2. Configure apcupsd, SSH keys and SMTP

Configure APC config files

• Configure the APC configuration files – the values below may be spread out across the document. Ensure these lines are set correctly. If using nano, use Ctrl+W in nano to find them (or / in vim).

sudo nano /etc/apcupsd/apcupsd.conf

# For a USB-connected UPS
UPSCABLE usb
UPSTYPE usb

# Leave DEVICE blank for USB auto-detection
DEVICE

# Enable the network server so other devices can query the Pi
NETSERVER on
NISIP 0.0.0.0
NISPORT 3551

# It is also good to enable a self test every two weeks
SELFTEST 336

• Change the readiness value from ‘no’ to ‘yes’ to indicate the config file is ready.

sudo sed -i 's/ISCONFIGURED=no/ISCONFIGURED=yes/' /etc/default/apcupsd

• Start the service, ensure the config is accepted and enable it to start upon boot:

sudo systemctl start apcupsd
sudo systemctl status apcupsd
sudo systemctl enable apcupsd

• Here is how it went in my case – you can see that the service is running but it is reporting communication lost every ca. 10 minutes. This is an indication that something is not quite right – without the communication working, the RPi would not know if UPS switched to battery mode and what is the status of the battery.

• In such cases, try rebooting your RPi and/or connecting it to another USB port.
• To verify that communication is working, run apcaccess . Check specifically for:
  • STATUS —> Usually either ONLINE or ONBATT
  • BCHARGE —> typically the % of the battery. Some models have it as BATTCHG – if that is your case, you will need to change that in the following scripts!

Create an SSH key for password-less access to each host

• Let’s create an SSH key and set it up to make each host reachable without needing a password.

# Switch to root
sudo -i
ssh-keygen -t rsa -b 4096
# Give the key a name and a path, such as '/root/.ssh/upsmanage_rsa' .
# This is to recognize it from other keys.

# Copy the public key to the authorized_keys of each host you want to manage.
# Replace your IPs with each host, such as your Proxmox hosts.
ssh-copy-id -i /root/.ssh/upsmanage_rsa.pub [email protected]
ssh-copy-id -i /root/.ssh/upsmanage_rsa.pub [email protected]

• Then test the connection. You should NOT be asked for a password.

# Test the connection
ssh -i /root/.ssh/upsmanage_rsa [email protected] 'hostname'  # Should return 'proxmox1'
ssh -i /root/.ssh/upsmanage_rsa [email protected] 'hostname'  # Should return 'proxmox2'

# Exit root
exit

Configure your SMTP service

• In this case, I’m using mutt – feel free to use whichever you are comfortable with.
• Let’s install it and configure it:

sudo apt install mutt -y

# Configure it (/etc/Muttrc is the global config, ~/.muttrc is for a user-specific config)
sudo nano /etc/Muttrc

# At the end the end of the file, enter your SMTP details - an example is below:

set smtp_url = "smtps://[email protected]:465/"
set smtp_pass = some_password # Use application passwords when using Gmail
set ssl_force_tls = yes
set realname = "RPI Monitoring"
set from = "[email protected]"
set use_from = yes

• Run a test from the terminal:

echo "This is the message body" | mutt -s "subject" -- [email protected]

What do we have so far?

1. We know the status of our battery and can check for it periodically if we script it.
2. We can reach each Proxmox host to remotely shut it down as root.
3. We can send out alerts via email (later we can configure another way with a pull script with UpTime Kuma).

The next thing on the list is to create that script that can then be added as a cron job to run every minute. Let’s dive in!

Go back to course overview: Automate Graceful Shutdown & Wake on LAN for Proxmox with RPi (APC)