class Sensu::Client::Process

Attributes

safe_mode[RW]

Public Class Methods

new(options={}) click to toggle source

Override Daemon initialize() to support Sensu client check execution safe mode, checks in progress, and open sockets.

@param options [Hash]

Calls superclass method Sensu::Daemon.new
# File lib/sensu/client/process.rb, line 28
def initialize(options={})
  super
  @safe_mode = @settings[:client][:safe_mode] || false
  @checks_in_progress = []
  @sockets = []
end
run(options={}) click to toggle source

Create an instance of the Sensu client process, start the client within the EventMachine event loop, and set up client process signal traps (for stopping).

@param options [Hash]

# File lib/sensu/client/process.rb, line 16
def self.run(options={})
  client = self.new(options)
  EM::run do
    client.start
    client.setup_signal_traps
  end
end

Public Instance Methods

bootstrap() click to toggle source

Bootstrap the Sensu client, setting up client keepalives, subscriptions, and standalone check executions. This method sets the process/daemon `@state` to `:running`.

# File lib/sensu/client/process.rb, line 368
def bootstrap
  setup_keepalives
  setup_subscriptions
  setup_standalone
  @state = :running
end
calculate_execution_splay(check) click to toggle source

Calculate a check execution splay, taking into account the current time and the execution interval to ensure it's consistent between process restarts.

@param check [Hash] definition.

# File lib/sensu/client/process.rb, line 258
def calculate_execution_splay(check)
  key = [@settings[:client][:name], check[:name]].join(":")
  splay_hash = Digest::MD5.digest(key).unpack("Q<").first
  current_time = (Time.now.to_f * 1000).to_i
  (splay_hash - current_time) % (check[:interval] * 1000) / 1000.0
end
close_sockets() click to toggle source

Close the Sensu client TCP and UDP sockets. This method iterates through `@sockets`, which contains socket server signatures (Fixnum) and connection objects. A signature indicates a TCP socket server that needs to be stopped. A connection object indicates a socket connection that needs to be closed, eg. a UDP datagram socket.

# File lib/sensu/client/process.rb, line 354
def close_sockets
  @logger.info("closing client tcp and udp sockets")
  @sockets.each do |socket|
    if socket.is_a?(Numeric)
      EM.stop_server(socket)
    else
      socket.close_connection
    end
  end
end
complete_checks_in_progress() { || ... } click to toggle source

Call a callback (Ruby block) when there are no longer check executions in progress. This method is used when stopping the Sensu client. The `retry_until_true` helper method is used to check the condition every 0.5 seconds until `true` is returned.

@yield [] callback/block called when there are no check

executions in progress.
# File lib/sensu/client/process.rb, line 338
def complete_checks_in_progress
  @logger.info("completing checks in progress", :checks_in_progress => @checks_in_progress)
  retry_until_true do
    if @checks_in_progress.empty?
      yield
      true
    end
  end
end
execute_check_command(check) click to toggle source

Execute a check command, capturing its output (STDOUT/ERR), exit status code, execution duration, timestamp, and publish the result. This method guards against multiple executions for the same check. Check command tokens are substituted with the associated client attribute values. If there are unmatched check command tokens, the check command will not be executed, instead a check result will be published reporting the unmatched tokens.

@param check [Hash]

# File lib/sensu/client/process.rb, line 112
def execute_check_command(check)
  @logger.debug("attempting to execute check command", :check => check)
  unless @checks_in_progress.include?(check[:name])
    @checks_in_progress << check[:name]
    command, unmatched_tokens = substitute_tokens(check[:command], @settings[:client])
    if unmatched_tokens.empty?
      check[:executed] = Time.now.to_i
      started = Time.now.to_f
      Spawn.process(command, :timeout => check[:timeout]) do |output, status|
        check[:duration] = ("%.3f" % (Time.now.to_f - started)).to_f
        check[:output] = output
        check[:status] = status
        publish_check_result(check)
        @checks_in_progress.delete(check[:name])
      end
    else
      check[:output] = "Unmatched command tokens: " + unmatched_tokens.join(", ")
      check[:status] = 3
      check[:handle] = false
      publish_check_result(check)
      @checks_in_progress.delete(check[:name])
    end
  else
    @logger.warn("previous check command execution in progress", :check => check)
  end
end
keepalive_payload() click to toggle source

Create a Sensu client keepalive payload, to be sent over the transport for processing. A client keepalive is composed of its settings definition, the Sensu version, and a timestamp. Sensitive information is redacted from the keepalive payload.

@return [Hash] keepalive payload

# File lib/sensu/client/process.rb, line 41
def keepalive_payload
  payload = @settings[:client].merge({
    :version => VERSION,
    :timestamp => Time.now.to_i
  })
  redact_sensitive(payload, @settings[:client][:redact])
end
pause() click to toggle source

Pause the Sensu client process, unless it is being paused or has already been paused. The process/daemon `@state` is first set to `:pausing`, to indicate that it's in progress. All run timers are cancelled, and the references are cleared. The Sensu client will unsubscribe from all transport subscriptions, then set the process/daemon `@state` to `:paused`.

# File lib/sensu/client/process.rb, line 392
def pause
  unless @state == :pausing || @state == :paused
    @state = :pausing
    @timers[:run].each do |timer|
      timer.cancel
    end
    @timers[:run].clear
    @transport.unsubscribe if @transport
    @state = :paused
  end
end
process_check_request(check) click to toggle source

Process a check request. If a check request has a check command, it will be executed. A standard check request will be merged with a local check definition, if present. Client safe mode is enforced in this method, requiring a local check definition in order to execute the check command. If a local check definition does not exist when operating with client safe mode, a check result will be published to report the missing check definition. A check request without a command indicates a check extension run. The check request may contain `:extension`, the name of the extension to run. If `:extension` is not present, the check name is used for the extension name. If a check extension does not exist for a name, a check result will be published to report the unknown check extension.

@param check [Hash]

# File lib/sensu/client/process.rb, line 178
def process_check_request(check)
  @logger.debug("processing check", :check => check)
  if @settings.check_exists?(check[:name])
    check.merge!(@settings[:checks][check[:name]])
  end
  if check.has_key?(:command)
    if @safe_mode && !@settings.check_exists?(check[:name])
      check[:output] = "Check is not locally defined (safe mode)"
      check[:status] = 3
      check[:handle] = false
      check[:executed] = Time.now.to_i
      publish_check_result(check)
    else
      execute_check_command(check)
    end
  else
    extension_name = check[:extension] || check[:name]
    if @extensions.check_exists?(extension_name)
      run_check_extension(check)
    else
      @logger.warn("unknown check extension", :check => check)
    end
  end
end
publish_check_result(check) click to toggle source

Publish a check result to the transport for processing. A check result is composed of a client (name) and a check definition, containing check `:output` and `:status`. JSON serialization is used when publishing the check result payload to the transport pipe. The check result is signed with the client signature if configured, for source validation. Transport errors are logged.

@param check [Hash]

# File lib/sensu/client/process.rb, line 85
def publish_check_result(check)
  payload = {
    :client => @settings[:client][:name],
    :check => check
  }
  payload[:signature] = @settings[:client][:signature] if @settings[:client][:signature]
  @logger.info("publishing check result", :payload => payload)
  @transport.publish(:direct, "results", Sensu::JSON.dump(payload)) do |info|
    if info[:error]
      @logger.error("failed to publish check result", {
        :payload => payload,
        :error => info[:error].to_s
      })
    end
  end
end
publish_keepalive() click to toggle source

Publish a Sensu client keepalive to the transport for processing. JSON serialization is used for transport messages.

# File lib/sensu/client/process.rb, line 51
def publish_keepalive
  payload = keepalive_payload
  @logger.debug("publishing keepalive", :payload => payload)
  @transport.publish(:direct, "keepalives", Sensu::JSON.dump(payload)) do |info|
    if info[:error]
      @logger.error("failed to publish keepalive", {
        :payload => payload,
        :error => info[:error].to_s
      })
    end
  end
end
resume() click to toggle source

Resume the Sensu client process if it is currently or will soon be paused. The `retry_until_true` helper method is used to determine if the process is paused and if the transport is connected. If the conditions are met, `bootstrap()` will be called and true is returned to stop `retry_until_true`.

# File lib/sensu/client/process.rb, line 409
def resume
  retry_until_true(1) do
    if @state == :paused
      if @transport.connected?
        bootstrap
        true
      end
    end
  end
end
run_check_extension(check) click to toggle source

Run a check extension and publish the result. The Sensu client loads check extensions, checks that run within the Sensu Ruby VM and the EventMachine event loop, using the Sensu Extension API. If a check definition includes `:extension`, use it's value for the extension name, otherwise use the check name. The check definition is passed to the extension `safe_run()` method as a parameter, the extension may utilize it.

github.com/sensu/sensu-extension

@param check [Hash]

# File lib/sensu/client/process.rb, line 150
def run_check_extension(check)
  @logger.debug("attempting to run check extension", :check => check)
  check[:executed] = Time.now.to_i
  extension_name = check[:extension] || check[:name]
  extension = @extensions[:checks][extension_name]
  extension.safe_run(check) do |output, status|
    check[:output] = output
    check[:status] = status
    publish_check_result(check)
  end
end
schedule_checks(checks) click to toggle source

Schedule check executions, using EventMachine periodic timers, using a calculated execution splay. The timers are stored in the timers hash under `:run`, so they can be cancelled etc. Check definitions are duplicated before processing them, in case they are mutated. The check `:issued` timestamp is set here, to mimic check requests issued by a Sensu server.

@param checks [Array] of definitions.

# File lib/sensu/client/process.rb, line 273
def schedule_checks(checks)
  checks.each do |check|
    execute_check = Proc.new do
      check[:issued] = Time.now.to_i
      process_check_request(check.dup)
    end
    execution_splay = testing? ? 0 : calculate_execution_splay(check)
    interval = testing? ? 0.5 : check[:interval]
    @timers[:run] << EM::Timer.new(execution_splay) do
      execute_check.call
      @timers[:run] << EM::PeriodicTimer.new(interval, &execute_check)
    end
  end
end
setup_keepalives() click to toggle source

Schedule Sensu client keepalives. Immediately publish a keepalive to register the client, then publish a keepalive every 20 seconds. Sensu client keepalives are used to determine client (& machine) health.

# File lib/sensu/client/process.rb, line 68
def setup_keepalives
  @logger.debug("scheduling keepalives")
  publish_keepalive
  @timers[:run] << EM::PeriodicTimer.new(20) do
    publish_keepalive
  end
end
setup_sockets() click to toggle source

Setup the Sensu client socket, for external check result input. By default, the client socket is bound to localhost on TCP & UDP port 3030. The socket can be configured via the client definition, `:socket` with `:bind` and `:port`. The current instance of the Sensu logger, settings, and transport are passed to the socket handler, `Sensu::Client::Socket`. The TCP socket server signature (Fixnum) and UDP connection object are stored in `@sockets`, so that they can be managed elsewhere, eg. `close_sockets()`.

# File lib/sensu/client/process.rb, line 312
def setup_sockets
  options = @settings[:client][:socket] || Hash.new
  options[:bind] ||= "127.0.0.1"
  options[:port] ||= 3030
  @logger.debug("binding client tcp and udp sockets", :options => options)
  @sockets << EM::start_server(options[:bind], options[:port], Socket) do |socket|
    socket.logger = @logger
    socket.settings = @settings
    socket.transport = @transport
  end
  @sockets << EM::open_datagram_socket(options[:bind], options[:port], Socket) do |socket|
    socket.logger = @logger
    socket.settings = @settings
    socket.transport = @transport
    socket.protocol = :udp
  end
end
setup_standalone() click to toggle source

Setup standalone check executions, scheduling standard check definition and check extension executions. Check definitions and extensions with `:standalone` set to `true` will be scheduled by the Sensu client for execution.

# File lib/sensu/client/process.rb, line 292
def setup_standalone
  @logger.debug("scheduling standalone checks")
  standard_checks = @settings.checks.select do |check|
    check[:standalone]
  end
  extension_checks = @extensions.checks.select do |check|
    check[:standalone] && check[:interval].is_a?(Integer)
  end
  schedule_checks(standard_checks + extension_checks)
end
setup_subscriptions() click to toggle source

Set up Sensu client subscriptions. Subscriptions determine the kinds of check requests the client will receive. The Sensu client will receive JSON serialized check requests from its subscriptions, that get parsed and processed.

# File lib/sensu/client/process.rb, line 233
def setup_subscriptions
  @logger.debug("subscribing to client subscriptions")
  @settings[:client][:subscriptions].each do |subscription|
    @logger.debug("subscribing to a subscription", :subscription => subscription)
    options = transport_subscribe_options(subscription)
    @transport.subscribe(*options) do |message_info, message|
      begin
        check = Sensu::JSON.load(message)
        @logger.info("received check request", :check => check)
        process_check_request(check)
      rescue Sensu::JSON::ParseError => error
        @logger.error("failed to parse the check request payload", {
          :message => message,
          :error => error.to_s
        })
      end
    end
  end
end
start() click to toggle source

Start the Sensu client process, setting up the client transport connection, the sockets, and calling the `bootstrap()` method.

# File lib/sensu/client/process.rb, line 378
def start
  setup_transport do
    setup_sockets
    bootstrap
  end
end
stop() click to toggle source

Stop the Sensu client process, pausing it, completing check executions in progress, closing the transport connection, and exiting the process (exit 0). After pausing the process, the process/daemon `@state` is set to `:stopping`.

Calls superclass method Sensu::Daemon#stop
# File lib/sensu/client/process.rb, line 424
def stop
  @logger.warn("stopping")
  pause
  @state = :stopping
  complete_checks_in_progress do
    close_sockets
    @transport.close if @transport
    super
  end
end
transport_subscribe_options(subscription) click to toggle source

Determine the Sensu transport subscribe options for a subscription. If a subscription begins with a transport pipe type, either “direct:” or “roundrobin:”, the subscription uses a direct transport pipe, and the subscription name is used for both the pipe and the funnel names. If a subscription does not specify a transport pipe type, a fanout transport pipe is used, the subscription name is used for the pipe, and a unique funnel is created for the Sensu client. The unique funnel name for the Sensu client is created using a combination of the client name, the Sensu version, and the process start time (epoch).

@param subscription [String] @return [Array] containing the transport subscribe options:

the transport pipe type, pipe, and funnel.
# File lib/sensu/client/process.rb, line 218
def transport_subscribe_options(subscription)
  _, raw_type = subscription.split(":", 2).reverse
  case raw_type
  when "direct", "roundrobin"
    [:direct, subscription, subscription]
  else
    funnel = [@settings[:client][:name], VERSION, start_time].join("-")
    [:fanout, subscription, funnel]
  end
end