Class: Sensu::Client::Process

Inherits:
Object
  • Object
show all
Includes:
Daemon
Defined in:
lib/sensu/client/process.rb

Instance Attribute Summary collapse

Attributes included from Daemon

#settings, #start_time

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Daemon

#load_extensions, #load_settings, #log_notices, #print_settings!, #setup_logger, #setup_process, #setup_redis, #setup_signal_traps, #setup_spawn, #setup_transport, #validate_settings!

Methods included from Utilities

#check_subdued?, #deep_merge, #find_attribute_value, #in_time_window?, #in_time_windows?, #random_uuid, #redact_sensitive, #retry_until_true, #substitute_tokens, #testing?

Constructor Details

#initialize(options = {}) ⇒ Process

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

Parameters:

  • options (Hash) (defaults to: {}) 


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# File 'lib/sensu/client/process.rb', line 29

def initialize(options={})
  super
  @safe_mode = @settings[:client][:safe_mode] || false
  @checks_in_progress = []
  @sockets = []
end

Instance Attribute Details

#safe_mode ⇒ Object

Returns the value of attribute safe_mode.



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# File 'lib/sensu/client/process.rb', line 10

def safe_mode
  @safe_mode
end

Class Method Details

.run(options = {}) ⇒ Object

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).

Parameters:

  • options (Hash) (defaults to: {}) 


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# File 'lib/sensu/client/process.rb', line 17

def self.run(options={})
  client = self.new(options)
  EM::run do
    client.start
    client.setup_signal_traps
  end
end

Instance Method Details

#bootstrap ⇒ Object

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



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# File 'lib/sensu/client/process.rb', line 470

def bootstrap
  setup_keepalives
  setup_subscriptions
  setup_standalone
  @state = :running
end

#calculate_execution_splay(check) ⇒ Object

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

Parameters:

  • check (Hash) —

    definition.



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# File 'lib/sensu/client/process.rb', line 300

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 ⇒ Object

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.



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# File 'lib/sensu/client/process.rb', line 456

def close_sockets
  @logger.info("closing client 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 { ... } ⇒ Object

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.

Yields:

  • callback/block called when there are no check

    executions in progress.



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# File 'lib/sensu/client/process.rb', line 417

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

#deregister ⇒ Object

Create a check result intended for deregistering a client. Client definitions may contain ‘:deregistration` configuration, containing custom attributes and handler information. By default, the deregistration check result sets the `:handler` to `deregistration`. If the client provides its own `:deregistration` configuration, it’s deep merged with the defaults. The check ‘:name`, `:output`, `:issued`, and `:executed` values are always overridden to guard against an invalid definition.



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# File 'lib/sensu/client/process.rb', line 435

def deregister
  check = {:handler => "deregistration", :status => 1}
  if @settings[:client].has_key?(:deregistration)
    check = deep_merge(check, @settings[:client][:deregistration])
  end
  timestamp = Time.now.to_i
  overrides = {
    :name => "deregistration",
    :output => "client initiated deregistration",
    :issued => timestamp,
    :executed => timestamp
  }
  publish_check_result(check.merge(overrides))
end

#execute_check_command(check) ⇒ Object

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 attribute value tokens are substituted with the associated client attribute values, via ‘object_substitute_tokens()`. The original check command is always published, to guard against publishing sensitive/redacted client attribute values. If there are unmatched check attribute value tokens, the check will not be executed, instead a check result will be published reporting the unmatched tokens.

Parameters:

  • check (Hash) 


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# File 'lib/sensu/client/process.rb', line 143

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]
    substituted, unmatched_tokens = object_substitute_tokens(check.dup)
    check = substituted.merge(:command => check[:command])
    started = Time.now.to_f
    check[:executed] = started.to_i
    if unmatched_tokens.empty?
      Spawn.process(substituted[: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 client token(s): " + 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 ⇒ Hash

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.

Returns:

  • (Hash) —

    keepalive payload



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# File 'lib/sensu/client/process.rb', line 42

def keepalive_payload
  payload = @settings[:client].merge({
    :version => VERSION,
    :timestamp => Time.now.to_i
  })
  redact_sensitive(payload, @settings[:client][:redact])
end

#object_substitute_tokens(object) ⇒ Array

Perform token substitution for an object. String values are passed to ‘substitute_tokens()`, arrays and sub-hashes are processed recursively. Numeric values are ignored.

Parameters:

  • object (Object)

Returns:

  • (Array) —

    containing the updated object with substituted values and an array of unmatched tokens.



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# File 'lib/sensu/client/process.rb', line 110

def object_substitute_tokens(object)
  unmatched_tokens = []
  case object
  when Hash
    object.each do |key, value|
      object[key], unmatched = object_substitute_tokens(value)
      unmatched_tokens.push(*unmatched)
    end
  when Array
    object.map! do |value|
      value, unmatched = object_substitute_tokens(value)
      unmatched_tokens.push(*unmatched)
      value
    end
  when String
    object, unmatched_tokens = substitute_tokens(object, @settings[:client])
  end
  [object, unmatched_tokens.uniq]
end

#pause ⇒ Object

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`.



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# File 'lib/sensu/client/process.rb', line 494

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) ⇒ Object

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.

