Monitoring a Raspberry Pi with Telegraf and Aria Operations

I recently set out to configure the open-source Telegraf agent on a physical system in my lab, with the goal of sending telemetry data to Aria Operations. The process for setting this up is documented here: https://techdocs.broadcom.com/us/en/vmware-cis/aria/aria-operations/8-18/vmware-aria-operations-configuration-guide-8-18/connect-to-data-sources/monitoring-applications-and-os-using-open-source-telegraf/monitoring-applications-using-open-source-telegraf/monitoring-applications-using-open-source-telegraf-on-a-linux-platform-saas-onprem.html. Since most of my lab systems are virtualized, the only physical candidate available was a Raspberry Pi running Ubuntu 24.04, and with its ARM-based CPU, I wasn’t sure if it would be supported.

Installing Telegraf on ARM (Ubuntu 24.04)

The first step was to install telegraf from the appropriate repository.

sudo curl -fsSL https://repos.influxdata.com/influxdata-archive_compat.key -o /etc/apt/keyrings/influxdata-archive_compat.key
echo "deb [signed-by=/etc/apt/keyrings/influxdata-archive_compat.key] https://repos.influxdata.com/ubuntu stable main" | sudo tee /etc/apt/sources.list.d/influxdata.list
sudo apt update
sudo apt -y install telegraf

I then needed to download the utility script to help configure telegraf to send to Aria Operations.

wget --no-check-certificate https://cm-opscp-01.lab.enterpriseadmins.org/downloads/salt/telegraf-utils.sh
chmod +x telegraf-utils.sh

The telegraf-utils.sh script requires an auth token. I accessed the Swager UI at https://ops.example.com/suite-api and used the /auth/token/acquire endpoint to generate the token. Here is the body I submitted.

{
  "username" : "svc-physvr",
  "password" : "VMware1!"
}

In this case, the svc-physvr is a user account created in the Aria Operations UI which maps to a limited access user account. The response body included the necessary token value, which I used when invoking the helper script:

sudo ./telegraf-utils.sh opensource -c 192.168.45.73 -t 24c884f0-2558-40fa-9626-61f577487ea5::7d209766-11f2-456a-a2d9-2a40b4459920 -v 192.168.45.73 -d /etc/telegraf/telegraf.d -e /usr/bin/telegraf

The parameters used in this script are explained in the product documentation.

Finally, I restarted the telegraf service.

sudo systemctl restart telegraf

Unfortunately that was met with an error.

Job for telegraf.service failed because the control process exited with error code.
See "systemctl status telegraf.service" and "journalctl -xeu telegraf.service" for details.

Looking at the logs, we could see that a certificate could not be read

sudo journalctl --no-pager -u telegraf

[...]
Jun  12 19:53:09 rpi-extdns-01 telegraf[1292]: 2025-06-12T18:53:09Z E! loading config file /etc/telegraf/telegraf.d/cloudproxy-http.conf failed: error parsing http array, could not load certificate "/etc/telegraf/telegraf.d/cert.pem": open /etc/telegraf/telegraf.d/cert.pem: permission denied
Jun  12 19:53:09 rpi-extdns-01 systemd[1]: telegraf.service: Main process exited, code=exited, status=1/FAILURE
[...]

I checked permissions on the cert.pem file and confirmed it was owned by root for user and group. The same was true for the key.pem file. I adjusted permissions for both files and tried again:

sudo chown telegraf:telegraf /etc/telegraf/telegraf.d/cert.pem
sudo chown telegraf:telegraf /etc/telegraf/telegraf.d/key.pem
sudo systemctl restart telegraf

This time no errors occurred. In short, the Telegraf service was unable to read its TLS certificate files because they were owned by root, but the service runs as the telegraf user. Fixing ownership resolved the issue.

Validating Success in Aria Operations

After waiting some time, I could see data in Aria Operations for this physical server. I first searched for the VM name and found an object called “Linux OS on rpi-extdns-01” (the servers hostname).

Clicking on that object allowed me to view metrics/properties which were collected. For example, the below screenshot shows the disk used over time for the root file system.

More details on this system could be found in the dashboard “Linux OS discovered by Telegraf.”

Conclusion

It’s great to have full visibility into this physical server using the same Aria Operations dashboards and alerts I already rely on for virtual systems. The setup was straightforward, and with a few tweaks for file permissions, the integration worked well even on a low-cost Raspberry Pi with an ARM processor.