Add vCenter Alarm support

[dougm]

vcsim: add AlarmManager
govc: add alarm commands
api: add alarm package with helpers for AlarmManager and Alarms
govc: add event.post command
fix: govc: output Message field for 'EventEx' types

[dilyar85]

I built a govc locally from your change, but when I ran the alarm commands with $vm passed, I always get the following error:

$ govc alarms vm-lcm-izrm
govc: 2 objects at path "vm-lcm-izrm": [VirtualMachine:vm-159 VirtualMachine:vm-159]

I don't think this is specific to your change as the error message seems to be coming from the datacenter.go file here: https://github.com/vmware/govmomi/blob/main/govc/flags/datacenter.go#L177.

Other than that, the change LGTM. Thanks again for adding this support in all components!

[dougm]

Thanks for reviewing and trying it out @dilyar85 !
I pushed an update so the alarms doc mentions to use an inventory path. Also changed the error message a bit:

% govc alarms vm-lcm-oyr0
govc: 2 objects match "vm-lcm-oyr0": [VirtualMachine:vm-174 VirtualMachine:vm-174] (unique inventory path required)

You can see with govc tree -l -p /, each vm shows up under the vm folder and under its host, those are the 2 matches found.

Since you're trying it out, you can see the alarms in action w/ the doc from create:

% export GOVC_SHOW_UNRELEASED=true
% govc alarm.create -n "My Alarm" -green my.alarm.success -yellow my.alarm.failure
% govc event.post -i my.alarm.failure vm/folder/vm-name
% govc alarms vm/folder/vm-name

[dilyar85]

Thanks for reviewing and trying it out @dilyar85 ! I pushed an update so the alarms doc mentions to use an inventory path. Also changed the error message a bit:

% govc alarms vm-lcm-oyr0
govc: 2 objects match "vm-lcm-oyr0": [VirtualMachine:vm-174 VirtualMachine:vm-174] (unique inventory path required)

You can see with govc tree -l -p /, each vm shows up under the vm folder and under its host, those are the 2 matches found.

Since you're trying it out, you can see the alarms in action w/ the doc from create:

% export GOVC_SHOW_UNRELEASED=true
% govc alarm.create -n "My Alarm" -green my.alarm.success -yellow my.alarm.failure
% govc event.post -i my.alarm.failure vm/folder/vm-name
% govc alarms vm/folder/vm-name

Yep, it worked perfectly after specifying the VM inventory path:

$ govc alarm.create -n "My Alarm" -green my.alarm.success -yellow my.alarm.failure
$  govc event.post -i my.alarm.failure vm/Namespaces/vm-lcm-6hgu25/vm-lcm-oyr0
$ govc alarms vm/Namespaces/vm-lcm-6hgu25/vm-lcm-oyr0
Alarm Name  Object                 Severity  Triggered Time   Acknowledged Time  Acknowledged By
My Alarm    VirtualMachine:vm-174  Warning   Aug  9 16:35:49

Thanks for improving the error message as well!

[dilyar85]

LGTM!