File

mod_prometheus/mod_prometheus.lua @ 4542:fb4a50bf60f1

mod_prometheus: Invoke stats collection if in 'manual' mode Since 10d13e0554f9 a special value for statistics_interval "manual" exists, where a module is expected to invoke processing in connection to collection of stats. This makes internal collection and exporting to Prometheus happens at the same time with no chance of timers getting out of sync.
author Kim Alvefur <zash@zash.se>
date Tue, 13 Apr 2021 23:53:53 +0200
parent 3952:343dc9dd70dd
child 4544:64fa2dd34d43
line wrap: on
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-- Log statistics to Prometheus
--
-- Copyright (C) 2014 Daurnimator
-- Copyright (C) 2018 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
--
-- This module is MIT/X11 licensed.

module:set_global();

local tostring = tostring;
local t_insert = table.insert;
local t_concat = table.concat;
local socket = require "socket";
local statsman = require "core.statsmanager";
local get_stats = statsman.get_stats;

local function escape(text)
	return text:gsub("\\", "\\\\"):gsub("\"", "\\\""):gsub("\n", "\\n");
end

local function escape_name(name)
	return name:gsub("[^A-Za-z0-9_]", "_"):gsub("^[^A-Za-z_]", "_%1");
end

local function get_timestamp()
	-- Using LuaSocket for that because os.time() only has second precision.
	return math.floor(socket.gettime() * 1000);
end

local function repr_help(metric, docstring)
	docstring = docstring:gsub("\\", "\\\\"):gsub("\n", "\\n");
	return "# HELP "..escape_name(metric).." "..docstring.."\n";
end

-- local allowed_types = { counter = true, gauge = true, histogram = true, summary = true, untyped = true };
-- local allowed_types = { "counter", "gauge", "histogram", "summary", "untyped" };
local function repr_type(metric, type_)
	-- if not allowed_types:contains(type_) then
	-- 	return;
	-- end
	return "# TYPE "..escape_name(metric).." "..type_.."\n";
end

local function repr_label(key, value)
	return key.."=\""..escape(value).."\"";
end

local function repr_labels(labels)
	local values = {}
	for key, value in pairs(labels) do
		t_insert(values, repr_label(escape_name(key), escape(value)));
	end
	if #values == 0 then
		return "";
	end
	return "{"..t_concat(values, ", ").."}";
end

local function repr_sample(metric, labels, value, timestamp)
	return escape_name(metric)..repr_labels(labels).." "..value.." "..timestamp.."\n";
end

local allowed_extras = { min = true, max = true, average = true };
local function insert_extras(data, key, name, timestamp, extra)
	if not extra then
		return false;
	end
	local has_extra = false;
	for extra_name in pairs(allowed_extras) do
		if extra[extra_name] then
			local field = {
				value = extra[extra_name],
				labels = {
					["type"] = name,
					field = extra_name,
				},
				typ = "gauge";
				timestamp = timestamp,
			};
			t_insert(data[key], field);
			has_extra = true;
		end
	end
	return has_extra;
end

local function parse_stats()
	local timestamp = tostring(get_timestamp());
	local data = {};
	local stats, changed_only, extras = get_stats();
	for stat, value in pairs(stats) do
		-- module:log("debug", "changed_stats[%q] = %s", stat, tostring(value));
		local extra = extras[stat];
		local host, sect, name, typ = stat:match("^/([^/]+)/([^/]+)/(.+):(%a+)$");
		if host == nil then
			sect, name, typ = stat:match("^([^.]+)%.(.+):(%a+)$");
		elseif host == "*" then
			host = nil;
		end
		if sect:find("^mod_measure_.") then
			sect = sect:sub(13);
		elseif sect:find("^mod_statistics_.") then
			sect = sect:sub(16);
		end

		local key = escape_name("prosody_"..sect);
		local field = {
			value = value,
			labels = { ["type"] = name},
			-- TODO: Use the other types where it makes sense.
			typ = (typ == "rate" and "counter" or "gauge"),
			timestamp = timestamp,
		};
		if host then
			field.labels.host = host;
		end
		if data[key] == nil then
			data[key] = {};
		end
		if not insert_extras(data, key, name, timestamp, extra) then
			t_insert(data[key], field);
		end
	end
	return data;
end

local function get_metrics(event)
	local response = event.response;
	response.headers.content_type = "text/plain; version=0.0.4";
	if statsman.collect then
		statsman.collect()
	end

	local answer = {};
	for key, fields in pairs(parse_stats()) do
		t_insert(answer, repr_help(key, "TODO: add a description here."));
		t_insert(answer, repr_type(key, fields[1].typ));
		for _, field in pairs(fields) do
			t_insert(answer, repr_sample(key, field.labels, field.value, field.timestamp));
		end
	end
	return t_concat(answer, "");
end

function module.add_host(module)
	module:depends "http";
	module:provides("http", {
		default_path = "metrics";
		route = {
			GET = get_metrics;
		};
	});
end