box: configure metrics with box.cfg

metrics.cfg is a module configuration entrypoint [1]. After this patch,
box.cfg{metrics = cfg} triggers metrics.cfg. Parameter is dynamic.

This patch also enables all metrics by default. To disable them, use
box.cfg{metrics = {include = 'none'}}. Since callbacks are triggered
manually (when user calls `invoke_callbacks()` or
`collect{invoke_callbacks=true}`), it should not affect
the performance.

1. https://www.tarantool.io/en/doc/latest/book/monitoring/api_reference/#lua-function.metrics.cfg

Closes #7725

@TarantoolBot document
Title: embedded metrics configuration

This patch add new box.cfg dynamic parameter: metrics. It is a table
with the same effect as in metrics.cfg. metrics.cfg has its own
documentation, see [1].

1. https://www.tarantool.io/en/doc/latest/book/monitoring/api_reference/#lua-function.metrics.cfg

changelogs/unreleased/gh-7725-embed-metrics.md

@@ -1,3 +1,4 @@
 ## feature/lua
 
 * Embed tarantool/metrics module for metrics aggregation and export (gh-7725).
+* Configure metrics with box.cfg (gh-7725).

src/box/lua/load_cfg.lua

@@ -193,6 +193,12 @@ local default_cfg = {
     sql_cache_size        = 5 * 1024 * 1024,
     txn_timeout           = 365 * 100 * 86400,
     txn_isolation         = "best-effort",
+
+    metrics     = {
+        include = 'all',
+        exclude = {},
+        labels = {},
+    },
 }
 
 -- We need to track cfg changes done through API of distinct modules (log.cfg of
@@ -377,6 +383,8 @@ local template_cfg = {
     net_msg_max           = 'number',
     sql_cache_size        = 'number',
     txn_timeout           = 'number',
+
+    metrics = 'table',
 }
 
 local function normalize_uri_list_for_replication(port_list)
@@ -492,7 +500,11 @@ local dynamic_cfg = {
     password_enforce_digits = ifdef_security(nop),
     password_enforce_specialchars = ifdef_security(nop),
     password_history_length = ifdef_security(nop),
-    wal_ext                 = private.cfg_set_wal_ext
+    wal_ext                 = private.cfg_set_wal_ext,
+
+    metrics = function()
+        require('metrics').cfg(box.cfg.metrics)
+    end,
 }
 
 -- The modules that can apply all new options with single call. The

test/box-luatest/gh_8192_feedback_daemon_metrics_test.lua

@@ -6,6 +6,7 @@ g.before_all(function()
     g.server = server:new{
         alias = 'default',
         box_cfg = {
+            metrics = {include = 'none'},
             -- The tests here are unit ones, works with dummy metrics
             -- package. After metrics package embedding, feedback background
             -- loop may succeed to extract empty metrics table from

test/box/admin.result

@@ -87,6 +87,13 @@ cfg_filter(box.cfg)
     - <hidden>
   - - memtx_use_mvcc_engine
     - false
+  - - metrics
+    - - - exclude
+        - []
+      - - include
+        - all
+      - - labels
+        - []
   - - net_msg_max
     - 768
   - - pid_file

test/box/cfg.result

@@ -75,6 +75,13 @@ cfg_filter(box.cfg)
  |     - <hidden>
  |   - - memtx_use_mvcc_engine
  |     - false
+ |   - - metrics
+ |     - - - exclude
+ |         - []
+ |       - - include
+ |         - all
+ |       - - labels
+ |         - []
  |   - - net_msg_max
  |     - 768
  |   - - pid_file
@@ -220,6 +227,13 @@ cfg_filter(box.cfg)
  |     - <hidden>
  |   - - memtx_use_mvcc_engine
  |     - false
+ |   - - metrics
+ |     - - - exclude
+ |         - []
+ |       - - include
+ |         - all
+ |       - - labels
+ |         - []
  |   - - net_msg_max
  |     - 768
  |   - - pid_file

test/metrics-luatest/box_cfg_test.lua

@@ -0,0 +1,124 @@
+require('test.metrics-luatest.helper')
+
+local t = require('luatest')
+local g = t.group('box-cfg-metrics')
+local server = require('luatest.server')
+
+local utils = require('third_party.metrics.test.utils')
+
+g.before_all(function()
+    g.server = server:new()
+    g.server:start()
+end)
+
+g.after_all(function()
+    g.server:drop()
+end)
+
+g.before_each(function()
+    g.server:exec(function()
+        box.cfg{
+            metrics = {
+                include = 'all',
+                exclude = {},
+                labels = {},
+            }
+        }
+    end)
+end)
+
+g.test_include = function()
+    local default_metrics = g.server:exec(function()
+        box.cfg{
+            metrics = {
+                include = {'info'},
+            }
+        }
+
+        return require('metrics').collect{invoke_callbacks = true}
+    end)
+
+    local uptime = utils.find_metric('tnt_info_uptime', default_metrics)
+    t.assert_not_equals(uptime, nil)
+    local memlua = utils.find_metric('tnt_info_memory_lua', default_metrics)
+    t.assert_equals(memlua, nil)
+end
+
+g.test_exclude = function()
+    local default_metrics = g.server:exec(function()
+        box.cfg{
+            metrics = {
+                exclude = {'memory'},
+            }
+        }
+
+        return require('metrics').collect{invoke_callbacks = true}
+    end)
+
+    local uptime = utils.find_metric('tnt_info_uptime', default_metrics)
+    t.assert_not_equals(uptime, nil)
+    local memlua = utils.find_metric('tnt_info_memory_lua', default_metrics)
+    t.assert_equals(memlua, nil)
+end
+
+g.test_include_with_exclude = function()
+    local default_metrics = g.server:exec(function()
+        box.cfg{
+            metrics = {
+                include = {'info', 'memory'},
+                exclude = {'memory'},
+            }
+        }
+
+        return require('metrics').collect{invoke_callbacks = true}
+    end)
+
+    local uptime = utils.find_metric('tnt_info_uptime', default_metrics)
+    t.assert_not_equals(uptime, nil)
+    local memlua = utils.find_metric('tnt_info_memory_lua', default_metrics)
+    t.assert_equals(memlua, nil)
+end
+
+g.test_include_none = function()
+    local default_metrics = g.server:exec(function()
+        box.cfg{
+            metrics = {
+                include = 'none',
+                exclude = {'memory'},
+            }
+        }
+
+        return require('metrics').collect{invoke_callbacks = true}
+    end)
+
+    t.assert_equals(default_metrics, {})
+end
+
+g.test_labels = function()
+    local default_metrics = g.server:exec(function()
+        box.cfg{
+            metrics = {
+                labels = {mylabel = 'myvalue'}
+            }
+        }
+
+        return require('metrics').collect{invoke_callbacks = true}
+    end)
+
+    local uptime = utils.find_obs('tnt_info_uptime', {mylabel = 'myvalue'},
+                                  default_metrics)
+    t.assert_equals(uptime.label_pairs, {mylabel = 'myvalue'})
+
+    default_metrics = g.server:exec(function()
+        box.cfg{
+            metrics = {
+                labels = {}
+            }
+        }
+
+        return require('metrics').collect{invoke_callbacks = true}
+    end)
+
+    uptime = utils.find_obs('tnt_info_uptime', {}, default_metrics)
+    t.assert_equals(uptime.label_pairs, {})
+end