Thanks to everyone that replied.
Haven't decided which way to go yet, but thanks for all the good info!
Just to clarify a bit, I'm not putting the Pis under any kind of heavy load. They will be running in environmentally "unfriendly" areas (garage, patio, etc), so I want to ensure that they are not overheating, especially in summer (I already have them in custom cooled cases).

thanks!
Peter


On 10/30/2021 6:18 PM, Matt Graham via PLUG-discuss wrote:
> On 2021-10-29 17:57, AZ Pete via PLUG-discuss wrote:
>> 3 Raspberry Pis, 1 Ubuntu, 1 Linux Mint, and am looking for a way that I
>> can monitor them remotely.
>
> You probably don't need to do this unless they're under much heavier load than is usual for home machines.
>
>> a unified dashboard that would list for each server:
>> CPU utilization history, Drive space consumed, Temperature monitoring
>> (CPU, chip set, & hard drive temps), Fan speed monitoring, Some kind
>> of alerting mechanism when a given threshold is passed
>
>> I've looked into Webmin, Glances, Nagios, Collectd & Cockpit. Mostly
>> these seemed to be geared more toward remote admin. But the monitoring
>> that was available didn't seem to include the temperature info or the
>> idea of one unified dashboard.
>
> When I was doing this (a long time ago), it was not possible without 2 separate programs.  We used Ganglia to keep records of CPU load, disk space, free RAM, number of database connections (if the machine was a MySQL server), and other stats.  Ganglia's default configuration had a web page that showed various statistics for all the machines that are set up and running the client Ganglia service.
>
> Ganglia does not notify people about things though.  To send mail to people or put a notice on a web page that said, "WARNING: machine foo-1234 has more than 200 active database connections", we used Nagios. The Nagios server can monitor any parameter that is measurable from the Nagios clients, because Nagios monitors are (were?) Perl scripts that run on the clients.  Perl can easily parse the output from `sensors` or `df` or `free` and return "OK", "Warning", or "Error" as you wish.
>
> There used to be a rather useful firefox extension called nagios-checker that would poll a Nagios web page and display useful information in firefox's status bar.  However, they have improved firefox so much that the extension no longer works.
>
> If installing and configuring this stuff sounds like too much work for a tiny number of machines that are probably not under very heavy load, you're right.  It might be a useful learning experience, but its *practical* value is probably not very high.
>