160 lines
4.3 KiB
ReStructuredText
160 lines
4.3 KiB
ReStructuredText
Announcing Node Information
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===========================
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Gluon is capable of announcing information about each node to the mesh
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and to neighbouring nodes. This allows nodes to learn each others hostname,
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IP addresses, location, software versions and various other information.
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Format of collected data
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------------------------
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Information to be announced is currently split into two categories:
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nodeinfo
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In this category (mostly) static information is collected. If
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something is unlikely to change without human intervention it should be
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put here.
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statistics
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This category holds fast changing data, like traffic counters, uptime,
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system load or the selected gateway.
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Both categories will have a ``node_id`` key be default. It should be used to
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match data from *statistics* to *nodeinfo*.
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Accessing Node Information
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--------------------------
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There are two packages responsible for distribution of the information. For
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one, information is distributed across the mesh using alfred_. Information
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between neighbouring nodes is exchanged using `gluon-announced`.
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.. alfred: http://www.open-mesh.org/projects/alfred
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alfred (mesh bound)
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~~~~~~~~~~~~~~~~~~~
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The package ``gluon-alfred`` is required for this to work.
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Using alfred both categories are distributed within the mesh. In order to
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retrieve the data you'll need both a local alfred daemon and alfred-json_
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installed. Please note that at least one alfred daemon is required to run as
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`master`.
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.. alfred-json: https://github.com/tcatm/alfred-json
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`nodeinfo` is distributed as alfred datatype `158`, while `statistics` uses
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`159`. Both are compressed using GZip (alfred-json can handle the decompression).
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In order to retrieve statistics data you could run:
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::
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# alfred-json -z -r 159
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{
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"f8:d1:11:7e:97:dc": {
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"processes": {
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"total": 55,
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"running": 2
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},
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"idletime": 30632.290000000001,
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"uptime": 33200.07,
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"memory": {
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"free": 1660,
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"cached": 8268,
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"total": 29212,
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"buffers": 2236
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},
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"node_id": "f8d1117e97dc",
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"loadavg": 0.01
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},
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"90:f6:52:3e:b9:50": {
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"processes": {
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"total": 58,
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"running": 2
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},
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"idletime": 28047.470000000001,
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"uptime": 33307.849999999999,
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"memory": {
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"free": 2364,
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"cached": 7168,
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"total": 29212,
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"buffers": 1952
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},
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"node_id": "90f6523eb950",
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"loadavg": 0.34000000000000002
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}
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}
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You can find more information about alfred in its README_.
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.. README_: http://www.open-mesh.org/projects/alfred/repository/revisions/master/entry/README
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gluon-announced
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~~~~~~~~~~~~~~~
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`gluon-announced` allows querying neighbouring nodes for their `nodeinfo`.
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It is a daemon listening on the multicast address ``ff02::2:1001`` on
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UDP port 1001 on the bare mesh interfaces. There is no client yet (but it's
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being developed), but you can query the information using tools like ``socat``:
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::
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# socat - UDP6-DATAGRAM:[ff02::2:1001%wlan0-1]:1001
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nodeinfo
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This output is not compressed, but that is likely to change in the future. If
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you intent to use ``gluon-announced``, please contact `tcatm` in Gluon's IRC
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channel.
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Adding a fact
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-------------
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To add a fact just add a file to either ``/lib/gluon/announce/nodeinfo.d/`` or
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``/lib/gluon/announce/statistics.d/``.
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The file must contain a lua script and its name will become the key for the
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resulting JSON object. A simple script adding a ``hostname`` field might look
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like this:
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::
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return uci:get_first('system', 'system', 'hostname')
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The directory structure will be converted to a JSON object, i.e. you may
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create subdirectories. So, if the directories look like this
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::
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.
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├── hardware
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│ └── model
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├── hostname
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├── network
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│ └── mac
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├── node_id
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└── software
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└── firmware
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the resulting JSON would become:
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::
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# /lib/gluon/announce/announce.lua nodeinfo
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{
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"hardware" : {
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"model" : "TP-Link TL-MR3420 v1"
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},
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"hostname" : "mr3420-test",
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"network" : {
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"mac" : "90:f6:52:82:06:02"
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},
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"node_id" : "90f652820602",
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"software" : {
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"firmware" : {
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"base" : "gluon-v2014.2-32-ge831099",
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"release" : "0.4.1+0-exp20140720"
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}
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}
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}
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