Load balancer

A load balancer distributes incoming traffic across multiple virtual machines so no single VM is overwhelmed. On American Cloud, load balancing is configured as a set of load balancer rules attached to a public IP — there is no separate "Load Balancer" resource. Each rule maps a public port on the IP to a private port on one or more backend VMs.

Prerequisites

Before you create a rule, you need:

• At least two VMs running the same application. See Cloud Compute.
• A public IP allocated to the network those VMs are attached to.

Add a load balancer rule

1. In the left navigation, under Networking, select Public IPs.

2. Click the public IP you want to load-balance traffic on.
3. Scroll to the Load Balancer Rules section and click + Add Rule.
4. In the Add Load Balancer Rule dialog, fill in the fields:
   • Name — a unique name for the rule (for example, web-https).
   • Algorithm — how traffic is distributed across backends. Round Robin is the default.
   • Public port — the port clients connect to on the public IP (for example, 443).
   • Private port — the port on the backend VMs that receives the traffic (for example, 443).
   • Protocol — TCP or UDP.
5. Click Add Rule.

The new rule appears in the Load Balancer Rules list.

Attach VMs to a rule

A rule does nothing until you tell it which VMs to send traffic to.

1. Find the rule in the Load Balancer Rules list and click VMs.
2. Select the VMs that should receive traffic for this rule.
3. Save.

The selected VMs show up in the Instances column on the rule's row.

Manage rules

Each rule row has three actions:

• Edit — change name, algorithm, ports, or protocol.
• VMs — change which backends receive traffic.
• Delete — remove the rule.

Rule state

The State column shows the current status of each rule. A rule must be ACTIVE to serve traffic.

If a rule is not active, check that at least one VM is attached and that the protocol and ports match what the application is listening on.