Implemented connection failed alert (#6622)

scripts/lua/modules/alert_definitions/flow/alert_connection_failed.lua

@@ -0,0 +1,51 @@
+--
+-- (C) 2019-22 - ntop.org
+--
+
+-- ##############################################
+
+local flow_alert_keys = require "flow_alert_keys"
+-- Import the classes library.
+local classes = require "classes"
+-- Make sure to import the Superclass!
+local alert = require "alert"
+
+-- ##############################################
+
+local alert_connection_failed = classes.class(alert)
+
+-- ##############################################
+
+alert_connection_failed.meta = {
+   alert_key = flow_alert_keys.flow_alert_connection_failed,
+   i18n_title = "flow_checks_config.connection_failed_title",
+   icon = "fas fa-fw fa-exclamation",
+}
+
+-- ##############################################
+
+-- @brief Prepare an alert table used to generate the alert
+-- @param connection_failed_threshold Threshold, in seconds, for a flow to be considered connection_failed
+-- @return A table with the alert built
+function alert_connection_failed:init()
+  -- Call the parent constructor
+  self.super:init()
+end
+
+-- #######################################################
+
+-- @brief Format an alert into a human-readable string
+-- @param ifid The integer interface id of the generated alert
+-- @param alert The alert description table, including alert data such as the generating entity, timestamp, granularity, type
+-- @param alert_type_params Table `alert_type_params` as built in the `:init` method
+-- @return A human-readable string
+function alert_connection_failed.format(ifid, alert, alert_type_params)
+  local cli = format_alert_hostname(alert, "cli")
+  local srv = format_alert_hostname(alert, "srv")
+  
+  return i18n("flow_details.connection_failed_descr", { cli = cli, srv = srv })   
+end
+
+-- #######################################################
+
+return alert_connection_failed