NUT-DRIVER-ENUMERATOR(8)

NAME

nut-driver-enumerator - Tool to map NUT device entries to service instances

SYNOPSIS

nut-driver-enumerator.sh -h

nut-driver-enumerator.sh (no args)

nut-driver-enumerator.sh [--COMMAND]

DESCRIPTION

The nut-driver-enumerator.sh (also known as "NDE") script implements the set-up and querying of the mapping between NUT driver configuration sections for each individual monitored device, and the service instances of an operating system service management framework (on platforms where NUT already supports this integration — currently this covers Linux distributions with systemd and systems derived from Solaris 10 codebase, including proprietary Sun/Oracle Solaris and numerous open-source illumos distributions with SMF), into which such drivers are wrapped for independent execution and management. It may be not installed in packaging for other operating systems.

With each NUT driver represented as a separate service instance, dependencies can be defined (e.g. networked drivers must start after the network ability appears in the OS, but USB/Serial drivers should not wait for that), and they can fail or be brought into maintenance independently (unlike a monolithic service based on upsdrvctl(8) requiring everything configured to be started). For a few special drivers like dummy-ups(8), clone(8), clone-outlet(8), and failover(8) this may also involve a dependency between service instances of different NUT drivers themselves.

This script provides a uniform interface for further NUT tools such as upsdrvsvcctl(8) to implement their logic as platform-independently as was possible and practical. It is not currently intended for end-user consumption (and so is located in the libexec directory), with upsdrvsvcctl exposing the most useful data and actions with its list and resync arguments.

One part of the platform complexity that nut-driver-enumerator.sh hides is the difference of rules for valid service instance names in various frameworks, as well as system tools and naming patterns involved.

Depending on the platform, the script may also be wrapped by different service unit types to run automatically (e.g. upon system start-up, or regularly to pick up changes of ups.conf(5) soon after it is edited, or integrated with a file system monitor to be triggered when the configuration is changed). Some of these modes make sense for use-cases with a rarely (if ever) changing population of power devices, e.g. a home or small-office UPS monitored same way for years at a time; others can help automate a data-center monitoring system where device deployments (or discovery) can be much more dynamic.

COMMANDS

nut-driver-enumerator.sh (no args): Update wrapping of devices into services
nut-driver-enumerator.sh --daemon(=freq): Update wrapping of devices into services in an infinite loop; Default freq is 60 sec.
nut-driver-enumerator.sh --daemon-after(=freq): Update wrapping of devices into services in an infinite loop; first do one run of the loop though, then daemonize (this way service unit is deemed started only when NUT config and driver instances are in sync). Default freq is 60 sec.
nut-driver-enumerator.sh --reconfigure: Stop and un-register all service instances and recreate them (e.g. if new dependency template was defined in a new version of the script or package)
nut-driver-enumerator.sh --get-service-framework: Print the detected service management framework in this OS
nut-driver-enumerator.sh --list-devices: Print list of devices in NUT config
nut-driver-enumerator.sh --list-services: Print list of service instances which wrap registered NUT devices (full name of service unit)
nut-driver-enumerator.sh --list-instances: Print list of service instances which wrap registered NUT devices (just instance suffix)
nut-driver-enumerator.sh --get-service-for-device DEV: Print the full name of service unit which wraps a NUT device named DEV
nut-driver-enumerator.sh --get-device-for-service SVC: Print the NUT device name for full or instance-suffix name of a service unit SVC which wraps it
nut-driver-enumerator.sh --list-services-for-devices: Print a TAB-separated list of service units and corresponding NUT device names which each such unit wraps
nut-driver-enumerator.sh --show-all-configs: Show the complete normalized list of device configuration blocks (same as used later by the parser in the script to make decisions)
nut-driver-enumerator.sh --show-device-config DEV: Show configuration block of the specified NUT device
nut-driver-enumerator.sh --show-device-config-value DEV KEY: Show single configuration key of the specified NUT device

ENVIRONMENT VARIABLES

By default nut-driver-enumerator.sh executed without arguments would automatically start any newly registered service instances wrapping the NUT devices, and would also restart the nut-server service if the configuration was changed. Environment variable AUTO_START=no disables this default part of the action.

Also see below for environment variable REPORT_RESTART_42=no value.

DIAGNOSTICS

nut-driver-enumerator.sh will return a zero exit code if it had nothing to do (all currently defined drivers match all of the currently defined service instances, one-to-one) and if it had no errors in its operation.

Other codes can be returned as a result of re-synchronization of mappings:

42: NUT device sections and system service instances differed before, but now match up — so now the caller should likely restart some services. Note that the drivers' service instances may have been started or stopped as required (by AUTO_START=yes) — but maybe the upsmon or upssched services should restart. If you pass environment variable REPORT_RESTART_42=no then this codepath would return 0 (as a non-error exit code). In default mode, such non-null reconfiguration should cause the nut-driver-enumerator service to restart and this would propagate to other NUT services that depend on it.
13: Sections and services differed, and still do not match up
1: Bad inputs, e.g. unrecognized service management framework
2: Absent or unreadable ups.conf file

AUTHOR

Jim Klimov <jimklimov+nut@gmail.com>