Using the Agent Builder $hostnames Variable

For many applications, specifically network-aware applications, the hostname on which the application listens and services customer requests must be passed to the application on the command line. Therefore, in many cases, hostname is a parameter you must specify for start, stop, and probe commands for the target resource type (on the Configure screen). However, the hostname on which an application listens is cluster specific--it is determined when the resource is run on a cluster and cannot be determined when Agent Builder generates your resource type code.

To solve this problem, Agent Builder provides the $hostnames variable that you can specify on the command line for the start, stop, and probe commands. You specify the $hostnames variable exactly as you would an actual hostname, for example,

/opt/network_aware/echo_server -p port_no -l $hostnames

When a resource of the target resource type is run on a cluster, the LogicalHostname or SharedAddress hostname configured for that resource (in the Network_resources_used resource property of the resource) is substituted for the value of the $hostnames variable.

If you configure the Network_resources_used property with multiple hostnames, the $hostnames variable contains all of them separated by commas.