In our previous step we deployed a web app to Kubernetes on our Stack of NUCs.

Now we are going to install HAProxy.

Purpose:

• Demonstrate a using HAProxy in front of a web application on Kubernetes

References

• https://28gauravkhore.medium.com/how-to-configure-the-haproxy-using-the-ansible-and-also-how-to-configure-haproxy-dynamically-f18a55de3a66

From NUC 1, log in to the Ansible control node, NUC 2.

1. Create folder /home/ansible/my-project/haproxy and change directory to it
2. Copy the hosts file we created early in the lab
   • cp /home/ansible/my-project/hosts /home/ansible/my-project/haproxy/
3. Create the file /home/ansible/my-project/haproxy/ansible.cfg

   • ansible.cfg

     [defaults]
     inventory         = hosts

4. Create the file /home/ansible/my-project/haproxy/haproxy.cfg.j2

   • haproxy.cfg.j2

     # ------------------------
     # main frontend which proxys to the backends
     # ------------------------
     frontend main
         bind *:8080
         acl url_static  path_beg    -i /static /images /javascript /stylesheets
         acl url_static  path_end    -i .jpg .gif .png .css .js
      
         use_backend static  if url_static
         default_backend app
     # ------------------------
     # static backend for serving up images, stylesheets and such
     # ------------------------
     backend static
         balance roundrobin
         server  static 127.0.0.1:4331 check
     # ------------------------
     # round robin balancing between the various backends
     # ------------------------
     backend app
         balance roundrobin
     {% for ip in groups['nodes'] %}
         server app{{ loop.index}} {{ ip }}:80 check
     {% endfor %}

haproxy-install.yml

---
- hosts: nodes
  tasks:
    - name: Install haproxy
      package:
        name: haproxy
        state: present
    - name: Configure haproxy.cfg file
      template:
        src: "/home/ansible/my-project/haproxy/haproxy.cfg.j2"
        dest: "/etc/haproxy/haproxy.cfg"
    - name: "haproxy service start"
      service:
        name: haproxy
        state: restarted

ansible-playbook haproxy-install.yml

1. Point your browser to http://IPANYK8WORKER:8080/
2. Let's prove that any of the nodes will serve the app from any pod on any host
   • Change directory to /home/ansible/my-project/k8s
   • Edit speedtester-deployment.yml and change the number of replicas to 1
   • kubectl apply -f speedtester-deployment.yml
   • Use kubectl get pows to watch the pods terminated until 1 is left running
   • Point your browser to any of the k8s working IPs on port 8080 and note the app is still up
   • Set the replicas back to equal the number of worker nodes and apply the file again