The telemetry provider component enables any node to report its operational attributes via a simple HTTP-based hierarchical key-value format. Provider is modular, easily extendable, and is split into multiple OpenWRT packages as follows:

  • nodewatcher-core provides the basic framework for developing telemetry modules, it is required by all other packages.
  • nodewatcher-clients provides client-related monitoring (in combination with nodogsplash and olsr-mod-actions plugin).
  • nodewatcher-watchdog is responsible for performing periodic testing of node’s network sanity and for attempting to recover from weird situations.
  • nodewatcher-solar provides power regulator telemetry via the solar package.
  • nodewatcher-digitemp provides 1-wire thermometer telemetry via the digitemp package.


Installing these packages should be just a matter of adding our repository to /etc/opkg.conf:

src/gz wlansi

where PLATFORM is one of the supported platforms (currently atheros, brcm24 and ar71xx). Then installing packages should be just a matter of an opkg install.

Source Code

The source code for OpenWRT packages providing telemetry are available on GitHub. Feel free to make pull requests with additional providers you might need, and especially to request improvements to the framework provided in core package for easier and modular development of such providers.

Telemetry Provider for Servers

Servers often do not run OpenWRT, so a Python-based CGI script is available which provides similar telemetry in a compatible format.


Remote invocation scripts are installed into /www/cgi-bin and should be accessible via HTTP URL in the form of http://x.y.z.w/cgi-bin/nodewatcher (where x.y.z.w is the node’s primary IP address).

Individual telemetry modules are installed into /etc/nodewatcher.d/, there is also an example module available in our repository (note that this module is not installed).


The format used by our provider is a simple text format. Lines starting with a semicolon (;) are comments and should be ignored by parsers. Any non-comment line is composed of two parts separated by the first left-wise colon (:). Left part is denoted as key and the right part as value.

All keys form a hierarchy. Namespace atoms are ASCII strings that match the regular expressions based on their position in the hierarchy:

  • Top-level namespace atoms must match [A-Za-z-]+. In addition, if a top-level namespace atom contains a capital letter from the range A-Z, the whole atom must be capitalized. Capitalized top-level atoms are reserved for internal use.
  • Namespace atoms on lower levels must match [a-z0-9-]+.

Each key may contain multiple namespace atoms separated by dots (.), for example a valid key is wireless.radios.ath0.bssid. The format of value is currently not defined and should be considered of a per-key type defined by the module that outputs it. Value must not contain a newline, as newlines separate key-value pairs.

Currently the only special namespace is META. It contains information about installed modules and their versions. This information is available in META.modules.*.serial and is of integer type. Dots in module names are replaced with dashes (-) when they are used as namespace atoms.

In the future this hierarchical namespace will be centrally allocated to individual nodewatcher telemetry providers, but currently the allocations are ad-hoc and may change.


The following is an example of nodewatcher output from one of the nodes:

; nodewatcher monitoring system
META.version: 2
META.modules.core-clients.serial: 1
iptables.redirection_problem: 0
net.losses: 0
META.modules.core-general.serial: 1
general.uuid: 7061c9ab-2bcc-442e-b0bc-d9959b519e75
general.version: hg
general.local_time: 43987
general.uptime: 43987.78 41507.07
general.loadavg: 0.25 0.27 0.30 1/39 523
general.memfree: 14056
general.buffers: 1496
general.cached: 5044
META.modules.core-traffic.serial: 1
iface.eth0.down: 0
iface.eth0.up: 0
iface.eth1.down: 0
iface.eth1.up: 0
iface.wlan0.down: 73108492
iface.wlan0.up: 23656806
iface.edge0.down: 0
iface.edge0.up: 1909300
META.modules.core-vpn.serial: 1
META.modules.core-wireless.serial: 1
wireless.radios.wlan0.bssid: 02:CA:FF:EE:BA:BE
wireless.radios.wlan0.frequency: 2.447
wireless.radios.wlan0.mac: 54:E6:FC:F3:7F:54
wireless.radios.wlan0.rts: off
wireless.radios.wlan0.frag: off
wireless.radios.wlan0.signal: 0
wireless.radios.wlan0.noise: 0
wireless.errors: 0
wifi.bssid: 02:CA:FF:EE:BA:BE
wifi.frequency: 2.447
wifi.mac: 54:E6:FC:F3:7F:54
wifi.rts: off
wifi.frag: off
wifi.signal: 0
wifi.noise: 0
wifi.errors: 0