Rackspace Cloud Load Balancer

Note: This document assumes that the reader is familiar with HOT specification. If that is not the case, please go to the References section listed at the end of this tutorial for HOT specification link.

Brief summary

A load balancer is used to distribute workloads between multiple back-end systems or services based on the criteria defined as part of its configuration.

Example load balancer template

A simple load balancer template is listed below.

heat_template_version: 2014-10-16

description: |
  Creating Rackspace cloud loadbalancer using orchestration service.

resources:
  api_loadbalancer:
    type: Rackspace::Cloud::LoadBalancer
    properties:
      name: test_load_balancer
      metadata:
        rax-heat: { get_param: "OS::stack_id" }
      protocol: HTTPS
      port: 80
      algorithm: ROUND_ROBIN
      nodes: []
      virtualIps:
      - type: SERVICENET
        ipVersion: IPV4

Load balancer properties

The complete list of load balancer properties that can be provided to the resource follows.

accessList: {Type: CommaDelimitedList}
algorithm:
  AllowedValues: [LEAST_CONNECTIONS, RANDOM, ROUND_ROBIN, WEIGHTED_LEAST_CONNECTIONS,
    WEIGHTED_ROUND_ROBIN]
  Type: String
connectionLogging:
  AllowedValues: ['True', 'true', 'False', 'false']
  Type: Boolean
connectionThrottle: {Type: Json}
contentCaching:
  AllowedValues: [ENABLED, DISABLED]
  Type: String
errorPage: {Type: String}
halfClosed:
  AllowedValues: ['True', 'true', 'False', 'false']
  Type: Boolean
healthMonitor: {Type: Json}
httpsRedirect:
  AllowedValues: ['True', 'true', 'False', 'false']
  Default: false
  Description: Enables or disables HTTP to HTTPS redirection for the load balancer.
    When enabled, any HTTP request returns status code 301 (Moved Permanently),
    and the requester is redirected to the requested URL via the HTTPS protocol
    on port 443. Only available for HTTPS protocol (port=443), or HTTP protocol
    with a properly configured SSL termination (secureTrafficOnly=true, securePort=443).
  Type: Boolean
metadata: {Type: Json}
name: {Type: String}
nodes:
  Type: CommaDelimitedList
  Required: True
port:
  Type: Number
  Required: True
protocol:
  AllowedValues: [DNS_TCP, DNS_UDP, FTP, HTTP, HTTPS, IMAPS, IMAPv4, LDAP, LDAPS,
    MYSQL, POP3, POP3S, SMTP, TCP, TCP_CLIENT_FIRST, UDP, UDP_STREAM, SFTP]
  Type: String
  Required: True
sessionPersistence:
  AllowedValues: [HTTP_COOKIE, SOURCE_IP]
  Type: String
sslTermination: {Type: Json}
timeout: {MaxValue: 120, MinValue: 1, Type: Number}
virtualIps:
  MinLength: 1
  Type: CommaDelimitedList
  Required: True

Example template with load balancer

In the following example template, we will create a multi node WordPress application with two Linux servers, one Trove (DBaaS) instance, and one load balancer.

First add a database instance resource (OS::Trove::Instance) to the template.

heat_template_version: 2014-10-16

description: |
  Creating Rackspace cloud server with user_data.

resources:
  db:
    type: OS::Trove::Instance
    properties:
      name: wordpress
      flavor: 1GB Instance
      size: 30
      users:
      - name: admin
        password: admin
        databases:
        - wordpress
      databases:
      - name: wordpress

This template creates a database instance with the name wordpress and admin as the username and password.

Now add two server resources and install WordPress application.

heat_template_version: 2014-10-16

description: |
  Creating Rackspace cloud server with SSH access private key.

