The Abiquo API can be balanced amongst several servers to spread load and increase service capacity. As you know, Abiquo provides an HTML5 client application that runs on your browser that interacts with the API to operate the cloud.

So, as the UI is a regular HTML app, there may be several options to balance both the UI and the API. A couple of examples are given below.

API plus UI cluster

In this setup, we are spreading the load amongst a cluster of nodes running both API and UI. Please note that any API clustered setup REQUIRES using zookeeper to work.
For the sake of simplicity, we are using a two node setup, but this is easily scalable to several nodes and using Apache web server as a load balancer.

 CHANGE THIS

Assume the following IP addressing for our cluster nodes.

Installation

Start by installing backend severs using the Server profile of the Abiquo ISO installer. This profile will install API and UI webapps, as well as the zookeeper daemon needed for API to work in a clustered configuration.

Once you have both servers with the Server profile installed, keep in mind that you need to keep abiquo.properties file synchronized on every node in the API cluster.

API consensus

First, for the API to function as a clustered API, you need to setup Zookeeper. You may want to run Zookeeper in the LoadBalancer node or in a separate box, depending in your needs and/or preferences.
Zookeeper requires JVM to run, ensure that JVM (Oracle or OpenJDK) is installed.

# java -v

The zookeeper package is installed using the "Server" profile of the Abiquo installer ISO. If it is not installed, you can do so typing:

# yum -y install zookeeper

Then, you need to add the following line in the [server] section of the abiquo.properties file in all Abiquo API server nodes:

abiquo.api.zk.serverConnection = <zookeeper_ip>:2181

Replace <zookeeper_ip> to match your environment. Also, add or modify the abiquo.server.api.location property to match the load balancer URL for the API service (shown below):

abiquo.server.api.location = https://abiquo.example.com/api

You will need to edit file /opt/abiquo/tomcat/conf/Catalina/localhost/api.xml and /opt/abiquo/tomcat/conf/Catalina/localhost/m.xml and set the values for the MySQL kinton database connection:

<Resource name="jdbc/abiquoDB" auth="Container" type="javax.sql.DataSource" initialSize="10" suspectTimeout="60" timeBetweenEvictionRunsMillis="30000" minEvictableIdleTimeMillis="60000" maxActive="100" minIdle="10" maxIdle="50" maxWait="10000" removeAbandoned="true" removeAbandonedTimeout="60" logAbandoned="true" username="mysql_user" password="user_password" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://mysql.example.com:3306/kinton?autoReconnect=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>

You need to change the url, username and password attributes to match your environment.

UI configuration

In a clustered UI setup, you will need to configure the LB as API endpoint for each UI node. Edit /var/www/html/ui/config/client-config.json file and set same config.endpoint property for each UI node. For example:

"config.endpoint": "https://abiquo.example.com/api"

LoadBalancer Apache node configuration

You need to make sure that Apache's required modules are loaded. Be sure to include the following lines in your Apache config file:

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule proxy_connect_module modules/mod_proxy_connect.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so

In the LoadBalancer node running Apache, create a new config file in /etc/httpd/conf.d/api-balancer.conf with the following contents:

<VirtualHost *:443>
	ServerName abiquo.example.com
	SSLEngine on
	SSLProtocol all -SSLv2
	SSLCipherSuite ALL:!ADH:!EXPORT:!SSLv2:RC4+RSA:+HIGH:+MEDIUM:+LOW
	SSLCertificateFile /etc/pki/tls/certs/abiquo.example.com.crt
	SSLCertificateKeyFile /etc/pki/tls/private/abiquo.example.com.key
	# Enable the balancer manager console in the server root
	<Location />
		SetHandler balancer-manager
	</Location>
	# Configure the API AJP cluster nodes
	<Proxy balancer://api-cluster>
		BalancerMember ajp://192.168.2.100:8010 route=node1 ping=1
		BalancerMember ajp://192.168.2.101:8010 route=node2 ping=1
	</Proxy>
	# Configure the UI HTTP cluster nodes
	<Proxy balancer://ui-cluster>
		BalancerMember http://192.168.2.100 route=node1 ping=1
		BalancerMember http://192.168.2.101 route=node2 ping=1
	</Proxy>
	# Configure the modules we want to load balance
	ProxyPass /api/			balancer://api-cluster/api/
	ProxyPass /ui/			balancer://ui-cluster/ui/ stickysession=JSESSIONID|jsessionid
</VirtualHost>

Restart or reload your Apache server to apply new configuration.

Abiquo API Tomcat configuration

<Engine name="Catalina" defaultHost="localhost" jvmRoute="node1">

# echo -n | openssl s_client -connect abiquo.example.com:443 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > abiquo.example.com.cert
# /usr/java/default/bin/keytool -import -file abiquo.example.com.cert -keystore /path/to/cacerts
# /usr/java/default/bin/keytool -import -trustcacerts -file /path/to/ca/ca.pem -alias CA_ALIAS -keystore /path/to/cacerts

Restart tomcat after the change to apply new configuration.

Now, accessing your balancer IP at https://abiquo.example.com/ui/ or https://abiquo.example.com/api/, will balance requests between the two backend nodes.

# curl -k -u admin:xabiquo --silent -X GET https://abiquo.example.com/api/login

{"links":[{"title":"Abiquo","rel":"enterprise","type":"application/vnd.abiquo.enterprise+json","href":"https://abiquo.example.com:443/api/admin/enterprises/1"},{"title":"CLOUD_ADMIN","rel":"role","type":"application/vnd.abiquo.role+json","href":"https://abiquo.example.com:443/api/admin/roles/1"},{"title":"CLOUD_ADMIN","rel":"edit","type":"application/vnd.abiquo.user+json","href":"https://abiquo.example.com:443/api/admin/enterprises/1/users/1"},{"title":"virtual machines","rel":"virtualmachines","type":"application/vnd.abiquo.virtualmachines+json","href":"https://abiquo.example.com:443/api/admin/enterprises/1/users/1/action/virtualmachines"},{"title":"pending tasks","rel":"pendingtasks","type":"application/vnd.abiquo.tasks+json","href":"https://abiquo.example.com:443/api/admin/enterprises/1/users/1/action/pendingtasks"},{"title":"applications","rel":"applications","type":"application/vnd.abiquo.applications+json","href":"https://abiquo.example.com:443/api/admin/enterprises/1/users/1/applications"}],"id":1,"name":"Cloud","nick":"admin","locale":"en_US","surname":"Administrator","active":true,"email":"","description":"Main administrator","authType":"ABIQUO"}