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check-vmware | check_vmware_host_memory plugin

Table of Contents

Overview

Nagios plugin used to monitor ESXi host memory.

In addition to reporting current host memory usage, this plugin also reports which VMs are on the host (running or not), how much memory each VM is using as a fixed value and as a percentage of the host's total memory.

Thresholds for CRITICAL and WARNING memory usage have usable defaults, but max memory usage is required before this plugin can be used. See the configuration options section for details.

Output

The output for these plugins is designed to provide the one-line summary needed by Nagios for quick identification of a problem while providing longer, more detailed information for display within the web UI, use in email and Teams notifications (atc0005/send2teams).

See the main project README for details.

Performance Data

Background

Initial support has been added for emitting Performance Data / Metrics, but refinement suggestions are welcome.

Consult the list below for the metrics implemented thus far, the original discussion thread and the Add Performance Data / Metrics support project board for an index of the initial implementation work.

Please add to an existing Discussion thread or open a new one with any feedback that you may have. Thanks in advance!

Supported metrics

NOTE: These metrics are based on the visibility of the service account used to login to the target VMware environment. If the service account cannot see a resource, it cannot evaluate the resource.

Metric Unit of Measurement Description
time milliseconds plugin runtime
vms all (visible) virtual machines on the host
vms_powered_on virtual machines powered on
vms_powered_off virtual machines powered off
memory_usage percentage cpu usage
memory_total Hz the total amount of CPU capacity for the host
memory_used Hz the consumed host memory
memory_remaining Hz the remaining host memory

Optional evaluation

Some plugins provide optional support to limit evaluation of VMs to specific Resource Pools (explicitly including or excluding) and power states (on or off). Other plugins support similar filtering options (e.g., Acknowledged state of Triggered Alarms). See the configuration options, examples and contrib sections for more information.

Installation

See the main project README for details.

Configuration options

Threshold calculations

Nagios State Description
OK Ideal state, memory usage for the specified ESXi host system is within bounds.
WARNING Memory usage crossed user-specified threshold for this state.
CRITICAL Memory usage crossed user-specified threshold for this state.

Command-line arguments

  • Use the -h or --help flag to display current usage information.
  • Flags marked as required must be set via CLI flag.
  • Flags not marked as required are for settings where a useful default is already defined, but may be overridden if desired.
Flag Required Default Repeat Possible Description
branding No false No branding Toggles emission of branding details with plugin status details. This output is disabled by default.
h, help No false No h, help Show Help text along with the list of supported flags.
v, version No false No v, version Whether to display application version and then immediately exit application.
ll, log-level No info No disabled, panic, fatal, error, warn, info, debug, trace Log message priority filter. Log messages with a lower level are ignored. Log messages are sent to stderr by default. See Output for more information.
p, port No 443 No positive whole number between 1-65535, inclusive TCP port of the remote ESXi host or vCenter instance. This is usually 443 (HTTPS).
t, timeout No 10 No positive whole number of seconds Timeout value in seconds allowed before a plugin execution attempt is abandoned and an error returned.
s, server Yes No fully-qualified domain name or IP Address The fully-qualified domain name or IP Address of the remote ESXi host or vCenter instance.
u, username Yes No valid username Username with permission to access specified ESXi host or vCenter instance.
pw, password Yes No valid password Password used to login to ESXi host or vCenter instance.
domain No No valid user domain (Optional) domain for user account used to login to ESXi host or vCenter instance. This is needed for user accounts residing in a non-default domain (e.g., SSO specific domain).
trust-cert No false No true, false Whether the certificate should be trusted as-is without validation. WARNING: TLS is susceptible to man-in-the-middle attacks if enabling this option.
dc-name No No valid vSphere datacenter name Specifies the name of a vSphere Datacenter. If not specified, applicable plugins will attempt to use the default datacenter found in the vSphere environment. Not applicable to standalone ESXi hosts.
host-name Yes No valid ESXi host name ESXi host/server name as it is found within the vSphere inventory.
mc, memory-usage-critical No 95 No percentage as positive whole number Specifies the percentage of memory use (as a whole number) when a CRITICAL threshold is reached.
mw, memory-usage-warning No 80 No percentage as positive whole number Specifies the percentage of memory use (as a whole number) when a WARNING threshold is reached.

Configuration file

Not currently supported. This feature may be added later if there is sufficient interest.

Contrib

See the main project README for details.

Examples

CLI invocation

/usr/lib/nagios/plugins/check_vmware_host_memory --username SERVICE_ACCOUNT_NAME --password "SERVICE_ACCOUNT_PASSWORD" --server vc1.example.com --host-name "esx1.example.com" --memory-usage-warning 80 --memory-usage-critical 95 --trust-cert --log-level info

See the configuration options section for all command-line settings supported by this plugin along with descriptions of each. See the contrib section for information regarding example command definitions and Nagios configuration files.

Of note:

  • The host name is specified (via host-name flag) using the exact value shown in the vSphere inventory (e.g., esx1.example.com)
  • Certificate warnings are ignored.
    • not best practice, but many vCenter instances use self-signed certs per various freely available guides
  • Service Check results output is sent to stdout
  • Logging output is enabled at the info level.
    • logging output is sent to stderr by default
    • logging output is intended to be seen when invoking the plugin directly via CLI (often for troubleshooting)
      • see the Output section of the main README for potential conflicts with some monitoring systems

Command definition

# /etc/nagios-plugins/config/vmware-host-memory.cfg

# Look at a specific host and explicitly provide custom WARNING and CRITICAL
# threshold values.
define command{
    command_name    check_vmware_host_memory
    command_line    $USER1$/check_vmware_host_memory --server '$HOSTNAME$' --domain '$ARG1$' --username '$ARG2$' --password '$ARG3$' --memory-usage-warning '$ARG4$' --memory-usage-critical '$ARG5$' --host-name '$ARG6$' --trust-cert  --log-level info
    }

License

See the main project README for details.

References