Example rework of endpoint slack

scripts/lua/modules/notifications/endpoints/slack.lua

@@ -0,0 +1,173 @@
+--
+-- (C) 2021 - ntop.org
+--
+
+require "lua_utils"
+local json = require "dkjson"
+local alert_consts = require("alert_consts")
+local alert_utils = require "alert_utils"
+
+local slack = {
+   name = "Slack",
+   endpoint_params = {
+      { param_name = "slack_sender_username" },
+      { param_name = "slack_webhook" },
+      -- TODO: add severity (Errors, Errors and Warnings, All)
+   },
+   endpoint_template = {
+      plugin_key = "slack_alert_endpoint",
+      template_name = "slack_endpoint.template"
+   },
+   recipient_params = {
+      -- TODO: add channel
+   },
+   recipient_template = {
+      plugin_key = "slack_alert_endpoint",
+      template_name = "slack_recipient.template" -- TODO: add template
+   },
+}
+
+slack.EXPORT_FREQUENCY = 5
+slack.prio = 500
+local MAX_ALERTS_PER_MESSAGE = 5
+
+local alert_severity_to_emoji = {
+  ["info"] = ":information_source:",
+  ["warning"] = ":warning:",
+  ["error"] = ":exclamation:",
+
+  default = ":warning:",
+}
+
+-- ##############################################
+
+-- @brief Returns the desided formatted output for recipient params
+function slack.format_recipient_params(recipient_params)
+   return string.format("(%s)", slack.name)
+end
+
+-- ##############################################
+
+local function recipient2sendMessageSettings(recipient)
+  local settings = {
+    webhook = recipient.endpoint_conf.slack_webhook,
+    sender_username = recipient.endpoint_conf.slack_sender_username,
+  }
+
+  return settings
+end
+
+-- ##############################################
+
+function slack.sendMessage(entity_type, severity, text, settings)
+  local channel_name = entity_type
+
+  if isEmptyString(settings.webhook) or isEmptyString(settings.sender_username) then
+    return false
+  end
+
+  local message = {
+    icon_emoji = alert_severity_to_emoji[severity] or alert_severity_to_emoji.default,
+    username = settings.sender_username .. " [" .. string.upper(severity)  .. "]",
+    text = text,
+  }
+
+  local json_message = json.encode(message)
+  return ntop.postHTTPJsonData("", "", settings.webhook, json_message)
+end
+
+-- ##############################################
+
+-- This will try to send the most recent MAX_ALERTS_PER_MESSAGE messages for every
+-- channel and severity (no more than one message for each, budget is ignored). 
+-- On success, it clears the queue.
+-- On error, it leaves the queue unchagned to retry on next round.
+function slack.dequeueRecipientAlerts(recipient, budget, high_priority)
+   local notifications = {}
+   for i = 1, budget do
+      local notification = ntop.recipient_dequeue(recipient.recipient_id, high_priority)
+      if notification then 
+	 notifications[#notifications + 1] = notification.alert
+      else
+	 break
+      end
+   end
+
+  if not notifications or #notifications == 0 then
+    return {success = true, more_available = false}
+  end
+
+  local settings = recipient2sendMessageSettings(recipient)
+
+  -- Separate by severity and channel
+  local alerts_by_types = {}
+
+  for _, json_message in ipairs(notifications) do
+    local notif = json.decode(json_message)
+    notif.severity = ntop.mapScoreToSeverity(notif.score)
+    if notif.entity_id then
+      if not alerts_by_types[notif.entity_id] then
+        alerts_by_types[notif.entity_id] = {}
+      end
+      if not alerts_by_types[notif.entity_id][notif.severity] then
+        alerts_by_types[notif.entity_id][notif.severity] = {}
+      end
+      table.insert(alerts_by_types[notif.entity_id][notif.severity], notif)
+    end
+  end
+
+  for entity_type, by_severity in pairs(alerts_by_types) do
+    for severity, notifications in pairs(by_severity) do
+      local messages = {}
+      entity_type = alert_consts.alertEntityRaw(entity_type)
+      severity = alert_consts.alertSeverityRaw(severity)
+
+      -- Most recent notifications first
+      for _, notif in pairsByValues(notifications, alert_utils.notification_timestamp_rev) do
+        local msg = alert_utils.formatAlertNotification(notif, {nohtml=true, show_severity=false, show_entity=true})
+        table.insert(messages, msg)
+
+        if #messages >= MAX_ALERTS_PER_MESSAGE then
+          break
+        end
+      end
+
+      local missing = #notifications - #messages
+
+      if missing > 0 then
+        table.insert(messages, "NOTE: " .. missing .. " older messages have been suppressed")
+      end
+
+      messages = table.concat(messages, "\n")
+
+      if not slack.sendMessage(entity_type, severity, messages, settings) then
+        -- Note: upon failure we'll possibly resend already sent messages
+        return {success=false, error_message="Unable to send slack messages"}
+      end
+    end
+  end
+
+  return {success = true, more_available = true}
+end
+
+-- ##############################################
+
+function slack.runTest(recipient)
+  local message_info
+
+  local settings = recipient2sendMessageSettings(recipient)
+
+  local success = slack.sendMessage("interface", "info", "Slack notification is working", settings)
+
+  if success then
+    message_info = i18n("prefs.slack_sent_successfully", {channel="info"})
+  else
+    message_info = i18n("prefs.slack_send_error")
+  end
+
+  return success, message_info
+end
+
+-- ##############################################
+
+return slack