Added alert when dropping flows due to flow exporters limit exceeded

scripts/lua/modules/check_definitions/system/exporters_limit_exceeded.lua

@@ -0,0 +1,45 @@
+--
+-- (C) 2019-24 - ntop.org
+--
+local alerts_api = require("alerts_api")
+local alert_consts = require("alert_consts")
+local alert_categories = require "alert_categories"
+
+local script = {
+    -- Script category
+    category = alert_categories.internals,
+    severity = alert_consts.get_printable_severities().critical,
+
+    -- See below
+    hooks = {},
+
+    gui = {
+        i18n_title = "internals.system_alert_drops",
+        i18n_description = "internals.system_alert_drops_descr"
+    }
+}
+
+local EXPORTERS_LIMITS_EXCEEDED_KEY = "ntopng.limits.exporters"
+
+-- #################################################################
+
+local function dropped_flows_check(params)
+    -- Fetch if an interface dropped some flows due to limits exceeded regarding flow exporters
+    local exporters_limit_exceeded = ntop.getCache(EXPORTERS_LIMITS_EXCEEDED_KEY) or ""
+    tprint(exporters_limit_exceeded)
+    if not isEmptyString(exporters_limit_exceeded) and exporters_limit_exceeded ~= "0" then
+        local alert = alert_consts.alert_types.alert_exporters_limit_exceeded.new()
+        -- Remove the value to not spam the message
+        ntop.setCache(EXPORTERS_LIMITS_EXCEEDED_KEY, "")
+        alert:set_score_emergency()
+        alert:store(alerts_api.systemEntity())
+    end
+end
+
+-- #################################################################
+
+script.hooks.min = dropped_flows_check
+
+-- #################################################################
+
+return script