jcborras/pomaloba

The poor man's Load Balancing solution (for bare-metal Kubernetes setups)

Pomaloba

The Poor man's Load Balancer (ie. for bare-metal Kubernetes clusters)

Quick example

cat << EOF > sample.json
{
  "pomaloba": 1,
  "app": "MyApp",
  "endpoints": [ 
    {"ip": "1.2.3.4", "port": 1234 }
  ],
  "destinations": [
    {"ip": "192.168.100.11", "port": 31234 },
    {"ip": "192.168.100.12", "port": 31234 },
    {"ip": "192.168.100.13", "port": 31234 },
    {"ip": "192.168.100.14", "port": 31234 }
  ]
}
EOF

pomaloba --input-spec sample.json

Motivation

Let's say you have your own bare-metal Kubernetes cluster running on your private cloud or even realized using several VM instances merrily running in your own desktop (or laptop these days).

Everything is fine until you deploy a workload consisting in several replicas and want to add a Load Balancer to the mix: A Service of type Load Balancer won't deploy. What do you do now?

Well you could use Services of type NodePort ensuring the traffic will arrive to its destination once you reach the worker nodes but you still want to have a single (IP address, port) endpoint to reach your application.

Thus this Poor Man's Load Balancer exists: just provision a small VM instance with Linux NetFilter enabled and use the Pomaloba output o generate the necesary DNAT and Masquerading actions to make it happen.

For the time being it generates output suitable to be used by iptables but supporting nftables and Ansible should not be too complicated once I wrap my head around it.