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util/helpers.lua @ 11523:5f15ab7c6ae5
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
author | Jonas Schäfer <jonas@wielicki.name> |
---|---|
date | Sun, 18 Apr 2021 11:47:41 +0200 (2021-04-18) |
parent | 11059:ad89e3cc67b6 |
child | 12975:d10957394a3c |
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-- 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 debug = require "util.debug"; -- Helper functions for debugging local log = require "util.logger".init("util.debug"); local function log_events(events, name, logger) local f = events.fire_event; if not f then error("Object does not appear to be a util.events object"); end logger = logger or log; name = name or tostring(events); function events.fire_event(event, ...) logger("debug", "%s firing event: %s", name, event); return f(event, ...); end local function event_handler_hook(handler, event_name, event_data) logger("debug", "calling handler for %s: %s", event_name, handler); local ok, ret = pcall(handler, event_data); if not ok then logger("error", "error in event handler %s: %s", handler, ret); error(ret); end if ret ~= nil then logger("debug", "event chain ended for %s by %s with result: %s", event_name, handler, ret); end return ret; end events.set_debug_hook(event_handler_hook); events[events.fire_event] = f; return events; end local function revert_log_events(events) events.fire_event, events[events.fire_event] = events[events.fire_event], nil; -- :)) events.set_debug_hook(nil); end local function log_host_events(host) return log_events(prosody.hosts[host].events, host); end local function revert_log_host_events(host) return revert_log_events(prosody.hosts[host].events); end local function show_events(events, specific_event) local event_handlers = events._handlers; local events_array = {}; local event_handler_arrays = {}; for event, priorities in pairs(events._event_map) do local handlers = event_handlers[event]; if handlers and (event == specific_event or not specific_event) then table.insert(events_array, event); local handler_strings = {}; for i, handler in ipairs(handlers) do local upvals = debug.string_from_var_table(debug.get_upvalues_table(handler)); handler_strings[i] = " "..(priorities[handler] or "?")..": "..tostring(handler)..(upvals and ("\n "..upvals) or ""); end event_handler_arrays[event] = handler_strings; end end table.sort(events_array); local i = 1; while i <= #events_array do local handlers = event_handler_arrays[events_array[i]]; for j=#handlers, 1, -1 do table.insert(events_array, i+1, handlers[j]); end if i > 1 then events_array[i] = "\n"..events_array[i]; end i = i + #handlers + 1 end return table.concat(events_array, "\n"); end local function get_upvalue(f, get_name) local i, name, value = 0; repeat i = i + 1; name, value = debug.getupvalue(f, i); until name == get_name or name == nil; return value; end return { log_host_events = log_host_events; revert_log_host_events = revert_log_host_events; log_events = log_events; revert_log_events = revert_log_events; show_events = show_events; get_upvalue = get_upvalue; };