resources:
  web_nodes:
    type: OS::Heat::ResourceGroup
    properties:
      count: 2
      resource_def:
        type: "OS::Nova::Server"
        properties:
          name: test-server
          flavor: 2 GB General Purpose v1
          image: Debian 7 (Wheezy) (PVHVM)
          user_data:
            str_replace:
              template: |
                #!/bin/bash -v
                yum -y install mysql-server httpd wordpress
                sed -i "/Deny from All/d" /etc/httpd/conf.d/wordpress.conf
                sed -i "s/Require local/Require all granted/" /etc/httpd/conf.d/wordpress.conf
                sed --in-place --e "s/localhost/%dbhost%/" --e "s/database_name_here/%dbname%/" --e "s/username_here/%dbuser%/" --e "s/password_here/%dbpass%/" /usr/share/wordpress/wp-config.php
                /etc/init.d/httpd start
                chkconfig httpd on
                /etc/init.d/mysqld start
                chkconfig mysqld on
                cat << EOF | mysql
                CREATE DATABASE %dbname%;
                GRANT ALL PRIVILEGES ON %dbname%.* TO "%dbuser%"@"localhost"
                IDENTIFIED BY "%dbpass%";
                FLUSH PRIVILEGES;
                EXIT
                EOF
                iptables -I INPUT -p tcp --dport 80 -j ACCEPT
                iptables-save > /etc/sysconfig/iptables
              params:
                "%dbhost%": { get_attr: [ db, hostname ] }
                "%dbname%": wordpress
                "%dbuser%": admin
                "%dbpass%": admin
  db:
    type: OS::Trove::Instance
    properties:
      name: wordpress
      flavor: 1GB Instance
      size: 30
      users:
      - name: admin
        password: admin
        databases:
        - wordpress
      databases:
      - name: wordpress

Here a ResourceGroup of type ‘OS::Nova::Server’ is added to the template. The user_data property contains a script to install the WordPress application. Please note that database instance hostname information is passed to the script.

Finally, add the load balancer resource and provide the server addresses to the load balancer. Given below is the complete template that can be used to create a load balanced multi node WordPress application.

Full Template

heat_template_version: 2014-10-16

description: |
  Create a loadbalanced two node wordpress application.

resources:
  lb:
    type: "Rackspace::Cloud::LoadBalancer"
    properties:
      name: wordpress_loadbalancer
      nodes:
      - addresses: { get_attr: [ web_nodes, privateIPv4 ] }
        port: 80
        condition: ENABLED
      protocol: HTTP
      halfClosed: False
      algorithm: LEAST_CONNECTIONS
      connectionThrottle:
        maxConnections: 50
        minConnections: 50
        maxConnectionRate: 50
        rateInterval: 50
      port: 80
      timeout: 120
      sessionPersistence: HTTP_COOKIE
      virtualIps:
      - type: PUBLIC
        ipVersion: IPV4
      healthMonitor:
        type: HTTP
        delay: 10
        timeout: 10
        attemptsBeforeDeactivation: 3
        path: "/"
        statusRegex: "."
        bodyRegex: "."
      contentCaching: ENABLED

  web_nodes:
    type: OS::Heat::ResourceGroup
    properties:
      count: 2
      resource_def:
        type: "OS::Nova::Server"
        properties:
          name: test-server
          flavor: 2 GB General Purpose v1
          image: Debian 7 (Wheezy) (PVHVM)
          user_data:
            str_replace:
              template: |
                #!/bin/bash -v
                yum -y install mysql-server httpd wordpress
                sed -i "/Deny from All/d" /etc/httpd/conf.d/wordpress.conf
                sed -i "s/Require local/Require all granted/" /etc/httpd/conf.d/wordpress.conf
                sed --in-place --e "s/localhost/%dbhost%/" --e "s/database_name_here/%dbname%/" --e "s/username_here/%dbuser%/" --e "s/password_here/%dbpass%/" /usr/share/wordpress/wp-config.php
                /etc/init.d/httpd start
                chkconfig httpd on
                /etc/init.d/mysqld start
                chkconfig mysqld on
                cat << EOF | mysql
                CREATE DATABASE %dbname%;
                GRANT ALL PRIVILEGES ON %dbname%.* TO "%dbuser%"@"localhost"
                IDENTIFIED BY "%dbpass%";
                FLUSH PRIVILEGES;
                EXIT
                EOF
                iptables -I INPUT -p tcp --dport 80 -j ACCEPT
                iptables-save > /etc/sysconfig/iptables
              params:
                "%dbhost%": { get_attr: [ db, hostname ] }
                "%dbname%": wordpress
                "%dbuser%": admin
                "%dbpass%": admin
  db:
    type: OS::Trove::Instance
    properties:
      name: wordpress
      flavor: 1GB Instance
      size: 30
      users:
      - name: admin
        password: admin
        databases:
        - wordpress
      databases:
      - name: wordpress

outputs:
  wordpress_url:
    value:
      str_replace:
        template: "http://%ip%/wordpress"
        params:
          "%ip%": { get_attr: [ lb, PublicIp ] }
    description: Public URL for the wordpress blog

Please note that to keep the template simple, all the values were hard coded in the above template.

Reference

• Cloud Orchestration API Developer Guide

• Heat Orchestration Template (HOT) Specification

• Cloud Load Balancer Getting Started guide

• Cloud Load Balancer API Developer Guide