Anatomy of a Perl Script
- Uday Dubey (Deactivated)
Note
Well-known variables for Perl and CCS scripting are listed in the topic Scripting Well-Known Variables (Perl, Python, and CCS).
Perl scripts use a script header similar to a CCS script, contained within a well-known comment block. The script header block influences a number of runtime behaviors, including:
Script-Timeout
Specifies the per-command timeout for the entire script in seconds.
- Type: Integer
- Required: No
- Default if not specified: 60
Script-Login
Specifies whether the job engine should automatically establish a connection with the target device.
- Type: Boolean
- Required: No
- Default if not specified: true
Script-Variables
Specifies inputs needed by the script.
- Type: Tuple (ordered list of elements)
- Required: No
- Default if not specified: None
Script-Filter
Specifies the device types processed by the script.
- Type: String
- Required: Yes
A Perl Script header block must be defined inside of Perl comments within a "well known" comment section (between BEGIN-SCRIPT-BLOCK and a # END-SCRIPT-BLOCK). The following example demonstrates the difference between a CCS and Perl Script header block that specifies a Script-Filter that applies to all Cisco IOS devices.
As a comparison, a CCS implementation is straightforward:
Script-Filter:$Vendor == "Cisco" and $sysDesc like /IOS/
You can filter by the network view:
Script-Filter:$network == "blue"
A comparable Perl implementation is as follows:
BEGIN-SCRIPT-BLOCK
Script-Filter:$Vendor == "Cisco" and $sysDesc like /IOS/
END-SCRIPT-BLOCK
Perl scripts run inside the sandbox, using the Perl API to communicate with the Device Interaction Server (DIS) on NetMRI. The DIS proxies CLI requests/responses to/from network devices on behalf of the Perl scripts. Before commands can be sent to a network device, a Perl script must first establish a DIS session (see v2 API object DisSession). After a session has been established, a CLI connection with the target device must be established for the given session (see v2 API object CliConnection). The majority of the time, a Perl script will follow this same initialization sequence. First, establish the API session, establish the DIS session, then establish a CLI connection with the target device. For this reason, Infoblox_Job.pm, a pre-installed Perl library, is provided in the appliance (see Configuration Management > Job Management > Library > Infoblox_Job).