Published at 2023-06-01T21:10:17+03:00
Gogios is a minimalistic and easy-to-use monitoring tool I programmed in Google Go designed specifically for small-scale self-hosted servers and virtual machines. The primary purpose of Gogios is to monitor my personal server infrastructure for foo.zone, my MTAs, my authoritative DNS servers, my NextCloud, Wallabag and Anki sync server installations, etc.
With compatibility with the Nagios Check API, Gogios offers a simple yet effective solution to monitor a limited number of resources. In theory, Gogios scales to a couple of thousand checks, though. You can clone it from Codeberg here:
=> https://codeberg.org/snonux/gogios
=> Gogios logo
_____________________________ ____________________________
/ \ / \
| _______________________ || ______________________ |
| / \ || / \ |
| | # Alerts with status c| || | # Unhandled alerts: | |
| | hanged: | || | | |
| | | || | CRITICAL: Check Pizza| |
| | OK->CRITICAL: Check Pi| || | : Late delivery | |
| | zza: Late delivery | || | | |
| | | || | WARNING: Check Thirst| |
| | | || | : OutofKombuchaExcept| |
| \_______________________/ || \______________________/ |
| /|\ GOGIOS MONITOR 1 _ || /|\ GOGIOS MONITOR 2 _ |
\_____________________________/ \____________________________/
!_________________________! !________________________!
------------------------------------------------
ASCII art was modified by Paul Buetow
The original can be found at
https://asciiart.website/index.php?art=objects/computersWith experience in monitoring solutions like Nagios, Icinga, Prometheus and OpsGenie, these tools often came with many features that I didn't necessarily need for personal use. Contact groups, host groups, check clustering, and the requirement of operating a DBMS and a WebUI added complexity and bloat to my monitoring setup.
My primary goal was to have a single email address for notifications and a simple mechanism to periodically execute standard Nagios check scripts and notify me of any state changes. I wanted the most minimalistic monitoring solution possible but wasn't satisfied with the available options.
This led me to create Gogios, a lightweight monitoring tool tailored to my specific needs. I chose the Go programming language for this project as it comes, in my opinion, with the best balance of ease to use and performance.
This is an example alert report received via E-Mail. Whereas, [C:2 W:0 U:0 OK:51] means that we've got two alerts in status critical, 0 warnings, 0 unknowns and 51 OKs.
Subject: GOGIOS Report [C:2 W:0 U:0 OK:51] This is the recent Gogios report! # Alerts with status changed: OK->CRITICAL: Check ICMP4 vulcan.buetow.org: Check command timed out OK->CRITICAL: Check ICMP6 vulcan.buetow.org: Check command timed out # Unhandled alerts: CRITICAL: Check ICMP4 vulcan.buetow.org: Check command timed out CRITICAL: Check ICMP6 vulcan.buetow.org: Check command timed out Have a nice day!
This document is primarily written for OpenBSD, but applying the corresponding steps to any Unix-like (e.g. Linux-based) operating system should be easy. On systems other than OpenBSD, you may always have to replace does with the sudo command and replace the /usr/local/bin path with /usr/bin.
To compile and install Gogios on OpenBSD, follow these steps:
git clone https://codeberg.org/snonux/gogios.git cd gogios go build -o gogios cmd/gogios/main.go doas cp gogios /usr/local/bin/gogios doas chmod 755 /usr/local/bin/gogios
You can use cross-compilation if you want to compile Gogios for OpenBSD on a Linux system without installing the Go compiler on OpenBSD. Follow these steps:
export GOOS=openbsd export GOARCH=amd64 go build -o gogios cmd/gogios/main.go
On your OpenBSD system, copy the binary to /usr/local/bin/gogios and set the correct permissions as described in the previous section. All steps described here you could automate with your configuration management system of choice. I use Rexify, the friendly configuration management system, to automate the installation, but that is out of the scope of this document.
It is best to create a dedicated system user and group for Gogios to ensure proper isolation and security. Here are the steps to create the _gogios user and group under OpenBSD:
doas adduser -group _gogios -batch _gogios doas usermod -d /var/run/gogios _gogios doas mkdir -p /var/run/gogios doas chown _gogios:_gogios /var/run/gogios doas chmod 750 /var/run/gogios
Please note that creating a user and group might differ depending on your operating system. For other operating systems, consult their documentation for creating system users and groups.
Gogios relies on external Nagios or Icinga monitoring plugin scripts. On OpenBSD, you can install the monitoring-plugins package with Gogios. The monitoring-plugins package is a collection of monitoring plugins, similar to Nagios plugins, that can be used to monitor various services and resources:
doas pkg_add monitoring-plugins doas pkg_add nrpe # If you want to execute checks remotely via NRPE.
Once the installation is complete, you can find the monitoring plugins in the /usr/local/libexec/nagios directory, which then can be configured to be used in gogios.json.
Gogios requires a local Mail Transfer Agent (MTA) such as Postfix or OpenBSD SMTPD running on the same server where the CRON job (see about the CRON job further below) is executed. The local MTA handles email delivery, allowing Gogios to send email notifications to monitor status changes. Before using Gogios, ensure that you have a properly configured MTA installed and running on your server to facilitate the sending of emails. Once the MTA is set up and functioning correctly, Gogios can leverage it to send email notifications.
You can use the mail command to send an email via the command line on OpenBSD. Here's an example of how to send a test email to ensure that your email server is working correctly:
echo 'This is a test email from OpenBSD.' | mail -s 'Test Email' your-email@example.com
Check the recipient's inbox to confirm the delivery of the test email. If the email is delivered successfully, it indicates that your email server is configured correctly and functioning. Please check your MTA logs in case of issues.
To configure Gogios, create a JSON configuration file (e.g., /etc/gogios.json). Here's an example configuration:
{
"EmailTo": "paul@dev.buetow.org",
"EmailFrom": "gogios@buetow.org",
"CheckTimeoutS": 10,
"CheckConcurrency": 2,
"StateDir": "/var/run/gogios",
"Checks": {
"Check ICMP4 www.foo.zone": {
"Plugin": "/usr/local/libexec/nagios/check_ping",
"Args": [ "-H", "www.foo.zone", "-4", "-w", "50,10%", "-c", "100,15%" ],
"Retries": 3,
"RetryInterval": 10
},
"Check ICMP6 www.foo.zone": {
"Plugin": "/usr/local/libexec/nagios/check_ping",
"Args": [ "-H", "www.foo.zone", "-6", "-w", "50,10%", "-c", "100,15%" ],
"Retries": 3,
"RetryInterval": 10
},
"www.foo.zone HTTP IPv4": {
"Plugin": "/usr/local/libexec/nagios/check_http",
"Args": ["www.foo.zone", "-4"],
"DependsOn": ["Check ICMP4 www.foo.zone"]
},
"www.foo.zone HTTP IPv6": {
"Plugin": "/usr/local/libexec/nagios/check_http",
"Args": ["www.foo.zone", "-6"],
"DependsOn": ["Check ICMP6 www.foo.zone"]
}
"Check NRPE Disk Usage foo.zone": {
"Plugin": "/usr/local/libexec/nagios/check_nrpe",
"Args": ["-H", "foo.zone", "-c", "check_disk", "-p", "5666", "-4"]
}
}
}EmailTo: Specifies the recipient of the email notifications.
EmailFrom: Indicates the sender's email address for email notifications.
CheckTimeoutS: Sets the timeout for checks in seconds.
CheckConcurrency: Determines the number of concurrent checks that can run simultaneously.
StateDir: Specifies the directory where Gogios stores its persistent state in a state.json file.
Checks: Defines a list of checks to be performed, each with a unique name, plugin path, and arguments.
Adjust the configuration file according to your needs, specifying the checks you want Gogios to perform.
If you want to execute checks only when another check succeeded (status OK), use DependsOn. In the example above, the HTTP checks won't run when the hosts aren't pingable. They will show up as UNKNOWN in the report.
For remote checks, use the `check_nrpe` plugin. You also need to have the NRPE server set up correctly on the target host (out of scope for this document). The `state.json` file mentioned above keeps track of the monitoring state and check results between Gogios runs, enabling Gogios only to send email notifications when there are changes in the check status. ## Running Gogios Now it is time to give it a first run. On OpenBSD, do:
doas -u _gogios /usr/local/bin/gogios -cfg /etc/gogios.json
To run Gogios via CRON on OpenBSD as the `gogios` user and check all services once per minute, follow these steps: Type `doas crontab -e -u _gogios` and press Enter to open the crontab file for the `_gogios` user for editing and add the following lines to the crontab file:
0 7 * * * /usr/local/bin/gogios -renotify -cfg /etc/gogios.json
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