Creating a Basic Elastic Load Balancing Configuration

Elastic load balancing requires two basic elements to function properly: a load balancer and instances registered with that load balancer. The following examples show how to set up the basic elements of an elastic load balancer configuration.

Create a Load Balancer

The load balancer manages incoming traffic, and monitors the health of your instances. The load balancer ensures that traffic is only sent to healthy instances.

To create a load balancer:

Enter the following command, specifying availability zones:

eulb-create-lb -z one -l "lb-port=80, protocol=HTTP, instance-port=80, 
instance-protocol=HTTP" MyLoadBalancer

To verify the elastic load balancer has been created, enter the following command:
eulb-describe-lbs MyLoadBalancer
You should see output similar to the following:
```
LOAD_BALANCER	MyLoadBalancer	MyLoadBalancer-587773761872.lb.localhost	2013-01-01T01:23:45.678Z
```

Optionally, you can create listeners for the load balancer as follows:

eulb-create-lb-listeners --listener "lb-port=80, protocol=HTTP,
    instance-port=80, instance-protocol=HTTP"

You've now created an elastic load balancer.

Register instances with the Load Balancer

The load balancer monitors the health of registered instances, and balances incoming traffic across the healthy instances.

To register an instance with the load balancer:

Enter the following command:

eulb-register-instances-with-lb --instances i-e0636aca,i-0c9c3967 MyLoadBalancer

Enter the following command to verify that the instances are registered with the load balancer:
eulb-describe-instance-health MyLoadBalancer
This command will return output similar to the following:
```
INSTANCE	i-6FAD3F7B	InService
INSTANCE	i-70FE4541	InService
```

Once you've created the load balancer and registered your instances with it, the load balancer will automatically route traffic from its endpoint URL to healthy instances.

Parent topic: Eucalyptus Load Balancing Usage Examples