Creating a Web Cluster with LXD

Take a snapshot of the container:

lxc snapshot web01 1.0

We now want to create four web## containers based on this snapshot. We can do this manually by running lxc copy web/1.0 web## for each container, or by using a Bash script:

vim /tmp/container-script.sh

containers="web02 web03 web04 web05"

for c in $containers
do
	lxc copy web01/1.0 $c
	lxc start $c
done

sh /tmp/container-script.sh

Confirm:

lxc list

Create a lb01 container, also based on the existing web01/1.0 snapshot:

lxc copy web01/1.0 lb01
lxc start lb01

Open and edit the /etc/nginx/conf.d/default.conf file, and set up the load balancer. Remember that host records are set up between containers, so we can use the container names here:

lxc file edit lb01/etc/nginx/conf.d/default.conf

upstream lb {
        server web01;
        server web02;
        server web03;
        server web04;
        server web05;
}

server {
        listen 80 default_server;
        listen [::]:80 default_server;

        location / {
                proxy_pass http://lb;
        }

}

Restart nginx:

lxc exec lb01 -- rc-service nginx restart

Test that we can access the website using curl and the IP of the load balancer:

lxc list
curl <lb_ip>

Ensure that when the host's IP is accessed, it forwards to the load balancer container:

sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to <lb_ip>:80

Navigate to the public IP of your server in your browser to ensure the load balancer works.