Class: Sensu::Server::Process

Inherits:
Object
  • Object
show all
Includes:
Daemon, Filter, Handle, Mutate
Defined in:
lib/sensu/server/process.rb

Constant Summary collapse

STANDARD_CHECK_TYPE = 
"standard".freeze
METRIC_CHECK_TYPE = 
"metric".freeze
EVENT_FLAPPING_ACTION = 
"flapping".freeze
DEFAULT_HANDLER_NAME = 
"default".freeze

Constants included from Filter

Filter::EVAL_PREFIX

Instance Attribute Summary collapse

Attributes included from Daemon

#settings, #start_time

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Handle

#handle_event, #handler_error, #handler_extension, #handler_type_router, #pipe_handler, #tcp_handler, #transport_handler, #udp_handler

Methods included from Mutate

#mutate_event, #mutator_callback, #mutator_extension, #pipe_mutator

Methods included from Filter

#eval_attribute_value, #event_filter, #event_filtered?, #extension_filter, #filter_attributes_match?, #filter_event, #handle_action?, #handle_severity?, #handler_silenced?, #handling_disabled?, #in_filter_time_windows?, #native_filter, #process_eval_string

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 server leader election and the handling event count.

Parameters:

  • options (Hash) (defaults to: {}) 


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# File 'lib/sensu/server/process.rb', line 41

def initialize(options={})
  super
  @is_leader = false
  @timers[:leader] = Array.new
  @in_progress = Hash.new(0)
end

Instance Attribute Details

#in_progress ⇒ Object (readonly)

Returns the value of attribute in_progress.



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# File 'lib/sensu/server/process.rb', line 14

def in_progress
  @in_progress
end

#is_leader ⇒ Object (readonly)

Returns the value of attribute is_leader.



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# File 'lib/sensu/server/process.rb', line 14

def is_leader
  @is_leader
end

Class Method Details

.run(options = {}) ⇒ Object

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

Parameters:

  • options (Hash) (defaults to: {}) 


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

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

Instance Method Details

#aggregate_check_result(client, check) ⇒ Object

Add a check result to one or more aggregates. The aggregate name is determined by the value of check ‘:aggregates` array, if present, and falling back to `:aggregate` otherwise.

When one or more aggregates are specified as ‘:aggregates`, the client name and check are updated on each aggregate.

When no aggregates are specified as ‘:aggregates`, and `:aggregate` is `true` (legacy), the check `:name` is used as the aggregate name.

When no aggregates are specified as ‘:aggregates` and check `:aggregate` is a string, it used as the aggregate name.

This method will add the client name to configured aggregates, all other processing (e.g. counters) is done by the Sensu API on request.

Parameters:

  • client (Hash)
  • check (Hash) 


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# File 'lib/sensu/server/process.rb', line 295

def aggregate_check_result(client, check)
  check_aggregate = (check[:aggregate].is_a?(String) ? check[:aggregate] : check[:name])
  aggregate_list = Array(check[:aggregates] || check_aggregate)
  aggregate_list.each do |aggregate|
    @logger.debug("adding check result to aggregate", {
      :aggregate => aggregate,
      :client => client,
      :check => check
    })
    aggregate_member = "#{client[:name]}:#{check[:name]}"
    @redis.sadd("aggregates:#{aggregate}", aggregate_member) do
      @redis.sadd("aggregates", aggregate)
    end
  end
end

#become_the_leader ⇒ Object

Become the Sensu server leader, responsible for specific duties (‘leader_duties()`). Unless the current process is already the leader, this method sets the leader ID stored in Redis to the unique random leader ID for the process. If the leader ID in Redis is successfully updated, `@is_leader` is set to true and `leader_duties()` is called to begin the tasks/duties of the Sensu server leader.



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# File 'lib/sensu/server/process.rb', line 1029

def become_the_leader
  unless @is_leader
    @redis.set("leader", leader_id) do
      @logger.info("i am now the leader")
      @is_leader = true
      leader_duties
    end
  else
    @logger.debug("i am already the leader")
  end
end

#bootstrap ⇒ Object

Bootstrap the Sensu server process, setting up the keepalive and check result consumers, and attemping to become the leader to carry out its duties. This method sets the process/daemon ‘@state` to `:running`.



