Create a LoadBalancer (as a Service)

A TCP-based load balancer for your upstreams

Overview

OpenStack provides load balancing through LoadBalancer as a Service (LBaaS).
This means that load balancing rules can be created directly within OpenStack.
No dedicated load balancer instance is required to use this service.

Prerequisites

• You should be able to use simple heat templates, like shown in the first steps tutorial.
• You know the basics of using the OpenStack CLI-Tools.
• Environment variables are set, like shown in the API-Access-Tutorial.

How to setup a TCP LoadBalancer

In this tutorial we demonstrate an LBaaS setup with the following features:

• a TCP load balancer
• Round Robin LB algorithm
• Health Monitor for LB pool members (upstream instances)
• a server group with dynamic number of servers
• every upstream node installs Apache2 and PHP7.0 FPM via HEAT
• "Anyapp" as simple PHP application

Clone git repository

We use a heat code example that we provide on Github.

git clone https://github.com/syseleven/heat-examples.git

Step one: Create the stack

Open the folder containing the example code and create the stack providing your SSH key and the stack name.

$ cd heat-examples/LBaaS

# openstack stack create -t lbstack.yaml --parameter key_name=<publicKeyName> <stackName>

$ openstack stack create -t lbstack.yaml --parameter key_name=exampleuser examplelb
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| id                  | f1ef864b-4acc-4e32-ac92-43c3551b794b |
| stack_name          | examplelb                            |
| description         | A Group of Load Balanced Servers     |
| creation_time       | 2018-03-01T10:03:48Z                 |
| updated_time        | None                                 |
| stack_status        | CREATE_IN_PROGRESS                   |
| stack_status_reason | Stack CREATE started                 |
+---------------------+--------------------------------------+

Step Two: Assign security group to load balancer

After a successful launch the whole setup will not be reachable from the outside until
you bind a valid security group to the load balancer port.

Ports can be assigned as follows:

openstack port set --security-group <Security Group> <LoadBalancer Port>

There is an output section that gives you the abilty to assign the correct security group to.

To simplify this process the example stack gives you a vaild openstack command in the output section.

openstack stack show <stackName> -f value -c outputs | grep -i 'port set'

Step Three: Check if the load balancer works properly

The example code contains the LB floating IP in its output:

# openstack stack show <stack name> -f value -c outputs

$ openstack stack show examplelb -f value -c outputs
[
  {
    "output_value": "http://195.192.128.20:80",
    "output_key": "lburl",
    "description": "This URL is the \"external\" URL that can be used to access the load balancer.\n"
  },
  {
    "output_value": "openstack port set --security-group 11764de3-3889-4be7-9627-3fb2e9431de1 447617cf-5818-4007-9909-ec3cf3fe4912",
    "output_key": "sec_group_connection",
    "description": "This command can be used to connect security groups to the  load balancer port. After the LB is accessible from the outside."
  }
]

To retrieve only the URL use the following command:

# openstack stack show <stack name> -f value -c outputs | grep -i 'http:' | cut -f2- -d:

$ openstack stack show examplelb -f value -c outputs | grep -i 'http:' | cut -f2- -d:

"http://195.192.128.20:80",

Open Anyapp in your browser via http://<loadbalancerIP> which shows the IP of the currently-used backend server.
Open Anyapp in other tabs/windows to see the load balancer working.

Conclusion

You should now be able to adopt this example to your needs.
The obvious things to change are the upstream servers, the overall architecture should work for many scenarios.