Reworks plugin loading and structure

Implements #4358

scripts/plugins/examples/example/user_scripts/system/example.lua

@@ -0,0 +1,143 @@
+--
+-- (C) 2019-20 - ntop.org
+--
+
+local alert_consts = require("alert_consts")
+local alerts_api = require("alerts_api")
+
+-- This is a user script executed by scripts/callbacks/system/system.lua .
+-- Changes to this script must be applied by reloading the plugins from
+-- http://127.0.0.1:3000/lua/plugins_overview.lua
+
+local global_state = nil
+
+-- #################################################################
+
+local script = {
+  -- Script category, see user_scripts.script_categories for all available categories
+  category = user_scripts.script_categories.other,
+
+  -- This module is enabled by default
+  default_enabled = true,
+
+  -- The default configuration for this plugin. The current configuration
+  -- is passed to the script hooks as the second parameter.
+  default_value = {
+    -- This configuration is specific of this script
+    ip_address = "8.8.8.8",
+    v6 = false,
+  },
+
+  -- A user script must be attached some hooks in order to be executed.
+  -- This is only a placeholder, see below for the hooks definitions.
+  -- NOTE: the "all" hook is a virtual hook which causes the script to
+  -- be attached to all the available hooks.
+  hooks = {},
+
+  -- GUI specific stuff. If this section is missing, the user script
+  -- will not be shown in the gui.
+  gui = {
+    -- A title for this user script
+    i18n_title = "example.interface_script_title",
+
+    -- A description for this user script
+    i18n_description = "example.interface_script_description",
+  },
+
+  ----------------------------------------------------------------------
+
+  -- If true, the script will be automatically disabled when alerts are
+  -- disabled.
+  is_alert = false,
+
+  -- If true, this script will only be executed on packet interfaces
+  packet_interface_only = false,
+
+  -- If true, this script will only be executed in nEdge
+  nedge_only = false,
+
+  -- If true, this script will not be executed in nEdge
+  nedge_exclude = false,
+
+  -- If true, this script will not be available on Windows.
+  windows_exclude = false,
+}
+
+-- #################################################################
+
+-- @brief Called when the script is going to be loaded.
+-- @return true if the script should be loaded, false otherwise
+-- @notes Can be used to init some script global state or to skip the script
+-- execution on some particular conditions
+function script.setup()
+  local is_enabled = true -- your custom condition here
+
+  global_state = {}
+
+  return(is_enabled)
+end
+
+-- #################################################################
+
+-- An hook executed every minute.
+function script.hooks.min(info)
+  --tprint(info)
+  print("system:min hook called")
+
+  ntop.pingHost(info.user_script_config.ip_address, info.user_script_config.v6)
+
+  -- Wait results
+  ntop.msleep(2000)
+
+  local res = ntop.collectPingResults()
+
+  -- The alert entity must be built manually for system scripts
+  local alert_entity = {
+    alert_entity = alert_consts.alert_entities.am_host,
+    alert_entity_val = info.user_script_config.ip_address,
+  }
+
+  local alert_info = {
+    alert_type = alert_consts.alert_types.alert_example,
+    alert_severity = alert_consts.alert_severities.info,
+    alert_granularity = info.granularity,
+    alert_type_params = {},
+  }
+
+  if(res[info.user_script_config.ip_address] ~= nil) then
+    print(string.format("Host %s is active", info.user_script_config.ip_address))
+
+    -- Release previously triggered alert (if any)
+    alerts_api.release(alert_entity, alert_info)
+  else
+    print(string.format("Host %s is down", info.user_script_config.ip_address))
+
+    -- Trigger alert
+    alerts_api.trigger(alert_entity, alert_info)
+  end
+end
+
+-- #################################################################
+
+-- An hook executed every 5 minutes.
+script.hooks["5mins"] = function(info)
+  print("system:5mins hook called")
+end
+
+-- #################################################################
+
+-- An hook executed every hour.
+function script.hooks.hour(info)
+  print("system:hour hook called")
+end
+
+-- #################################################################
+
+-- An hook executed every day.
+function script.hooks.day(info)
+  print("system:day hook called")
+end
+
+-- #################################################################
+
+return script