In order to provide continuous availability and high availability (HA), load balancing with Varnish requires the configuration of several instances of Varnish within a cluster. This is done in order to distribute incoming traffic. This is how you can accomplish this goal:

Deploy Multiple Servers of Varnish

Make use of a number of different physical or virtual machines to set up several Varnish servers. In your Varnish cluster, these servers will fulfil the role of nodes.

Configure Varnish Instance

Ensure that each server has the same configurations for Varnish, and then install and configure it. Its imperative that every instance of Varnish, set up is to independently manage requests.

Implement Load Balancing into Account

To uniformly distribute incoming traffic across all Varnish instances, use a load balancer like HAProxy or Nginx.

Varnish servers should undergo health checks, and the load balancer should direct traffic to servers that are in good health.

Persistence of the Session

If your application requires session persistence, ensure that you configure the load balancer to use sticky sessions. Sticky sessions ensure that Varnish always directs requests from the same client to the same server.

Shared Storage 

For increased resilience, you can store the contents of the Varnish cache on shared storage, such as the Network File System (NFS) or a distributed file system. We guarantee consistency of the cache contents across all Varnish instances in the cluster.

Monitor and manage cluster

Ensure that your Varnish cluster is in good health and performing well. Monitor several metrics such as response times, cache hit rates, and server utilisation.

If you want to detect and deal with server problems, you need implement automated failover systems. It is possible that this will involve automatically removing broken servers from the load balancer pool and transferring traffic to servers that are in good health.

HAProxy Configuration

frontend http_front
    bind *:80 
    mode http
    default_backend varnish_back

backend varnish_back
    mode http
    balance roundrobin
    option http-server-close
    option forwardfor
    server varnisha 192.168.1.111:6081 check
    server varnishb 192.168.1.112:6081 check
    server varnishc 192.168.1.113:6081 check

HTTP_front listens on port 80 for HTTP requests.Varinish’s backend configuration, varnish_back, load balances traffic across several servers.Servers in Varnish have IP addresses and ports (usually 6081 for administrative interface).

Health checks are performed (check directive) to ensure that only healthy Varnish servers receive traffic.

Take care to test the high availability setup for server failures and continued service.To accommodate traffic and server infrastructure changes, examine and update the configuration regularly.

Whether you need to ensure consistent uptime or distribute traffic effectively, Skynats’ team can optimize your setup for peak performance. Contact Skynats today to enhance your high availability and load balancing with their specialized Varnish services.