Add Tarantool metrics

Author: Konstantin Nazarov

example.lua

@@ -5,6 +5,7 @@ prometheus = require('tarantool-prometheus')
 fiber = require('fiber')
 
 box.cfg{}
+prometheus.init()
 
 httpd = http.new('0.0.0.0', 8080)
 

tarantool-metrics.lua

@@ -0,0 +1,61 @@
+#!/usr/bin/env tarantool
+
+local prometheus = require('tarantool-prometheus')
+
+local memory_limit_bytes = prometheus.gauge(
+    'tarantool_memory_limit_bytes',
+    'Maximum amount of memory Tarantool can use')
+local memory_used_bytes = prometheus.gauge(
+    'tarantool_memory_used_bytes',
+    'Amount of memory currently used by Tarantool')
+local tuples_memory_bytes = prometheus.gauge(
+    'tarantool_tuples_memory_bytes',
+    'Amount of memory allocated for Tarantool tuples')
+local system_memory_bytes = prometheus.gauge(
+    'tarantool_system_memory_bytes',
+    'Amount of memory used by Tarantool indexes and system')
+
+local requests_total = prometheus.gauge(
+    'tarantool_requests_total',
+    'Total number of requests by request type',
+    {'request_type'})
+
+local uptime_seconds = prometheus.gauge(
+    'tarantool_uptime_seconds',
+    'Number of seconds since the server started')
+
+local function measure_tarantool_memory_usage()
+    local slabs = box.slab.info()
+    local memory_limit = slabs.quota_size
+    local memory_used = slabs.quota_used
+    local tuples_memory = slabs.arena_used
+    local system_memory = memory_used - tuples_memory
+
+    memory_limit_bytes:set(memory_limit)
+    memory_used_bytes:set(memory_used)
+    tuples_memory_bytes:set(tuples_memory)
+    system_memory_bytes:set(system_memory)
+end
+
+local function measure_tarantool_request_stats()
+    local stat = box.stat()
+    local request_types = {'delete', 'select', 'insert', 'eval', 'call',
+                           'replace', 'upsert', 'auth', 'error', 'update'}
+
+    for _, request_type in ipairs(request_types) do
+        requests_total:set(stat[string.upper(request_type)].total,
+                           {request_type})
+    end
+end
+
+local function measure_tarantool_uptime()
+    uptime_seconds:set(box.info.uptime)
+end
+
+local function measure_tarantool_metrics()
+    measure_tarantool_memory_usage()
+    measure_tarantool_request_stats()
+    measure_tarantool_uptime()
+end
+
+return {measure_tarantool_metrics=measure_tarantool_metrics}

tarantool-prometheus.lua

@@ -14,6 +14,7 @@ function Registry.new()
     local obj = {}
     setmetatable(obj, Registry)
     obj.collectors = {}
+    obj.callbacks = {}
     return obj
 end
 
@@ -32,6 +33,10 @@ function Registry:unregister(collector)
 end
 
 function Registry:collect()
+    for _, registered_callback in ipairs(self.callbacks) do
+        registered_callback()
+    end
+
     local result = {}
     for _, collector in pairs(self.collectors) do
         for _, metric in ipairs(collector:collect()) do
@@ -41,6 +46,18 @@ function Registry:collect()
     return result
 end
 
+function Registry:register_callback(callback)
+    local found = false
+    for _, registered_callback in ipairs(self.callbacks) do
+        if registered_callback == calback then
+            found = true
+        end
+    end
+    if not found then
+        table.insert(self.callbacks, callback)
+    end
+end
+
 local function get_registry()
     if not REGISTRY then
         REGISTRY = Registry.new()
@@ -55,6 +72,11 @@ local function register(collector)
     return collector
 end
 
+local function register_callback(callback)
+    local registry = get_registry()
+    registry:register_callback(callback)
+end
+
 function zip(lhs, rhs)
     if lhs == nil or rhs == nil then
         return {}
@@ -347,13 +369,21 @@ local function collect_http()
 end
 
 local function clear()
-    registry = get_registry()
+    local registry = get_registry()
     registry.collectors = {}
+    registry.callbacks = {}
+end
+
+local function init()
+    local registry = get_registry()
+    local tarantool_metrics = require('tarantool-metrics')
+    registry:register_callback(tarantool_metrics.measure_tarantool_metrics)
 end
 
 return {counter=counter,
         gauge=gauge,
         histogram=histogram,
         collect=collect,
         collect_http=collect_http,
-        clear=clear}
+        clear=clear,
+        init=init}