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# File 'lib/sensu/server/process.rb', line 1161

def bootstrap
  setup_keepalives
  setup_results
  setup_leader_monitor
  @state = :running
end

#calculate_check_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/server/process.rb', line 767

def calculate_check_execution_splay(check)
  splay_hash = Digest::MD5.digest(check[:name]).unpack('Q<').first
  current_time = (Time.now.to_f * 1000).to_i
  (splay_hash - current_time) % (check[:interval] * 1000) / 1000.0
end

#check_flapping?(stored_event, check) ⇒ TrueClass, FalseClass

Determine if a check state is flapping, rapidly changing between an OK and non-OK state. Flap detection is only done for checks that have defined low and hight flap detection thresholds, ‘:low_flap_threshold` and `:high_flap_threshold`. The `check_history()` method provides the check history and more importantly the total state change precentage value that is compared with the configured thresholds defined in the check data. If a check hasn’t been flapping, the ‘:total_state_change` must be equal to or higher than the `:high_flap_threshold` to be changed to flapping. If a check has been flapping, the `:total_state_change` must be equal to or lower than the `:low_flap_threshold` to no longer be flapping. This method uses the same algorithm as Nagios: nagios.sourceforge.net/docs/3_0/flapping.html

Parameters:

  • stored_event (Hash)
  • check (Hash)

Returns:

  • (TrueClass, FalseClass) 


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# File 'lib/sensu/server/process.rb', line 423

def check_flapping?(stored_event, check)
  if check.has_key?(:low_flap_threshold) && check.has_key?(:high_flap_threshold)
    was_flapping = stored_event && stored_event[:action] == EVENT_FLAPPING_ACTION
    if was_flapping
      check[:total_state_change] > check[:low_flap_threshold]
    else
      check[:total_state_change] >= check[:high_flap_threshold]
    end
  else
    false
  end
end

#check_history(client, check) {|history, total_state_change| ... } ⇒ Object

Fetch the execution history for a client/check pair, the 21 most recent check result statuses. This method also calculates the total state change percentage for the history, this value is use for check state flap detection, using a similar algorithm to Nagios: nagios.sourceforge.net/docs/3_0/flapping.html

Parameters:

  • client (Hash)
  • check (Hash)

Yields:

  • (history, total_state_change) —

    callback/block to call with the check history and calculated total state change value.

Yield Parameters:

  • history (Array) —

    containing the last 21 check result exit status codes.

  • total_state_change (Float) —

    percentage for the check history (exit status codes).



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# File 'lib/sensu/server/process.rb', line 384

def check_history(client, check)
  history_key = "history:#{client[:name]}:#{check[:name]}"
  @redis.lrange(history_key, -21, -1) do |history|
    total_state_change = 0
    unless history.length < 21
      state_changes = 0
      change_weight = 0.8
      previous_status = history.first
      history.each do |status|
        unless status == previous_status
          state_changes += change_weight
        end
        change_weight += 0.02
        previous_status = status
      end
      total_state_change = (state_changes.fdiv(20) * 100).to_i
    end
    yield(history, total_state_change)
  end
end

#complete_in_progress { ... } ⇒ Object

Complete in progress work and then call the provided callback. This method will wait until all counters stored in the ‘@in_progress` hash equal `0`.

Yields:

  • callback/block to call when in progress work is

    completed.



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# File 'lib/sensu/server/process.rb', line 1147

def complete_in_progress
  @logger.info("completing work in progress", :in_progress => @in_progress)
  retry_until_true do
    if @in_progress.values.all? { |count| count == 0 }
      yield
      true
    end
  end
end

#create_client(name) ⇒ Hash

Create a blank client (data). Only the client name is known, the other client attributes must be updated via the API (POST /clients:client). Dynamically created clients and those updated via the API will have client keepalives disabled by default, ‘:keepalives` is set to `false`.

Parameters:

  • name (String) —

    to use for the client.

Returns:

  • (Hash) —

    client.



