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How to Ack & Reset vCenter Alarm implementing hidden API method

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There was a recent question in the VMTN developers forum around automating the acknowledgment and resetting of a triggered vCenter alarm using vSphere SDK for Perl. This is actually a trivial task using the vSphere Client, you would first identify the alarm and acknowledge the alarm by right clicking on the alarm and selecting "Acknowledge Alarm". To reset the alarm, you would right click on the alarm and select "Reset Alarm to Green".

To automate this task using the vSphere SDK for Perl which uses the vSphere API, you would perform the same two API operations. Doing a search, you will find a method called AcknowledgeAarm which should does exactly that, but if you try to search for method to reset an alarm, you will notice no such method exists. This was something I was aware of since vSphere 3.5 API, but never understood why it was kept hidden.

UPDATE - The AcknowledgeAlarm API has been made public as of vSphere 7.x and later

Here is a screenshot of the alarmManager in the vSphere MOB and you will notice no methods pertains to resetting an alarm:

You might ask, how is the vSphere Client performing this operation and what API method is it using? Sadly, this operation is one of the many hidden API methods that VMware choose to hide and not public expose for various reasons.

However, there are several ways of identifying some of these hidden vSphere API methods and properties. When you install the vSphere Client on your workstation, there is a catalog directory (e.g. C:\Program Files\VMware\Infrastructure\Virtual Infrastructure Client\4.1\Catalogs\Default)  that is created based on the version of vSphere and within the vim directory, there are these *.vmsg files that contain information regarding the VIM API (Virtual Infrastructure Management API) and searching within these files, you will find some hidden goodies.

Searching the task.vmsg file and within the alarm section, you will see a method name called setAlarmStatus:

alarm.AlarmManager.setAlarmStatus.label = "Set alarm status"
alarm.AlarmManager.setAlarmStatus.summary = "Sets the status of an alarm for an entity"

As you can see, there are other methods with respect to the alarmManager that is documented, but the method above is not documented in the vSphere API reference. We can take this information and further validate by using the vSphere MOB to see what parameters are required for this method.

By generating the proper URL, you can see the method is exposed and the required parameters to this function:

We can perform one additional confirmation to ensure that the method above is actually the method the vSphere Client is performing when resetting an alarm. The tool that we will use here is Onyx, yep, it is not only useful for PowerCLI but for all vSphere developers and administrators. I created a dummy alarm that would trigger if a VM is powered on or powered off and by running Onyx to capture the API calls when acknowledging and resetting an alarm.

Here is the output from Onyx:

As you can see, the two operations uses the AcknowledgeAlarm and the hidden SetAlarmStatus API method. We now can definitively say that the above hidden API method is being used and now we need to figure out how we can incorporate this method into the existing vSphere SDK for Perl.

In this example, I will be working with the vSphere SDK for Perl found on vMA 4.1, but the same set of changes will apply to vCLI 4.x being installed on a Windows or Linux system. There are two client Perl stubs or Perl Modules that contains prototype and definition of a vSphere API method:

/usr/lib/perl5/5.8.8/VMware/VIM25Stub.pm (prototype definition)
/usr/lib/perl5/5.8.8/VMware/VIM25Runtime.pm (method definition)

We will first edit the VIM25Runtime.pm module and if you are on vMA, you will need to use 'sudo' to edit the file. We will add the SetAlarmStatus entry try similar the AcknowledgeAlarm method:

Next we will edit the VIM25Stub.pm and again it will be very similar to an existing method, but now we must populate the parameters based on what we discovered from the vSphere MOB:

Now we are ready to implement this method in a vSphere SDK for Perl Script. I quickly threw together a script that helps manages your vCenter alarms using the CLI by listing all active and triggered alarms in either a red or yellow state.

