Calculated value for CMDB for rack units occupied.

[Piemur1]

Hello, I wanted to set up an automatic calculation for how many rack units are occupying a rack. I've created a field entry for the devices with the expectation that they will have a value for how many rack units they will occupy (such as servers and any other devices that could be installed within a rack such as switches, routers, PSUs, etc). And then the plan would be for using the CI Relationship "contains::contained by" to pull the items within the rack and then sum up the rack units and display for the "Rack units in use" field on a given Rack. Currently I have the field on the Servers table (cmdb_ci_servers) and planning on adding the field to more later as we identify what items will be tracked in the Racks. I presume I will be using the Script type rather than Formula.

[HIROSHI SATOH]

Understanding the Problem:

You're trying to automatically calculate the total rack units occupied by devices within a rack. You have a field on the cmdb_ci_servers table to capture the rack units occupied by servers. You plan to extend this to other device types and use CI Relationships to sum the values.

Proposed Solution:

• Create a Custom Calculated Field:

  • On the cmdb_ci_rack table, create a calculated field named rack_units_in_use.
  • Set the data type to integer.
  • Select "Script" as the calculation type.

• Write the Script:

// Initialize the sum
var totalRackUnits = 0;

// Get the list of CIs contained by the rack
var grContainment = new GlideRecord('cmdb_rel_ci');
grContainment.addQuery('parent', current.sys_id);  // Assuming current is the Rack CI
grContainment.addQuery('type.name', 'contains::contained by');
grContainment.query();

while (grContainment.next()) {
    var childCI = new GlideRecord(grContainment.child.cmdb_ci);
    if (childCI.get(grContainment.child.sys_id)) {
        totalRackUnits += parseInt(childCI.u_rack_units || 0);  // Assuming u_rack_units is the field name
    }
}

// Update the rack's "Rack units in use" field
current.u_rack_units_in_use = totalRackUnits;

• Explanation:

  • The script queries the cmdb_ci_rack_device table for devices contained within the current rack.
  • It iterates through each device, retrieves the corresponding cmdb_ci_server record, and adds the rack_units value to the total.
  • Finally, it sets the calculated field rack_units_in_use on the current rack record.

Additional Considerations:

• Device Types: Ensure that the script handles other device types besides servers by adjusting the device.get(gr.device) line.
• Performance: For large numbers of devices, consider optimizing the query and calculations to improve performance.
• Data Integrity: Implement validation rules to ensure that rack_units values are valid integers.

[Piemur1]

I think this is the solution, however I'm having trouble getting a result from it. Is the following line supposed to be a new gliderecord for cmdb_ci?

var childCI = new GlideRecord(grContainment.child.cmdb_ci);

Any test records I have that contains a server that has a u_rack_unit value, it returns with a null value, not even an Int. It might even give a null value for servers that DON'T have a u_rack_unit value, haven't had an opportunity to test that yet...But it seems like it is getting stuck in the while loop, and doesn't exit, therefore it never returns a proper value.

[Piemur1]

I have determined that the error occurs somewhere within this if statement:

if (childCI.get(grContainment.child.sys_id)) 

It never reaches within the if statement.

[Piemur1]

Performed some troubleshooting with @HIROSHI SATOH and came up with the following as the final solution:

// Initialize the sum

    var totalRackUnits = 0;

    // Get the list of CIs contained by the rack

    var grContainment = new GlideRecord('cmdb_rel_ci');

    grContainment.addQuery('parent', current.sys_id); // Assuming current is the Rack CI

    grContainment.addQuery('type.name', 'contains::contained by');

    grContainment.query();

    while (grContainment.next()) {

        if (grContainment.child) { // Directly check if the child CI exists

            totalRackUnits += parseInt(grContainment.child.u_rack_units || 0); // Access the rack units field from child CI

        }

    }

    // Update the rack's "Rack units in use" field

    current.u_rack_units_in_use = totalRackUnits;

Again much appreciation for Mr. Satoh for the assistance!