Statistics: Rewrite statistics backends to use OpenMetrics The metric subsystem of Prosody has had some shortcomings from the perspective of the current state-of-the-art in metric observability. The OpenMetrics standard [0] is a formalization of the data model (and serialization format) of the well-known and widely-used Prometheus [1] software stack. The previous stats subsystem of Prosody did not map well to that format (see e.g. [2] and [3]); the key reason is that it was trying to do too much math on its own ([2]) while lacking first-class support for "families" of metrics ([3]) and structured metric metadata (despite the `extra` argument to metrics, there was no standard way of representing common things like "tags" or "labels"). Even though OpenMetrics has grown from the Prometheus world of monitoring, it maps well to other popular monitoring stacks such as: - InfluxDB (labels can be mapped to tags and fields as necessary) - Carbon/Graphite (labels can be attached to the metric name with dot-separation) - StatsD (see graphite when assuming that graphite is used as backend, which is the default) The util.statsd module has been ported to use the OpenMetrics model as a proof of concept. An implementation which exposes the util.statistics backend data as Prometheus metrics is ready for publishing in prosody-modules (most likely as mod_openmetrics_prometheus to avoid breaking existing 0.11 deployments). At the same time, the previous measure()-based API had one major advantage: It is really simple and easy to use without requiring lots of knowledge about OpenMetrics or similar concepts. For that reason as well as compatibility with existing code, it is preserved and may even be extended in the future. However, code relying on the `stats-updated` event as well as `get_stats` from `statsmanager` will break because the data model has changed completely; in case of `stats-updated`, the code will simply not run (as the event was renamed in order to avoid conflicts); the `get_stats` function has been removed completely (so it will cause a traceback when it is attempted to be used). Note that the measure_*_event methods have been removed from the module API. I was unable to find any uses or documentation and thus deemed they should not be ported. Re-implementation is possible when necessary. [0]: https://openmetrics.io/ [1]: https://prometheus.io/ [2]: #959 [3]: #960

-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local usermanager = require "core.usermanager";
local new_sasl = require "util.sasl".new;
local saslprep = require "util.encodings".stringprep.saslprep;

local log = module._log;
local host = module.host;

local accounts = module:open_store("accounts");

-- define auth provider
local provider = {};

function provider.test_password(username, password)
	log("debug", "test password for user '%s'", username);
	local credentials = accounts:get(username) or {};
	password = saslprep(password);
	if not password then
		return nil, "Password fails SASLprep.";
	end

	if password == saslprep(credentials.password) then
		return true;
	else
		return nil, "Auth failed. Invalid username or password.";
	end
end

function provider.get_password(username)
	log("debug", "get_password for username '%s'", username);
	return (accounts:get(username) or {}).password;
end

function provider.set_password(username, password)
	log("debug", "set_password for username '%s'", username);
	password = saslprep(password);
	if not password then
		return nil, "Password fails SASLprep.";
	end
	local account = accounts:get(username);
	if account then
		account.password = password;
		return accounts:set(username, account);
	end
	return nil, "Account not available.";
end

function provider.user_exists(username)
	local account = accounts:get(username);
	if not account then
		log("debug", "account not found for username '%s'", username);
		return nil, "Auth failed. Invalid username";
	end
	return true;
end

function provider.users()
	return accounts:users();
end

function provider.create_user(username, password)
	password = saslprep(password);
	if not password then
		return nil, "Password fails SASLprep.";
	end
	return accounts:set(username, {password = password});
end

function provider.delete_user(username)
	return accounts:set(username, nil);
end

function provider.get_sasl_handler()
	local getpass_authentication_profile = {
		plain = function(_, username, realm)
			local password = usermanager.get_password(username, realm);
			if not password then
				return "", nil;
			end
			return password, true;
		end
	};
	return new_sasl(host, getpass_authentication_profile);
end

module:provides("auth", provider);