EventMachine connection handler for the Sensu client's socket.
The Sensu client listens on localhost, port 3030 (by default), for UDP and TCP traffic. This allows software running on the host to push check results (that may contain metrics) into Sensu, without needing to know anything about Sensu's internal implementation.
The socket only accepts 7-bit ASCII-encoded data.
Although the Sensu client accepts UDP and TCP traffic, you must be aware of the UDP protocol limitations. Any data you send over UDP must fit in a single datagram and you will not receive a response (no confirmation).
If the socket receives a message containing whitespace and the string +'ping'+, it will ignore it.
The socket assumes all other messages will contain a single, complete, JSON hash. The hash must be a valid JSON check result. Deserialization failures will be logged at the ERROR level by the Sensu client, but the sender of the invalid data will not be notified.
If the socket receives a message containing whitespace and the string +'ping'+, it will respond with the message +'pong'+.
The socket assumes any other stream will be a single, complete, JSON hash. A deserialization failure will be logged at the WARN level by the Sensu client and respond with the message +'invalid'+. An +'ok'+ response indicates the Sensu client successfully received the JSON hash and will publish the check result.
Streams can be of any length. The socket protocol does not require any
headers, instead the socket tries to parse everything it has been sent each
time a chunk of data arrives. Once the JSON parses successfully, the Sensu client publishes the result. After
WATCHDOG_DELAY
(default is 500 msec) since the most recent
chunk of data was received, the agent will give up on the sender, and
instead respond +'invalid'+ and close the connection.
ACCEPT mode. Append chunks of data to a buffer and test to see whether the buffer contents are valid JSON.
REJECT mode. No longer receiving data from sender. Discard chunks of data in this mode, the connection is being closed.
The number of seconds that may elapse between chunks of data from a sender before it is considered dead, and the connection is close.
Cancel the current connection watchdog.
# File lib/sensu/socket.rb, line 95 def cancel_watchdog if @watchdog @watchdog.cancel end end
Parse a JSON check result. For UDP, immediately raise a parser error. For
TCP, record parser errors, so the connection watchdog
can
report them.
@param [String] data to parse for a check result.
# File lib/sensu/socket.rb, line 161 def parse_check_result(data) begin check = MultiJson.load(data) cancel_watchdog process_check_result(check) rescue MultiJson::ParseError, ArgumentError => error if @protocol == :tcp @parse_error = error.to_s else raise error end end end
Initialize instance variables that will be used throughout the lifetime of the connection. This method is called when the network connection has been established, and immediately after responding to a sender.
# File lib/sensu/socket.rb, line 74 def post_init @protocol ||= :tcp @data_buffer = '' @parse_error = nil @watchdog = nil @mode = MODE_ACCEPT end
Process a check result. Set check result attribute defaults, validate the attributes, publish the check result to the Sensu transport, and respond to the sender with the message +'ok'+.
@param [Hash] check result to be validated and published. @raise
[DataError] if check
is invalid.
# File lib/sensu/socket.rb, line 149 def process_check_result(check) check[:status] ||= 0 validate_check_result(check) publish_check_result(check) respond('ok') end
Process the data received. This method validates the data encoding, provides ping/pong functionality, and passes potential check results on for further processing.
@param [String] data to be processed.
# File lib/sensu/socket.rb, line 180 def process_data(data) if data.bytes.find { |char| char > 0x80 } @logger.warn('socket received non-ascii characters') respond('invalid') elsif data.strip == 'ping' @logger.debug('socket received ping') respond('pong') else @logger.debug('socket received data', { :data => data }) begin parse_check_result(data) rescue => error @logger.error('failed to process check result from socket', { :data => data, :error => error.to_s }) respond('invalid') end end end
Publish a check result to the Sensu transport.
@param [Hash] check result.
# File lib/sensu/socket.rb, line 132 def publish_check_result(check) payload = { :client => @settings[:client][:name], :check => check.merge(:issued => Time.now.to_i) } @logger.info('publishing check result', { :payload => payload }) @transport.publish(:direct, 'results', MultiJson.dump(payload)) end
This method is called whenever data is received. For UDP, it will only be
called once, the original data length can be expected. For TCP, this method
may be called several times, data received is buffered. TCP connections
require a watchdog
.
@param [String] data received from the sender.
# File lib/sensu/socket.rb, line 209 def receive_data(data) unless @mode == MODE_REJECT case @protocol when :udp process_data(data) when :tcp if EM.reactor_running? reset_watchdog end @data_buffer << data process_data(@data_buffer) end end end
Reset (or start) the connection watchdog.
# File lib/sensu/socket.rb, line 102 def reset_watchdog cancel_watchdog @watchdog = EM::Timer.new(WATCHDOG_DELAY) do @mode = MODE_REJECT @logger.warn('discarding data buffer for sender and closing connection', { :data => @data_buffer, :parse_error => @parse_error }) respond('invalid') end end
Send a response to the sender, close the connection, and call #post_init().
@param [String] data to send as a response.
# File lib/sensu/socket.rb, line 86 def respond(data) if @protocol == :tcp send_data(data) close_connection_after_writing end post_init end
Validate check result attributes.
@param [Hash] check result to validate.
# File lib/sensu/socket.rb, line 117 def validate_check_result(check) unless check[:name] =~ /^[\w\.-]+$/ raise DataError, 'check name must be a string and cannot contain spaces or special characters' end unless check[:output].is_a?(String) raise DataError, 'check output must be a string' end unless check[:status].is_a?(Integer) raise DataError, 'check status must be an integer' end end