view mod_prometheus/mod_prometheus.lua @ 3866:c0df50ce96f0

mod_rest: Handle internal http request errors early and then return Skips over attempted parsing of the payload which usually failed since the body is an error string like "connection refused", so this produced useless errors.
author Kim Alvefur <zash@zash.se>
date Sat, 25 Jan 2020 20:22:12 +0100
parents ccbfe7df02dc
children 343dc9dd70dd
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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();
module:depends "http";

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

	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:provides("http", {
		default_path = "metrics";
		route = {
			GET = get_metrics;
		};
	});
end