Example custom Discovery probe and sensor: populate a CI with text file values

This custom Discovery probe helps you if you need to read a text file from a Windows computer and populate a CI in the CMDB with the values from the file.

Before you begin

Role required: admin

About this task

In this example the user wanted to read files created by BGinfo.

Note:

When you have completed the probe and sensor, place the probe in the appropriate Windows classifier at Discovery Definition > CI Classification > Windows.

Procedure

1. Navigate to Discovery Definition > Probes, and then click New.
2. Complete the following fields:
   • Name: Unique and descriptive name for the probe
   • Probe type: Select Probe.
   • Description: Describe the function of this probe.
   • Used by Discovery: Select this check box
   • ECC queue topic: This is name of the probe the MID server is to run. In this example, we use WMIRunner.
   • ECC queue name: In this example, we use the descriptive name WMI: BGInfo files.
3. Right-click in the header bar and select Save from the context menu.
4. Select the Probe Parameters tab in the Probe form, and then click New.
5. Enter WMI_GetFiles.js as the Name of this parameter.
6. Copy the script below into the Script field and edit as needed.
7. Click Submit.

   
   //
    // Use ServiceNow WMIAPI to gather stats
    //
    var CMD_RETRIES = 3;
    var scanner = getScanner();
    if (scanner) {
      var output = "";
      for(var i = 0; i < CMD_RETRIES; i++) {
         output = scanner.winExec("%SystemRoot%\\system32\\cmd.exe /C type \\\"C:\\Information Systems\\BgInfo\\*.txt\\\"");
         if (output)
            break;
      }
      scanner.appendToRoot("output", output);
    }

8. Navigate to Discovery Definition > Sensors, and then click New.
   Complete the following fields:

   • Name: Use the same name as the matching probe. In this example, we use Windows - Get BGInfo files.
   • Reacts to probe: The name of the probe created in the previous procedure: Windows - Get BGInfo files
   • Sensor type: Select the type of sensor to create - in this example Sensor.
   • Description: Describes the function of this sensor.
   • Script: Copy the script below into the Script field and edit as needed.
   • Sensor type: Determines how the answer from the probe is processed - in this example JavaScript.
9. Click Submit.

    
    
   new DiscoverySensor({ data: {}, process: function(result) { 
    
           this.parseOutput(result.output);
           this.update(this.data);
       },
    
    parseOutput: function(output) {
           var currentFile;
           var files = {};
    
    if (output.startsWith("<wmi")) {
               var bgout = new XMLHelper(output).toObject();
               if (!bgout)
                   return;
    
    output = bgout.output;
           }
    
    var lines = output.split(/\n/);
    
    for(var i = 0; i < lines.length; i++) {
               var line = lines[i];
               if (line.startsWith("C:\\Information Systems\\BgInfo\\")) {
                   currentFile = line.substr(30);
                   files[currentFile] = "";
               } else if (currentFile) {
                   var newLine = line.trim();
                   if (newLine)
                       files[currentFile] += (files[currentFile]? "\n"&nbsp;: "") + newLine;
               }
           }
    
    this.data['u_jack_id'] = files['JackID.txt'];
    this.data['warranty_expiration'] = files['Warranty.txt'];
    this.data['po_number'] = files['Ponum.txt'];},
    type: "DiscoverySensor"
    
    });