Network UPS Tools client for VMWare ESXi
----------------------------------------
Author : Rene Garcia
Date : 23-07-2025
Release: 2.7.1
Licence: GPLv3
PURPOSE
Provide UPS connectivity to a single vSphere Hypervisor
Will shut down properly the host and VMs with vmware-tools installed
if a NUT server tells that the power supply has gone and the UPS
battery level is critical.
There are two binary versions of this bundle depending on the target
processor.
- x86_64 is for 64-bit x86 intel familly processors.
- aarch64 is for 64-bit ARM familly processors.
Currently only ESXi 8 for ARM has been tested sucessfully with the aarch64
bundle.
INSTALL
The old way, for all ESXi versions from ESXi 5.0
- Enable SSH on the hypervisor.
- Copy via scp this TAR archive to /tmp directory on the hypervisor
- Connect via ssh to the hypervisor and type the followind commands
 cd /tmp
 tar -xzvf NutClient-ESXi-2.8.3-2.7.1.x86_64.tar.gz
 ./upsmon-install.sh
- No need to reboot, upsmon can be started immediatly but you need
 to configure it first
- You can delete tmp files and disable SSH on the hypervisor
The modern way, for ESXi 6 and above
- Enable SSH on the Hypervisor.
- Copy via scp the offline bundle ZIP file to /tmp directory on host
- Connect via ssh to the host and type the following command
 esxcli software vib install -d /tmp/NutClient-ESXi-2.8.3-2.7.1-x86_64-offline_bundle.zip
UPDATE
- Same as install but use ./upsmon-update.sh
- Or use esxcli software vib update -d /tmp/NutClient-ESXi-2.8.3-2.7.1-x86_64-offline_bundle.zip
UNINSTALL
- Same as install but use ./upsmon-remove.sh
- Or use esxcli software vib remove -n upsmon
CONFIGURATION
- Open ESXi UI web interface and log in. In 'navigator', select 'Manage' item in 'Host'
- In 'System' tab select 'Advanced Settings' and you can filter with "UserVars.Nut"
- Configure these parameters to match your needs :
 UserVars.NutUpsName : UPS name on remote NUT server
 (ups_name@server_name), can be a space
 separated list of NUT servers.
 UserVars.NutUser : Username to connect to NUT server.
 If you are using more than one NUT server,
 they all need to accept the same user/password.
 UserVars.NutPassword : User password on NUT server.
 UserVars.NutFinalDelay : Seconds to wait on low battery event
 before shutting down.
 UserVars.NutOnBatteryDelay : Seconds to wait running on battery
 before shutting down. Default is 0 to
 disable this feature and wait for low
 battery event before shutting down.
 UserVars.NutMinSupplies : Number of power supplies needed to keep
 the system running.
 UserVars.NutSendMail : Set to 1 if you want a mail to be sent
 on UPS events. Set to 2 for a more detailled
 mail report with all UPS status. Set to 0 for no mail
 UserVars.NutMailTo : Email address to send mail to on UPS events.
 UserVars.NutSmtpRelay : Optional SMTP relay to send mail.
 keep it empty for no relay (the default)
- If you don't see the UserVars parameters restart hostd service on
 hypervisor only if you have no vmware job running
 /etc/init.d/hostd restart
 You will need to reconnect with the client
- Now you can start and enable NUT client on hypervisor boot
- On ESXi UI web interface select 'Manage' item in 'Host'. The select 'Services' tab.
- Highlight NutClient service, in actions enable 'Start and stop with host' 
- Start the NutClient service once configured.
- Everytime you change a value in the UserVars you MUST restart NUT client service
 to reload the configuration.
WARNING
This module is provided "as is" and is not approved by VMWare, you may
lose VMWare support if you install it. Use it at your own risks.
This module was designed for standalone ESXi servers. You should not use it for
ESXi nodes in an HA cluster, otherwise the virtual machines will be abruptly stopped
by the NUT client in the event of a power outage (no clean shutdown/standby in HA mode).
REVISIONS
Version notation is X.Y.Z where Z is for minor evolutions and bug fixes with no new
features. Y is for new features and X is for major evolutions with possible break of
ascending compatibility.
1.0.0 - 26/05/2012 - internal beta release
1.0.1 - 28/05/2012 - initial release
1.0.2 - 27/06/2012 - nut updated to version 2.6.4
1.1.0 - 23/02/2013 - nut updated to version 2.6.5 - messages to syslog
1.2.0 - 01/09/2013 - finaldelay is configurable - date in emails is RFC-2822 compliant
1.3.0 - 22/10/2014 - nut updated to version 2.7.2 - multi NUT servers support
1.4.0 - 16/04/2016 - nut updated to version 2.7.4 - SSL support with embeded libressl 2.3.0
2.0.0 - 27/01/2017 - compliant with community level on ESXi 6.x
2.0.1 - 23/05/2019 - set security policy for ESXi 6.7 update 2
2.1.0 - 26/05/2019 - libressl 2.9.2 - vib compatible with ISO integration
2.1.1 - 01/06/2020 - libressl 3.1.2 - fixed FROM value on smtp protocol for email notifications
2.1.2 - 11/01/2021 - libressl 3.2.3 - tested on ESXi 7.0
2.1.3 - 22/03/2021 - libressl 3.2.5
2.1.4 - 21/04/2021 - build also an offline depot for image builder, keep nut tools version
2.1.5 - 07/05/2021 - libressl 3.3.3
2.1.6 - 29/08/2021 - libressl 3.3.4
2.1.7 - 29/12/2021 - libressl 3.4.2
2.2.0 - 14/02/2022 - minsupplies is configurable
2.2.1 - 17/02/2022 - typo on parameter description
2.2.2 - 17/02/2022 - naming issue fixed in offline bundle, no changes in code
2.3.0 - 02/05/2022 - nut 2.8.0, libressl 3.5.2
2.3.1 - 23/08/2022 - libressl 2.5.3 - ESXi 8.0 support
2.3.2 - 19/10/2022 - ESXi 8.0 support, 64-bit binaries
2.4.0 - 23/10/2022 - New feature: Configurable shutdown delay when running on battery
2.4.1 - 21/11/2022 - libressl 3.6.1 - Fix on battery delay shutdown with multiple ups setup
2.4.2 - 19/02/2023 - libressl 3.6.2
2.5.0 - 01/11/2023 - nut updated to version 2.8.1 - libressl 3.7.3 - UserVars description
2.6.0 - 17/11/2023 - new SMTP relay feature for mail notifications - verbose mail option
2.6.1 - 05/12/2023 - Fix default SMPT value to 'none' to be supported on ESXi 6.7 and previous
2.6.2 - 04/04/2024 - nut 2.8.2, libressl 3.9.1
2.7.0 - 27/04/2025 - nut 2.8.3, libressl 4.0.0
2.7.1 - 23/07/2025 - libressl 4.1.0 - ESXi for ARM - ESXi 9.0 support