Parameters:

  • check (Hash) 


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# File 'lib/sensu/client/process.rb', line 220

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) ⇒ Object

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.

Parameters:

  • check (Hash) 


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# File 'lib/sensu/client/process.rb', line 86

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 ⇒ Object

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



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# File 'lib/sensu/client/process.rb', line 52

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 ⇒ Object

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`.



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# File 'lib/sensu/client/process.rb', line 511

def resume
  retry_until_true(1) do
    if @state == :paused
      if @transport.connected?
        bootstrap
        true
      end
    end
  end
end

#run_check_extension(check) ⇒ Object

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. This method guards against multiple executions for the same check extension.

github.com/sensu/sensu-extension

Parameters:

  • check (Hash) 


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# File 'lib/sensu/client/process.rb', line 184

def run_check_extension(check)
  @logger.debug("attempting to run check extension", :check => check)
  unless @checks_in_progress.include?(check[:name])
    @checks_in_progress << check[:name]
    started = Time.now.to_f
    check[:executed] = started.to_i
    extension_name = check[:extension] || check[:name]
    extension = @extensions[:checks][extension_name]
    extension.safe_run(check) 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
    @logger.warn("previous check extension execution in progress", :check => check)
  end
end

#schedule_checks(checks) ⇒ Object

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. A check will not be executed if it is subdued. The check `:issued` timestamp is set here, to mimic check requests issued by a Sensu server.

Parameters:

  • checks (Array) —

    of definitions.



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# File 'lib/sensu/client/process.rb', line 316

def schedule_checks(checks)
  checks.each do |check|
    execute_check = Proc.new do
      unless check_subdued?(check)
        check[:issued] = Time.now.to_i
        process_check_request(check.dup)
      else
        @logger.info("check execution was subdued", :check => check)
      end
    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_http_socket ⇒ Object

Setup the Sensu client HTTP socket, for external check result input and informational queries. By default, the client HTTP socket is bound to localhost on TCP port 3031. The socket can be configured via the client definition, ‘:http_socket` with `:bind` and `:port`. Users can opt-out of using the HTTP socket by setting `:enabled` to `false. The current instance of the Sensu logger, settings, and transport are passed to the HTTP socket handler, `Sensu::Client::HTTPSocket`. The HTTP socket server signature (Fixnum) is stored in `@sockets`, so that it can be managed elsewhere, eg. `close_sockets()`.



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# File 'lib/sensu/client/process.rb', line 388

def setup_http_socket
  options = @settings[:client][:http_socket] || Hash.new
  options[:bind] ||= "127.0.0.1"
  options[:port] ||= 3031
  unless options[:enabled] == false
    @logger.debug("binding client http socket", :options => options)
    @sockets << EM::start_server(options[:bind], options[:port], HTTPSocket) do |socket|
      socket.logger = @logger
      socket.settings = @settings
      socket.transport = @transport
    end
  end
end

#setup_json_socket ⇒ Object

Setup the Sensu client JSON 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()`.



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# File 'lib/sensu/client/process.rb', line 360

def setup_json_socket
  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_keepalives ⇒ Object

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.



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# File 'lib/sensu/client/process.rb', line 69

def setup_keepalives
  @logger.debug("scheduling keepalives")
  publish_keepalive
  @timers[:run] << EM::PeriodicTimer.new(20) do
    publish_keepalive
  end
end

#setup_sockets ⇒ Object

Setup the Sensu client sockets, JSON TCP & UDP, and HTTP. Users can opt-out of using the HTTP socket via configuration.



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# File 'lib/sensu/client/process.rb', line 404

def setup_sockets
  setup_json_socket
  setup_http_socket
end

#setup_standalone ⇒ Object

Setup standalone check executions, scheduling standard check definition and check extension executions. Check definitions and extensions with ‘:standalone` set to `true`, have a integer `:interval`, and do not have `:publish` set to `false` will be scheduled by the Sensu client for execution.



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# File 'lib/sensu/client/process.rb', line 340

def setup_standalone
  @logger.debug("scheduling standalone checks")
  standard_checks = @settings.checks.select do |check|
    check[:standalone] && check[:interval].is_a?(Integer) && check[:publish] != false
  end
  extension_checks = @extensions.checks.select do |check|
    check[:standalone] && check[:interval].is_a?(Integer) && check[:publish] != false
  end
  schedule_checks(standard_checks + extension_checks)
end

#setup_subscriptions ⇒ Object

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.



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# File 'lib/sensu/client/process.rb', line 275

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 ⇒ Object

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



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# File 'lib/sensu/client/process.rb', line 480

def start
  setup_transport do
    setup_sockets
    bootstrap
  end
end

#stop ⇒ Object

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`. Also sends deregistration check result if configured to do so.



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# File 'lib/sensu/client/process.rb', line 527

def stop
  @logger.warn("stopping")
  last_state = @state
  pause
  if @settings[:client][:deregister] == true && last_state != :initializing
    deregister
  end
  @state = :stopping
  complete_checks_in_progress do
    close_sockets
    @transport.close if @transport
    super
  end
end

#transport_subscribe_options(subscription) ⇒ Array

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).

Parameters:

  • subscription (String)

Returns:

  • (Array) —

    containing the transport subscribe options: the transport pipe type, pipe, and funnel.



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# File 'lib/sensu/client/process.rb', line 260

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