LUA s6ftrig - Handle S6 Service Events

This library allows to register to one or more S6 service fifodirs. The current status can be retrieved and for state changes can be poll()ed. The queries return a dictionary with the service paths as keys and a string of one or more event characters.

Example

local ftrig = require "s6ftrig"
local posix = require "posix"

local trig = ftrig.init{ "/service/lighttpd", "/service/dropbear2" }

local function printtrig(trig)
  for k,v in pairs(trig) do
    print(string.format("%s: %s", k, v))
  end
end

printtrig(trig:current())
posix.poll({ [trig:fd()] = { events = { IN=true } } }, -1)
printtrig(trig:wait())

s6ftrig API

• state(string) translates the states d D u U s O x to finish, down, up, ready, start, once, exit

• init(array of service dirs) creates an ftrigr object, listening for events on the "/event" fifodirs for all provided service directories.

ftrigr API

• fd() returns the file descriptor to poll() for new events.
• wait() returns new state information or an empty array if there are no new events.
• current returns current service state information by calling s6_svstatus_read() on each service directory..

The sequence:

• t = init()
• t:current()
• posix.poll({ [t:fd()] = { events = { IN=true } } }, -1)
• t:wait()

is race free.