contrib/statusd/statusd_exec.lua

   1 -- Authors: Antti Vähäkotamäki
   2 -- License: LGPL, version 2.1 or later
   3 -- Last Changed: 2006
   4 --
   5 -- statusd_exec.lua
   6 --
   7 --
   8 -- -- What is this?
   9 --
  10 -- This is a simple "general" statusd Lua script which
  11 -- lets you show output of external programs in ion
  12 -- statusbar. This is convenient if you are not familiar
  13 -- with Lua but can handle yourself with some other
  14 -- language enough to output what you would want the
  15 -- statusbar to show.
  16 --
  17 -- After this script is loaded it starts executing all
  18 -- the provided programs (wether a placeholder exists in
  19 -- template or not) and updates the statusbar every time
  20 -- one of them prints (and flushes) a line.
  21 --
  22 -- -- How to use it?
  23 --
  24 -- 1 ) update statusbar template to include %exec_something
  25 -- 2 ) specify parameters in cfg_statusbar.lua like this:
  26 --
  27 -- mod_statusbar.launch_statusd{
  28 --
  29 --     [ ... some other config here ... ],
  30 --
  31 --     exec = {
  32 --
  33 --         -- show date each second in %exec_date with.. date!
  34 --
  35 --         date = {
  36 --             program = 'date',
  37 --             retry_delay = 1 * 1000,
  38 --         },
  39 --
  40 --         -- show percentage of hda1 every 30 seconds in
  41 --         -- %exec_hda1u with df, grep and sed.
  42 --         -- also highlights entry if usage is high.
  43 --
  44 --         hda1u = {
  45 --             program = 'df|grep hda1|sed "s/.*\\(..%\\).*/\\1/"',
  46 --             retry_delay = 30 * 1000,
  47 --             meter_length = 4,
  48 --             hint_regexp = {
  49 --                 important = '9[456].',
  50 --                 critical = {
  51 --                     '9[789].',
  52 --                     '1...',
  53 --                 },
  54 --             },
  55 --         },
  56 --
  57 --         -- keep continous track of a remote machine in
  58 --         -- %exec_remote with ssh, bash and uptime.
  59 --         -- if the connection breaks, wait 60 seconds and retry
  60 --
  61 --         remote = {
  62 --             program = 'ssh -tt myhost.com "while (uptime);' ..
  63 --                       'do sleep 1; done"',
  64 --             retry_delay = 60 * 1000,
  65 --         },
  66 --     }
  67 -- }
  68 --
  69 -- -- Description of variables:
  70 --
  71 -- * program
  72 --  The program to execute. The last line of each
  73 --  flushed output this program writes to stdout is
  74 --  inserted as the content of the meter.
  75 --
  76 -- * retry_delay (optional)
  77 --  The delay to wait (ms) before running the program again
  78 --  once it stops sending data. Some programs just
  79 --  send the data and exit while others continue
  80 --  sending data periodically. This value can be used
  81 --  to control the update rate for the first type of
  82 --  programs. You can also specify a value for the other
  83 --  type of programs to retry if the program stops for
  84 --  some reason.
  85 --
  86 -- * meter_length (optional)
  87 --  The space reserved for this meter in characters.
  88 --  If the value is not specified or is less than 1
  89 --  then the space is determined by the length of the
  90 --  data being shown but some people do not want their
  91 --  statusbar width to change randomly.
  92 --
  93 -- * hint_regexp (optional)
  94 --  These regular expressions (in Lua syntax) are
  95 --  matched with the data and in case of a match the
  96 --  named hint is set to the meter. The value can be
  97 --  either a string containing the regexp or a table
  98 --  containing several possible regexps (Lua regexp
  99 --  doesn't have an 'or'). By default the themes define
 100 --  a color for 'important' and 'critical' hints.
 101 --
 102 --
 103
 104 local settings = table.join( statusd.get_config("exec"), {} )
 105 local start_execution = nil
 106 local timers = {}
 107
 108 -- Function for starting and restarting execution of a process
 109
 110 start_execution = function ( key )
 111
 112     -- Set up a function for receiving the data
 113     -- and informing the statusbar
 114
 115     local process_input = function ( new_data )
 116
 117         local received_data = ""
 118
 119         -- When we get new data, output the last complete line
 120
 121         while new_data do
 122             received_data = received_data .. new_data
 123
 124             -- Erase old data which we do not need anymore
 125
 126             received_data = string.gsub( received_data,
 127                                          ".*\n(.*\n.*)", "%1" )
 128
 129             -- Set the last complete line as the current line
 130
 131             local current_line = string.gsub( received_data,
 132                                               "(.*)\n.*", "%1" )
 133
 134             local t_key = "exec_" .. key
 135             local t_length = settings[key].meter_length
 136             local h_regexp = settings[key].hint_regexp
 137
 138             if not tlength or t_length < 1 then
 139                 t_length = string.len( current_line )
 140             end
 141
 142             statusd.inform( t_key .. "_hint", '' )
 143             statusd.inform( t_key .. "_template",
 144                             string.rep( 'x', t_length ) )
 145             statusd.inform( t_key, current_line )
 146
 147             if not h_regexp then h_regexp = {} end
 148
 149             for hint, re in pairs( h_regexp ) do
 150                 if ( type( re ) == 'string' ) then
 151                     re = { re }
 152                 end
 153
 154                 for _, r in ipairs( re ) do
 155                     if ( string.find( current_line, r ) ) then
 156                        statusd.inform(t_key .. "_hint", hint)
 157                     end
 158                 end
 159             end
 160
 161             -- Wait for bgread to signal that more data
 162             -- is available or the program has exited
 163
 164             new_data = coroutine.yield()
 165         end
 166
 167         -- Program has exited.
 168         -- Start a timer for a new execution if set.
 169
 170         if settings[key].retry_delay then
 171             timers[key]:set( settings[key].retry_delay,
 172                              function()
 173                                  start_execution(key)
 174                              end )
 175         end
 176     end
 177
 178     -- Set up a simple function for printing errors
 179
 180     local process_error = function( new_data )
 181         while new_data do
 182             io.stderr:write( "ion-statusd [statusd_exec, key='"
 183                 .. key .. "']: " .. new_data )
 184             io.stderr:flush()
 185             new_data = coroutine.yield()
 186         end
 187     end
 188
 189     -- Execute the program in the background and create
 190     -- coroutine functions to handle input and error data
 191
 192     statusd.popen_bgread( settings[key].program,
 193                           coroutine.wrap( process_input ),
 194                           coroutine.wrap( process_error ) )
 195
 196 end
 197
 198 -- Now start execution of all defined processes
 199
 200 for key in pairs(settings) do
 201     timers[key] = statusd.create_timer()
 202     start_execution(key)
 203 end
 204
 205 --
 206 -- Copyright (c) Antti Vähäkotamäki 2006.
 207 --
 208 -- Ion is free software; you can redistribute it and/or modify it under
 209 -- the terms of the GNU Lesser General Public License as published by
 210 -- the Free Software Foundation; either version 2.1 of the License, or
 211 -- (at your option) any later version.
 212 --