nodewatcher-agent

Nodewatcher agent is a monitoring agent that runs on OpenWrt-supported devices and can provide various telemetry information to the nodewatcher monitor daemon via HTTP.

ubus API

The nodewatcher agent exposes an API via ubus so other applications can access its data feeds. It registers itself under the nodewatcher.agent identifier. Currently the only supported method is get_data which can be used as follows:

$ ubus call nodewatcher.agent get_data
{
  ...
  // Returns data feed in the format described below

The method accepts a single parameter called module which can be used to limit the output to a specific module as follows:

$ ubus call nodewatcher.agent get_data "{ 'module': 'core.general' }"

Monitoring report format

To output monitoring data, JSON format is used as in the following example:

{
  // Each module outputs a section that has the module name as the section key.
  'core.general': {
    // Inside the section a special _meta section is always present, giving
    // some metadata about the module. Currently, the only metadata is the
    // module's version number.
    '_meta': {
      'version': 4
    },
    // Additional sections are module-dependent and contain monitoring data.
    'uuid': '64840ad9-aac1-4494-b4d1-9de5d8cbedd9',
    'hostname': 'test-4',
    'version': 'git.12f427d',
    'kernel': '3.10.36',
    'local_time': 1401093621,
    'uptime': 4612,
    'hardware': {
      'board': 'tl-wr741nd-v4',
      'model': 'TP-Link TL-WR740N/ND v4'
    }
  }
}

All float values are encoded as strings due to the fact that ubus message blobs do not currently support serialization of float/double types.

Modules

The agent is fully modular, with all reporting functionality being implemented in modules which are loaded as shared library plugins. On startup modules are automatically discovered from /usr/lib/nodewatcher-agent. Currently the following modules are implemented:

• core.general provides general information about the running system such as the node's uuid, hostname, kernel and firmware versions, etc.
• core.resources provides system resource usage information such as the amount of memory used, the number and type of running processes, load averages, CPU usage and number of tracker connections.
• core.interfaces reports status and statistics for network interfaces configured via UCI.
• core.wireless provides additional information for wireless interfaces.
• core.keys.ssh provides information about the node's host SSH keys.
• core.clients provides information about the clients currently connected with the node, obtained from DHCP leases file.