Load Balancing Variables¶
As part of the process of configuring the deployment in an environment, you can define a set of scripts that disable and enable a Virtual DataPort server or an entire cluster in the load balancer. These scripts can receive two kind of parameters: literal values or load balancing variables.
Load balancing variables are user-defined variables that can be assigned to Virtual DataPort servers or clusters. Thus, if your script depends on a cluster load balancing variable, you have to give a value to that variable for each cluster of the environment. In the same way, if it depends on a server load balancing variable, you should assign a value to that variable for every Virtual DataPort server that belongs to the environment. When the Solution Manager executes the script, it will use the corresponding value of the load balancing variable, according to which server or cluster it is updating.
Take into account that the scripts that enable or disable clusters in the load balancer can only receive cluster load balancing variables as parameters. Nevertheless, those scripts that enable or disable servers in the load balancer can receive both cluster and server load balancing variables.
There are some load balancing variables that are automatically created for every server: name, host and port. Their value corresponds to the field with the same name in the server definition dialog. These predefined load balancing variables cannot be deleted or modified.
Let’s see an example with a cluster “Cluster 1”, with the IP address 192.168.0.1, and a server “Server 1” defined inside the cluster, with the IP 192.168.0.10.
You can define the load balancing variable ClusterIP, which applies to clusters, and assign it the value 192.168.0.1 for the cluster of the example.
In the deployment configuration, you can define the script that disables servers
in the load balancer as
disable_server_from_load_balancer.sh <clusterIP> <host>,
host is the predefined load balancing variable and
the cluster load balancing variable that you have created.
During the deployment, the Solution Manager executes the script with the appropriate arguments, using the values of the load balancing variables assigned to the current server and its cluster, as follows:
$ disable_server_from_load_balancer.sh 192.168.0.1 192.168.0.10
Remember that only global administrators and promotion administrators can configure load balancing variables. More information is available in the Authorization section.
Along this chapter, you will learn to: