check_system_basics

check_system_basics is a monitoring plugin, which is capable of retrieving and processing various Linux metrics such as memory or filesystem usage.

In the current version check_system_basics supports the memory, filesystem, psi, sensors, netdev and load sub commands.

Usage

memory

Basic usage:

check_system_basics memory

A sub command to measure and evaluate memory and swap usage. This is not a trivial topic, but there is detailed information available for those who search for it.

For the memory usage thresholds can be applied to either available, free or used memory. The recommended way is to set thresholds for available memory, since this is probably the metric most administrators are interested in.

filesystem

Basic usage:

check_system_basics filesystem

A sub command to check the usage of the currently mounted filesystems.

Thresholds can be applied on absolute values (in bytes) or percentage values of space or inode usage on the filesystem.

• With --exclude-fs-type and --include-fs-type specific filesystem types can be excluded or explicitly included. This matches golang re regular expressions
• With --exclude-device-path and --include-device-path specific device paths can be excluded or explicitly included. This matches golang re regular expressions
• With --exclude-mount-path and --include-mount-path specific mount paths can be excluded or explicitly included. This matches golang re regular expressions

load

Basic usage:

check_system_basics load

A sub command to retrieve the current system load values and alert if these are not within the defined thresholds.

By default no thresholds are applied.

psi

Note: The Pressure stall information interface is not available on all current Linux distributions (specifically it is not activated in their kernel configuration). Therefore this command is not available and will exit with an error.

Basic usage:

check_system_basics psi

A sub command to retrieve the current "pressure stall information" values of the system. These are useful metrics to determine a shortage of resources on the system, the resources being cpu, memory and io. For each of these resources a 10 second, 60 second and 300 second aggregate percentage value is available for which amount of time a process did not immediately receive the resource it was asking for and was therefore stalled.

The PSI interface might not be available on your systems, since not all distributions build it into their kernel or deactivate it (RHEL for example). In this case, the Plugin will return UNKNOWN.

At least on RHEL systems the PSI interface can be enabled via appending "psi=1" to the kernel commandline (/etc/default/grub).

The checks includes the three components CPU, IO and Memory by default, but individual components can be selected with the following flags:

--include-cpu
--include-memory
--include-io

Default thresholds are applied to all of the measurements.

sensors

Basic usage:

check_system_basics sensors

A sub command to read the sensors exposed by the linux kernel and display whether they are within their respective thresholds (if any are set on the system side). Additionally it will export the respective values as performance data to be rendered by a graphing system.

There are no parameters available yet.

Building

Necessary tools

• the golang toolchain

Compiling

go build

executed in the main folder of this repository will generate an executable. If you are not on a linux system, it should probably look like this:

GOOS=linux go build

alternatively there is a Makefile included, so

make

should do the trick.

Creating the Icinga2 CheckCommand config (if necessary)

The plugin can generate the CheckCommand configuration for Icinga2 itself. This might not be perfect in every situation but might be helpful nonetheless.

check_system_basics --dump-icinga2-config > myConfigFile.conf