubeadm-config.yaml
             force: false
     
         - name: Configuring the container runtime including its cgroup driver
           blockinfile:
             path: /etc/kubernetes/kubeadm-config.yaml
             block: |
                  kind: ClusterConfiguration
                  apiVersion: kubeadm.k8s.io/v1beta3
                  networking:
                    podSubnet: "10.244.0.0/16"
                  ---
                  kind: KubeletConfiguration
                  apiVersion: kubelet.config.k8s.io/v1beta1
                  runtimeRequestTimeout: "15m"
                  cgroupDriver: "systemd"
                  systemReserved:
                    cpu: 100m
                    memory: 350M
                  kubeReserved:
                    cpu: 100m
                    memory: 50M
                  enforceNodeAllocatable:
                  - pods
     
         - name: Initialize the cluster (this could take some time)
           shell: kubeadm init --config /etc/kubernetes/kubeadm-config.yaml >> cluster_initialized.log
           args:
             chdir: /home/ansible
             creates: cluster_initialized.log
     
         - name: Create .kube directory
           become: true
           become_user: ansible
           file:
             path: $HOME/.kube
             state: directory
             mode: 0755
     
         - name: Copy admin.conf to user's kube config
           copy:
             src: /etc/kubernetes/admin.conf
             dest: /home/ansible/.kube/config
             remote_src: true
             owner: ansible
     
         - name: Install Pod network
           become: true
           become_user: ansible
           shell: kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yml >> pod_network_setup.log
           args:
             chdir: $HOME
             creates: pod_network_setup.log

   • run ansible-playbook master.yml
4. SSH to the master and verify the master nodes gets status Ready
   • ssh controller kubectl get nodes

Modify the file to replace MASTERIP with the IP address of your master node in two (2) places

• sql.yml

  ---
  - hosts: master
    become: true
    # gather_facts: false
    tasks:
      - name: Get join command
        shell: kubeadm token create --print-join-command
        register: join_command_raw
  
      - name: Set join command
        set_fact:
          join_command: "{{ join_command_raw.stdout_lines[0] }}"
  
  - hosts: sql
    become: true
    tasks:
      - name: TCP port 6443 on master is reachable from worker
        wait_for: "host={{ 'MASTERIP' }} port=6443 timeout=1"
  
      - name: Join cluster
        shell: "{{ hostvars['MASTERIP'].join_command }} >> node_joined.log"
        args:
          chdir: /home/ansible
          creates: node_joined.log

Run the playbook: ansible-playbook sql.yml

1. SSH to the master and verify all the nodes return status Ready
   • ssh controller kubectl get nodes

Modify the file to replace MASTERIP with the IP address of your master node in two (2) places

• workers.yml

  ---
  - hosts: master
    become: true
    # gather_facts: false
    tasks:
      - name: Get join command
        shell: kubeadm token create --print-join-command
        register: join_command_raw
  
      - name: Set join command
        set_fact:
          join_command: "{{ join_command_raw.stdout_lines[0] }}"
  
  - hosts: workers
    become: true
    tasks:
      - name: TCP port 6443 on master is reachable from worker
        wait_for: "host={{ 'MASTERIP' }} port=6443 timeout=1"
  
      - name: Join cluster
        shell: "{{ hostvars['MASTERIP'].join_command }} >> node_joined.log"
        args:
          chdir: /home/ansible
          creates: node_joined.log

Run the playbook: ansible-playbook workers.yml

1. SSH to the master and verify all the nodes return status Ready
   • ssh controller kubectl get nodes

Install kubectl on the host (the Ansible controller) to allow for automation with Kubernetes

create file /home/ansible/kubectlcontrolnode.yml

kubectlcontrolnode.yml

---
- hosts: localhost
  become: true
  gather_facts: false
  tasks:
    - name: Update APT packages
      apt:
        update_cache: true

    - name: Add Kubernetes apt-key
      apt_key:
        url: https://packages.cloud.google.com/apt/doc/apt-key.gpg
        state: present

    - name: Add Kubernetes' APT repository
      apt_repository:
        repo: deb https://apt.kubernetes.io/ kubernetes-xenial main
        state: present
        filename: 'kubernetes'

    - name: Install Kubectl
      apt:
        name: kubectl=1.26.*
        state: present
        force: true  # allow downgrades

Run the playbook and enter the password for the user ansible when prompted.

ansible-playbook kubectlcontrolnode.yml --ask-become

Running kubectl version will fail at this point because you don't have credentials

Copy credentials

• scp -r controller:/home/ansible/.kube ~/

Confirm it's working now by running

• kubectl version
• kubectl get nodes

Continue to Step 4 - SQL Server

Or back to Step 2 - Deploy the VMs or Start.