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#!/usr/bin/lua
-- Metrics web server
-- Copyright (c) 2016 Jeff Schornick <jeff@schornick.org>
-- Copyright (c) 2015 Kevin Lyda
-- Licensed under the Apache License, Version 2.0
socket = require("socket")
-- Parsing
function space_split(s)
local elements = {}
for element in s:gmatch("%S+") do
table.insert(elements, element)
end
return elements
end
function get_contents(filename)
local f = io.open(filename, "rb")
local contents = ""
if f then
contents = f:read "*a"
f:close()
end
return contents
end
-- Metric printing
function print_metric(metric, labels, value)
local label_string = ""
if labels then
for label,value in pairs(labels) do
label_string = label_string .. label .. '="' .. value .. '",'
end
label_string = "{" .. string.sub(label_string, 1, -2) .. "}"
end
output(string.format("%s%s %s", metric, label_string, value))
end
function metric(name, mtype, labels, value)
output("# TYPE " .. name .. " " .. mtype)
local outputter = function(labels, value)
print_metric(name, labels, value)
end
if value then
outputter(labels, value)
end
return outputter
end
function timed_scrape(collector)
local start_time = socket.gettime()
local success = 1
local status, err = pcall(collector.scrape)
if not status then
success = 0
print(err)
end
return (socket.gettime() - start_time), success
end
function run_all_collectors(collectors)
local metric_duration = metric("node_scrape_collector_duration_seconds", "gauge")
local metric_success = metric("node_scrape_collector_success", "gauge")
for _,cname in pairs(collectors) do
if col_mods[cname] ~= nil then
local duration, success = timed_scrape(col_mods[cname])
local labels = {collector=cname}
metric_duration(labels, duration)
metric_success(labels, success)
end
end
end
-- Web server-specific functions
function http_ok_header()
output("HTTP/1.0 200 OK\r\nServer: lua-metrics\r\nContent-Type: text/plain; version=0.0.4\r\n\r")
end
function http_not_found()
output("HTTP/1.0 404 Not Found\r\nServer: lua-metrics\r\nContent-Type: text/plain\r\n\r\nERROR: File Not Found.")
end
function serve(request)
local q = request:match("^GET /metrics%??([^ ]*) HTTP/1%.[01]$")
if q == nil then
http_not_found()
else
http_ok_header()
local cols = {}
for c in q:gmatch("collect[^=]*=([^&]+)") do
cols[#cols+1] = c
end
if #cols == 0 then
cols = col_names
end
run_all_collectors(cols)
end
client:close()
return true
end
-- Main program
for k,v in ipairs(arg) do
if (v == "-p") or (v == "--port") then
port = arg[k+1]
end
if (v == "-b") or (v == "--bind") then
bind = arg[k+1]
end
end
col_mods = {}
col_names = {}
ls_fd = io.popen("ls -1 /usr/lib/lua/prometheus-collectors/*.lua")
for c in ls_fd:lines() do
c = c:match("([^/]+)%.lua$")
col_mods[c] = require('prometheus-collectors.'..c)
col_names[#col_names+1] = c
end
ls_fd:close()
if port then
server = assert(socket.bind(bind, port))
while 1 do
client = server:accept()
client:settimeout(60)
local request, err = client:receive()
if not err then
output = function (str) client:send(str.."\n") end
if not serve(request) then
break
end
end
end
else
output = print
run_all_collectors(col_names)
end
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