Lua script of server status monitoring for nginx

stat.lua

string.split_it = function(str, sep)
  if str == nil then return nil end
  assert(type(str) == "string", "str must be a string")
  assert(type(sep) == "string", "sep must be a string")
  return string.gmatch(str, "[^\\" .. sep .. "\n]+")
end
string.split = function(str, sep)
  local ret = {}
  for seg in string.split_it(str, sep) do
    ret[#ret+1] = seg
  end
  return ret
end
string.encode = function(str)
  str = string.gsub(str, '\\', '\\\\')
  str = string.gsub(str, '"', '\\"')
  str = string.gsub(str, "'", "\\'")
  str = string.gsub(str, '\n', '\\n')
  str = string.gsub(str, '\t', '\\t')
  return str
end
function jsonEncode(v)
  if v == nil then return 'null' end
  local t = type(v)
  if t == 'string' then
    return '"' .. v:encode() .. '"'
  end
  if t == 'number' then
    return tostring(v)
  end
  if t == 'boolean' then
    return tostring(v)
  end
  if t == 'table' then
    local ret = {}
    for key,val in pairs(v) do
      table.insert(ret, '"' .. key:encode() .. '": ' .. jsonEncode(val))
    end
    return '{' .. table.concat(ret, ',') .. '}'
  end
  return 'null'
end


ret = {}
daemons = {'sshd', 'cron', 'ntpd', 'named', 'snmpd', 'mpd5', 'httpd', 'nginx', 'java', 'squid', 'mysqld', 'postfix', 'dovecot', 'fetchmail', 'sendmail', 'smbd', 'transmission'}

----------------
-- get uptime --
----------------
o = assert(io.popen('/usr/bin/uptime', 'r'))
u = o:read('*a')
o:close()
local _, _, up, user, l1, l2, l3 = u:find("up (.+), (%d+) users?, load averages: ([0-9%.]+),%s([0-9%.]+),%s([0-9%.]*)")

local t = {}
local uptime = 0
_, _, t[1] = up:find("(%d+) days?")
_, _, t[2] = up:find("(%d+) hrs?")
_, _, t[3], t[4] = up:find("(%d+):(%d+)")
_, _, t[5] = up:find("(%d+) mins?")
for k,v in pairs({1440, 60, 60, 1, 1}) do
  uptime = uptime + tonumber((t[k] ~= nil) and t[k] or 0) * v
end

ret['uptime'] = uptime
ret['user']   = tonumber(user)
ret['1min']   = l1
ret['5min']   = l2
ret['10min']  = l3

-----------------------
-- get daemon status --
-----------------------
ds = {}
o = assert(io.popen('/bin/ps auxww'))
p = o:read('*a')
o:close()
for k,v in pairs(daemons) do
  ds[v] = p:find(v)~=nil
end
ret['dstats'] = ds

ngx.print(jsonEncode(ret))