Dynamic Parameters

Author: z-vr

lib/logstash/inputs/http_poller.rb

@@ -5,6 +5,7 @@
 require "socket" # for Socket.gethostname
 require "manticore"
 require "rufus/scheduler"
+require "yaml" # persistence
 
 class LogStash::Inputs::HTTP_Poller < LogStash::Inputs::Base
   include LogStash::PluginMixins::HttpClient
@@ -57,10 +58,15 @@ def setup_requests!
     @requests = Hash[@urls.map {|name, url| [name, normalize_request(url)] }]
   end
 
+  private
+  def filter_dynamic_params(allowed_keys, params)
+    params.slice(*allowed_keys)
+  end
+
   private
   def normalize_request(url_or_spec)
     if url_or_spec.is_a?(String)
-      res = [:get, url_or_spec]
+      res = [:get, url_or_spec, {}]
     elsif url_or_spec.is_a?(Hash)
       # The client will expect keys / values
       spec = Hash[url_or_spec.clone.map {|k,v| [k.to_sym, v] }] # symbolize keys
@@ -77,17 +83,29 @@ def normalize_request(url_or_spec)
       auth = spec[:auth]
       user = spec.delete(:user) || (auth && auth["user"])
       password = spec.delete(:password) || (auth && auth["password"])
-      
+
       if user.nil? ^ password.nil?
         raise LogStash::ConfigurationError, "'user' and 'password' must both be specified for input HTTP poller!"
       end
 
       if user && password
         spec[:auth] = {
-          user: user, 
+          user: user,
           pass: password,
           eager: true
-        } 
+        }
+
+      if spec.delete(:use_dynamic_params)
+        last_dynamic_params_location = spec[:last_dynamic_params]
+        dynamic_params_map = spec[:dynamic_params_map]
+
+        if last_dynamic_params_location.is_a?(String) && File.exist?(last_dynamic_params_location)
+          dynamic_params = YAML.load(File.read(last_dynamic_params_location))
+          allowed_keys = dynamic_params_map.is_a?(Hash) ? dynamic_params_map.keys : []
+          spec[:dynamic_params] = filter_dynamic_params(allowed_keys, dynamic_params)
+        else
+          spec[:dynamic_params] = {}
+        end
       end
       res = [method, url, spec]
     else
@@ -133,13 +151,23 @@ def setup_schedule(queue)
 
     @scheduler = Rufus::Scheduler.new(:max_work_threads => 1)
     #as of v3.0.9, :first_in => :now doesn't work. Use the following workaround instead
-    opts = schedule_type == "every" ? { :first_in => 0.01 } : {} 
+    opts = schedule_type == "every" ? { :first_in => 0.01 } : {}
     @scheduler.send(schedule_type, schedule_value, opts) { run_once(queue) }
     @scheduler.join
   end
 
+  private
+  def assign_dynamic_params(request)
+    params = request[2][:dynamic_params]
+    request[2][:query] = {} if !request[2][:query]
+    params.keys.each do |key|
+      request[2][:query][key] = params[key]
+    end
+  end
+
   def run_once(queue)
     @requests.each do |name, request|
+      assign_dynamic_params(request) if request[2][:dynamic_params]
       request_async(queue, name, request)
     end
 
@@ -175,11 +203,23 @@ def handle_success(queue, name, request, response, execution_time)
     end
   end
 
+  private
+  def update_dynamic_params(request, event)
+    request[2][:dynamic_params_map].keys.each do |key|
+      value = request[2][:dynamic_params_map][key]
+      event_value = event.get(value)
+      request[2][:dynamic_params][key] = event_value if event_value
+    end
+    File.write(request[2][:last_dynamic_params], YAML.dump(request[2][:dynamic_params]))
+  end
+
   private
   def handle_decoded_event(queue, name, request, response, event, execution_time)
     apply_metadata(event, name, request, response, execution_time)
     decorate(event)
     queue << event
+
+    update_dynamic_params(request, event) if request[2][:dynamic_params]
   rescue StandardError, java.lang.Exception => e
     @logger.error? && @logger.error("Error eventifying response!",
                                     :exception => e,