Tag: Discovery

Limitless possibilities – very little code

One of the biggest pet peeves that I’ve had with SCOM discovery is that it was always very agent biased.  If you wanted to discover IIS, for example, the agent would look for the bits and pieces of IIS installed on a server.  While that works fine for most classes and objects, it does pose some limitations.  What if I wanted to add additional properties to an existing object, or mark a server with a custom attribute?  A common work around was to ‘tattoo’ a system with a reg key or perhaps a file, and then discover that via the normal mechanism.  That seems like extra steps for something that should be relatively easy.  I want to run discovery on something other than the agent, and have that discovery data roll up to the agent.

Why would someone want to perform discovery ‘remotely’?  Well, maybe you have a CMDB or an application to server relationship database.  Would you rather put a regkey on every server with the application information, or just query the database?  Imagine being able to have application owner properties (email, phone, manager, etc…) in SCOM as a property for every server, but without having to touch the server at all – no more regkeys or property files.

Microsoft.EnterpriseManagement.ConnectorFramework.IncrementalDiscoveryData

This class – IncrementalDiscoveryData – is an amazingly powerful tool.  The idea is that you can submit additional discovery data for an existing object, or even create brand new objects like normal.  The best way to imagine this is to look at the code itself:

$data = (invoke-sql @DBParams -method query -statement "select * from SomeDataTable").tables.rows 
New-SCOMManagementGroupConnection -ComputerName “localhost”
$mg = Get-SCOMManagementGroup

foreach ($row in $data){
    $class = get-scomclass -displayname $row.ClassName
    $ClassObject=New-Object Microsoft.EnterpriseManagement.Common.CreatableEnterpriseManagementObject($mg,$class)
    $servername = $row.servername
    $ClassObject[$Class.FindHostClass(),“PrincipalName”].Value = "$servername"
    $ClassInstanceDisplayName=$Servername
    $ClassObject[$Class,“AppID”].Value = $row.AppID
    $ClassObject[$Class,“MonitorCI”].Value = $row.MonitorCI
    $discovery=New-Object Microsoft.EnterpriseManagement.ConnectorFramework.IncrementalDiscoveryData
    $discovery.Add($ClassObject)
    $discovery.Overwrite($mg)
}

The first 3 lines are pretty straight forward.  A simple function that querys a database (invoke-sql), creating a connection the the local management server, and getting the management group.

Then we go row by row with what’s in the table.  In this case the table looks something like this:

ClassName	ServerName	AppID	MonitorCI
Microsoft.Windows.Computer	server01	COTS1	AssignmentGroup1
Microsoft.Windows.Computer	server02	Custom2	AssignmentGroup2

The code is going to get the class (in this case $row.classname, which is Microsoft.Windows.Computer), then create a new instance of that class (even if the object exists – we won’t overwrite anything not in the discovery data).  We find the host using the servername , add a couple of our new attributes – AppID and MonitorCI – and then create our discovery object.  That is where the magic happens – 

$discovery=New-Object Microsoft.EnterpriseManagement.ConnectorFramework.IncrementalDiscoveryData

This is the bit that creates the actual discovery object.  Since it’s incremental, we aren’t going to mess with anything already in that object, just update the bits that we add to the discovery object.  In this case, we are adding the $ClassObject that we populated with our additional bits of data – AppID and MonitorCI.    Two more lines, and we have our remotely discovered data as properties in our server object.

    $discovery.Add($ClassObject)
    $discovery.Overwrite($mg)

With just that little bit of code we are able to store attributes, properties, configurations, or anything else in a central database and have a simple PowerShell script that updates the objects in SCOM with that discovery data!  Not only that, those items are not rolled up to some random object, we can roll them up to the exact object we want.  No more regkey tattoos, or configuration files that you have to keep update to date on servers.