add support for streaming logs to elasticsearch via a "rabbitmq river".

we have to PUT a json config to the elasticsearch HTTP API to tell it
where to look, then we use our amqp output to send bulk-data style
index messages to elasticsearch. The ES side does bulk-queueing for us.

etc/logstash-elasticsearch-rabbitmq-river.yaml

@@ -0,0 +1,41 @@
+--- 
+# this is a sample logstash config (code is still highly in change, so
+# this could change later)
+#
+#
+inputs:
+# Give a list of inputs. Tag them for easy query/filter later.
+  linux-syslog: # this is the 'linux-syslog' type
+  - /var/log/messages # watch /var/log/messages (uses eventmachine-tail)
+  - /var/log/kern.log
+  - /var/log/auth.log
+  - /var/log/user.log
+  apache-access: # similar, different type.
+  - /var/log/apache2/access.log
+  - /b/access
+  apache-error:
+  - /var/log/apache2/error.log
+filters:
+- grok:
+    linux-syslog: # for logs of type 'linux-syslog'
+      patterns:
+      - %{SYSLOGLINE}
+    apache-access: # for logs of type 'apache-error'
+      patterns:
+      - %{COMBINEDAPACHELOG}
+- date:
+    linux-syslog:  # for logs of type 'linux-syslog'
+      # Look for a field 'timestamp' with this format, parse and it for the timestamp
+      # This field comes from the SYSLOGLINE pattern
+      timestamp: "%b %e %H:%M:%S"
+    apache-access:
+      timestamp: "%d/%b/%Y:%H:%M:%S %Z"
+outputs:
+- stdout:///
+- "elasticsearch://localhost:9200/logs/all?method=river&type=rabbitmq&host=127.0.0.1&user=guest&pass=guest&vhost=/&queue=es"
+# But we could write to mongodb, too.
+#  - mongodb://localhost/parsedlogs
+# And also write to an AMQP topic
+#  - amqp://localhost/topic/parsedlogs
+# Write to stdout ... etc.
+# - stdout:///

lib/logstash/outputs/elasticsearch.rb

@@ -1,4 +1,5 @@
 require "logstash/outputs/base"
+require "logstash/outputs/amqp"
 require "em-http-request"
 
 class LogStash::Outputs::Elasticsearch < LogStash::Outputs::Base
@@ -11,13 +12,59 @@ class LogStash::Outputs::Elasticsearch < LogStash::Outputs::Base
     # Authentication?
     @httpurl = @url.clone
     @httpurl.scheme = "http"
-    @http = EventMachine::HttpRequest.new(@httpurl.to_s)
+    defaults = {"method" => "http"}
+    params = defaults.merge(@urlopts)
+
+    case params["method"]
+    when "http"
+      @logger.debug "ElasticSearch using http with URL #{@httpurl.to_s}"
+      @http = EventMachine::HttpRequest.new(@httpurl.to_s)
+      @callback = self.method(:receive_http)
+    when "river"
+      mq_url = URI::parse("amqp://#{params["host"]}/queue/#{params["queue"]}?durable=1")
+      @mq = LogStash::Outputs::Amqp.new(mq_url.to_s)
+      @mq.register
+      @callback = self.method(:receive_river)
+      em_url = URI.parse("http://#{@httpurl.host}:#{@httpurl.port}/_river/logstash#{@httpurl.path.tr("/", "_")}/_meta")
+      unused, @es_index, @es_type = @httpurl.path.split("/", 3)
+
+      river_config = {"type" => params["type"],
+                      params["type"] => {"host" => params["host"],
+                                         "user" => params["user"],
+                                         "pass" => params["pass"],
+                                         "vhost" => params["vhost"],
+                                         "queue" => params["queue"],
+                                         "exchange" => params["queue"],
+                                        },
+                     "index" => {"bulk_size" => 100,
+                                 "bulk_timeout" => "10ms",
+                                },
+                     }
+      @logger.debug "ElasticSearch using river with config #{river_config.awesome_inspect}"
+      http_setup = EventMachine::HttpRequest.new(em_url.to_s)
+      req = http_setup.put :body => river_config.to_json
+      req.errback do
+        @logger.warn "Error setting up river: #{req.response}"
+      end
+    else raise "unknown elasticsearch method #{params["method"].inspect}"
+    end
   end # def register
 
   def receive(event)
+    @callback.call(event)
+  end # def receive
+
+  def receive_http(event)
     req = @http.post :body => event.to_json
     req.errback do
       $stderr.puts "Request to index to #{@httpurl.to_s} failed. Event was #{event.to_s}"
     end
-  end # def event
+  end # def receive_http
+
+  def receive_river(event)
+    # bulk format; see http://www.elasticsearch.com/docs/elasticsearch/river/rabbitmq/
+    index_message = {"index" => {"_index" => @es_index, "_type" => @es_type}}.to_json + "\n"
+    index_message += {@es_type => event.to_hash}.to_json + "\n"
+    @mq.receive_raw(index_message)
+  end # def receive_river
 end # class LogStash::Outputs::Websocket