Reworks plugin loading and structure

Implements #4358

scripts/plugins/endpoints/webhook_alert_endpoint/alert_endpoints/webhook.lua

@@ -0,0 +1,152 @@
+--
+-- (C) 2018 - ntop.org
+--
+
+require "lua_utils"
+local json = require "dkjson"
+
+local webhook = {
+   name = "Webhook",
+   conf_params = {
+      { param_name = "webhook_url" },
+      { param_name = "webhook_sharedsecret", optional = true },
+      { param_name = "webhook_username", optional = true },
+      { param_name = "webhook_password", optional = true },
+      -- TODO: configure severity (Errors, Errors and Warnings, All)
+   },
+   conf_template = {
+      plugin_key = "webhook_alert_endpoint",
+      template_name = "webhook_endpoint.template"
+   },
+   recipient_params = {
+   },
+   recipient_template = {
+      plugin_key = "webhook_alert_endpoint",
+      template_name = "webhook_recipient.template"
+   },
+}
+
+webhook.EXPORT_FREQUENCY = 60
+webhook.API_VERSION = "0.2"
+webhook.REQUEST_TIMEOUT = 1
+webhook.ITERATION_TIMEOUT = 3
+webhook.prio = 400
+local MAX_ALERTS_PER_REQUEST = 10
+
+-- ##############################################
+
+local function recipient2sendMessageSettings(recipient)
+  local settings = {
+    url = recipient.endpoint_conf.webhook_url,
+    sharedsecret = recipient.endpoint_conf.webhook_sharedsecret,
+    username = recipient.endpoint_conf.webhook_username,
+    password = recipient.endpoint_conf.webhook_password,
+  }
+
+  return settings
+end
+
+-- ##############################################
+
+function webhook.sendMessage(alerts, settings)
+  if isEmptyString(settings.url) then
+    return false
+  end
+
+  local message = {
+    version = webhook.API_VERSION,
+    sharedsecret = settings.sharedsecret,
+    alerts = alerts,
+  }
+
+  local json_message = json.encode(message)
+
+  local rc = false
+  local retry_attempts = 3
+  while retry_attempts > 0 do
+    if ntop.postHTTPJsonData(settings.username, settings.password, settings.url, json_message, webhook.REQUEST_TIMEOUT) then 
+      rc = true
+      break 
+    end
+    retry_attempts = retry_attempts - 1
+  end
+
+  return rc
+end
+
+-- ##############################################
+
+function webhook.dequeueRecipientAlerts(recipient, budget, high_priority)
+  local start_time = os.time()
+  local sent = 0
+  local more_available = true
+  local budget_used = 0
+
+  local settings = recipient2sendMessageSettings(recipient)
+
+  -- Dequeue alerts up to budget x MAX_ALERTS_PER_REQUEST
+  -- Note: in this case budget is the number of webhook messages to send
+  while budget_used <= budget and more_available do
+
+    local diff = os.time() - start_time
+    if diff >= webhook.ITERATION_TIMEOUT then
+      break
+    end
+
+    -- Dequeue MAX_ALERTS_PER_REQUEST notifications
+    local notifications = {}
+    for i = 1, MAX_ALERTS_PER_REQUEST do
+       local notification = ntop.recipient_dequeue(recipient.recipient_id, high_priority)
+       if notification then 
+	  notifications[#notifications + 1] = notification
+       else
+	  break
+       end
+    end
+
+    if not notifications or #notifications == 0 then
+      more_available = false
+      break
+    end
+
+    local alerts = {}
+
+    for _, json_message in ipairs(notifications) do
+      local alert = json.decode(json_message)
+      table.insert(alerts, alert)
+    end
+
+    if not webhook.sendMessage(alerts, settings) then
+      return {success=false, error_message="Unable to send alerts to the webhook"}
+    end
+
+    -- Remove the processed messages from the queue
+    budget_used = budget_used + #notifications
+    sent = sent + 1
+  end
+
+  return {success = true, more_available = more_available}
+end
+
+-- ##############################################
+
+function webhook.runTest(recipient)
+  local message_info
+
+  local settings = recipient2sendMessageSettings(recipient)
+
+  local success = webhook.sendMessage({}, settings)
+
+  if success then
+    message_info = i18n("prefs.webhook_sent_successfully")
+  else
+    message_info = i18n("prefs.webhook_send_error")
+  end
+
+  return success, message_info
+end
+
+-- ##############################################
+
+return webhook
+