Download Script: alarmManagement.pl

Here is an example of listing all triggered alarms that are either in a red or yellow state:

Here is an example of acking and resetting the above alarm and utilizing the new hidden API method that was just implemented:

There you have it, a method that was once hidden is no longer =)

If you are interested in locating other hidden API goodies, take a look at this post on How to browse the internal vSphere APIs

What's new in the vSphere 4.1 MOB

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The vSphere MOB (Managed Object Browser) is not a well known tool and unless you are a developer, you probably do not know of its existence. The simplest way to describe the vSphere MOB is that it is a debugging tool to graphical visualize all entities within the vSphere API through a web browser. It is often used to better understand the vSphere API/inventory and aide in developing your own vSphere application or script. For a detailed deep dive of the vSphere inventory, check out Steve Jin's post here.

The vSphere MOB can be reached by pointing your web browser to either an ESX(i) or vCenter host followed by the path "/mob". You will be prompted for credentials as you normally would prior to gaining access to the MOB.

The vSphere MOB may not always be the easiest to navigate. Understanding the vSphere inventory structure is definitely helpful, otherwise it can be very confusing to users. With the release of vSphere 4.1, there are two major changes in the MOB that can help make the navigation easier for developers.

Previous to vSphere 4.1, the MOB would display managed entities using their Managed Object IDs (MoRef ID) as a way to uniquely identify these objects. This made it very difficult for developers to identify the specific object you are viewing without having to dig further.

In vSphere 4.1, the MOB provides both the MoRef ID and the translated the names of the managed entities.

The vSphere MOB not only displays information about the managed entities but also provides a way to interact with the system. It does this by listing the available API methods for each managed entity at the bottom of the page and can be executed by providing the correct input parameters. The issue arises when trying to execute methods which requires complex input that require more than a simple string or integer value. The format of the input is XML-based and it can be challenging to generate the correct format, especially without any examples.

In the new version of the MOB, you are now presented with an XML template of the required parameters which can then be filled out to execute the method.

The following example will demonstrate the change of an ESXi advanced configuration value for configuring a syslog server:

Once you have filled in the required parameters, you will need to click on the "Invoke Method" to execute the specific method.

Here we verify the advanced configuration key "Syslog.Remote.Hostname" has been changed and is set to our new syslog server.

I think these two changes will make it easier for developers to navigate the vSphere MOB and assist with understanding the vSphere API and it's managed entities.

Script - Configure VM Disk Shares (vmDiskSharesMgmt.pl)

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I recently received an email about automating the configuration of VM disk shares. I thought it was an interesting request since I do not know how many people actually make use of this feature. By default, the shares on a virtual disk is set to "normal" or 1000 shares. You can change the value between low (500), normal (1000), high (2000) or a custom value. The following script helps a user to perform a bulk update across multiple VMs and supports multiple virtual disks.

Download: vmDiskSharesMgmt.pl

The script requires that you connect to your vCenter server and provide the following input parameters:

--diskshares_file = Is the name of the diskshares input file that contains the names of the VMs, the hard disks and their corresponding shares value which can be (low, normal, high or custom)

Here is an example of the diskshares input file:

[vi-admin@scofield ~]$ cat diskshares.txt
# [VMNAME];[HDX,SHARES_VALUE]=[HDY,SHARES_VALUE]=[HDZ,SHARES_VALUES]
#
# SHARES_VALUE = low, normal, high, XXXX (custom)
#
# e.g.
# myvm;hd1,low=hd2,high=hd3=2001
#
Synapse;hd1,high
Imager;hd1,low=hd2,1500=hd3,2500=hd4,high
William-XP;hd1,3000

In the above example, we have the following VMs and configurations to be set:

Synapse
Hard Disk1 = high (2000)

Imager
Hard Disk1 = low (500)
Hard Disk2 = 1500
Hard Disk3 = 2500
Hard Disk4 = high (2000)

William-XP
Hard Disk1 = 3000

Here is an example execution:

Here we verify one of the VMs "Imager" and it's configured disk shares:

Hopefully you will find this script to be useful