Sensu Memory Check Plugin

• Overview
• Files
• Usage examples
• Configuration
  • Sensu Go
    • Asset registration
    • Asset definition
    • Check definition
  • Sensu Core
    • Check definition
• Installation from source
• Additional notes
• Contributing

Overview

This plugin provides native memory instrumentation for monitoring and metrics collection, including memory usage via free and vmstat, including metrics. NOTE: This plugin may have cross-platform issues.

Files

• bin/check-memory.rb
• bin/check-memory.sh
• bin/check-memory-percent.rb
• bin/check-memory-percent.sh
• bin/check-ram.rb
• bin/check-swap-percent.rb
• bin/check-swap.sh
• bin/check-swap.rb
• bin/metrics-memory-percent.rb
• bin/metrics-memory.rb

check-memory
Evaluate free system memory for Linux-based systems.

check-memory-percent
Evaluate the percentage of free system memory for Linux-based systems.

check-ram
Check the percentage of free RAM.

check-swap-percent
Checks swap usage as a percentage of the total swap.

check-swap
Evaluate swap memory usage for Linux-based systems.

metrics-memory-percent
Read memory statistics as a percentage and put them in a form usable by Graphite. Metrics borrowed from HoardD.

metrics-memory-vmstat
Read memory statistics and put them in a form usable by vmstat.

metrics-memory
Read memory statistics and put them in a form usable by Graphite. Metrics borrowed from HoardD.

Usage examples

Help

check-ram.rb

Usage: /opt/sensu/embedded/bin/check-ram.rb (options)
    -c CRIT
    -f, --free                       checks free threshold, defaults to true
    -m, --megabytes                  Unless --megabytes is specified the thresholds are in percentage of memory used as opposed to MB of ram left
    -u, --used                       checks used threshold, defaults to false
    -w WARN

metrics-memory-percent.rb

Usage: /opt/sensu/embedded/bin/metrics-memory-percent.rb (options)
    -s, --scheme SCHEME              Metric naming scheme, text to prepend to metric

Configuration

Sensu Go

Asset registration

Assets are the best way to make use of this plugin. If you're not using an asset, please consider doing so! If you're using sensuctl 5.13 or later, you can use the following command to add the asset:

sensuctl asset add sensu-plugins/sensu-plugins-memory-checks

If you're using an earlier version of sensuctl, you can download the asset definition from this project's Bonsai Asset Index page.

Asset definition

---
type: Asset
api_version: core/v2
metadata:
  name: sensu-plugins-memory-checks
spec:
  url: https://assets.bonsai.sensu.io/c5391d4ae186484226732344b35cf95c0b07b8ec/sensu-plugins-memory-checks_4.0.0_centos_linux_amd64.tar.gz
  sha512: ea297a85aa3612da7f78d948f9784443fffac511040c5130a2dcde7191a0004044c2ef881e665520cbc64431955ab19920d84de6b5fed85c63da7091c4b93bf0

Check definition

---
type: CheckConfig
spec:
  command: "check-memory.rb"
  handlers: []
  high_flap_threshold: 0
  interval: 10
  low_flap_threshold: 0
  publish: true
  runtime_assets:
  - sensu-plugins/sensu-plugins-memory-checks
  - sensu/sensu-ruby-runtime
  subscriptions:
  - linux

Sensu Core

Check definition

{
  "checks": {
    "metrics-disk-usage": {
      "command": "metric-disk-usage.rb",
      "subscribers": ["linux"],
      "interval": 10,
      "refresh": 10,
      "handlers": ["influxdb"]
    }
  }
}

Installation from source

Sensu Go

See the instructions above for asset registration

Sensu Core

Install and setup plugins on Sensu Core

Additional notes

bin/check-ram.rb

Ruby does not have a good native way to grab information on memory usage (without using C extensions or running shell commands and parsing out). For this reason, check-ram.rb uses a gem called vmstat that has a dependency on a GCC to compile the C extensions.

To avoid errors that occur when trying to compile the C extensions without GCC present, we do not install the vmstat gem by default.

Users who need to use check-ram.rb must install build tools, including GCC. This usually requires two steps but can vary based on your distribution and Ruby setup:

1. Install gcc. If you are on a Debian system, GCC is located in the build-essential package. On RHEL systems, yum groupinstall "Development tools" will provide the required packages.
2. Install the vmstat gem into the path from which Sensu gems are expected to run, sudo /opt/sensu/embedded/bin/gem install vmstat --no-rdoc --no-ri, or the equivalent for installing Sensu gems in your configuration management system.

Certification verification

If you are verifying certificates in the gem install you will need the certificate for the sys-filesystem gem loaded in the gem certificate store.

Contributing

See CONTRIBUTING.md for information about contributing to this plugin.