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# File 'lib/sensu/server/process.rb', line 581

def create_client(name)
  {
    :name => name,
    :address => "unknown",
    :subscriptions => ["client:#{name}"],
    :keepalives => false,
    :version => VERSION
  }
end

#create_client_keepalive_check_results(clients) { ... } ⇒ Object

Create client keepalive check results. This method will retrieve clients from the registry, creating a keepalive check definition for each client, using the ‘create_keepalive_check()` method, containing client specific keepalive thresholds. If the time since the latest keepalive is equal to or greater than a threshold, the check `:output` is set to a descriptive message, and `:status` is set to the appropriate non-zero value. If a client has been sending keepalives, `:output` and `:status` are set to indicate an OK state. The `publish_check_result()` method is used to publish the client keepalive check results.

Parameters:

  • clients (Array) —

    of client names.

Yields:

  • callback/block called after the client keepalive

    check results have been created.



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# File 'lib/sensu/server/process.rb', line 885

def create_client_keepalive_check_results(clients)
  client_keys = clients.map { |client_name| "client:#{client_name}" }
  @redis.mget(*client_keys) do |client_json_objects|
    client_json_objects.each do |client_json|
      unless client_json.nil?
        client = Sensu::JSON.load(client_json)
        next if client[:keepalives] == false
        check = create_keepalive_check(client)
        time_since_last_keepalive = Time.now.to_i - client[:timestamp]
        check[:output] = "No keepalive sent from client for "
        check[:output] << "#{time_since_last_keepalive} seconds"
        case
        when time_since_last_keepalive >= check[:thresholds][:critical]
          check[:output] << " (>=#{check[:thresholds][:critical]})"
          check[:status] = 2
        when time_since_last_keepalive >= check[:thresholds][:warning]
          check[:output] << " (>=#{check[:thresholds][:warning]})"
          check[:status] = 1
        else
          check[:output] = "Keepalive sent from client "
          check[:output] << "#{time_since_last_keepalive} seconds ago"
          check[:status] = 0
        end
        publish_check_result(client[:name], check)
      end
    end
    yield
  end
end

#create_client_registration_event(client) ⇒ Object

Create and process a client registration event. A registration event is created when a Sensu client is first added to the client registry. The ‘create_registration_check()` method is called to create a registration check definition for the client.

Parameters:

  • client (Hash) —

    definition.



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# File 'lib/sensu/server/process.rb', line 99

def create_client_registration_event(client)
  check = create_registration_check(client)
  create_event(client, check) do |event|
    event_bridges(event)
    process_event(event)
  end
end

#create_event(client, check) {|event| ... } ⇒ Object

Create an event, using the provided client and check result data. Existing event data for the client/check pair is fetched from the event registry to be used in the composition of the new event. The silenced registry is used to determine if the event has been silenced.

Parameters:

  • client (Hash)
  • check (Hash)

Yield Parameters:

  • event (Hash) 


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# File 'lib/sensu/server/process.rb', line 524

def create_event(client, check)
  check_history(client, check) do |history, total_state_change|
    check[:history] = history
    check[:total_state_change] = total_state_change
    @redis.hget("events:#{client[:name]}", check[:name]) do |event_json|
      stored_event = event_json ? Sensu::JSON.load(event_json) : nil
      flapping = check_flapping?(stored_event, check)
      event = {
        :client => client,
        :check => check,
        :occurrences => 1,
        :occurrences_watermark => 1,
        :action => (flapping ? :flapping : :create),
        :timestamp => Time.now.to_i
      }
      if stored_event
        event[:id] = stored_event[:id]
        event[:last_state_change] = stored_event[:last_state_change]
        event[:last_ok] = stored_event[:last_ok]
        event[:occurrences] = stored_event[:occurrences]
        event[:occurrences_watermark] = stored_event[:occurrences_watermark] || event[:occurrences]
      else
        event[:id] = random_uuid
        event[:last_ok] = event[:timestamp]
      end
      if check[:status] != 0 || flapping
        if history[-1] == history[-2]
          event[:occurrences] += 1
          if event[:occurrences] > event[:occurrences_watermark]
            event[:occurrences_watermark] = event[:occurrences]
          end
        else
          event[:occurrences] = 1
          event[:last_state_change] = event[:timestamp]
        end
      elsif stored_event
        event[:last_state_change] = event[:timestamp]
        event[:action] = :resolve
      end
      if check[:status] == 0
        event[:last_ok] = event[:timestamp]
      end
      event_silenced?(event) do |event|
        yield(event)
      end
    end
  end
end

#create_keepalive_check(client) ⇒ Object

Create a keepalive check definition for a client. Client definitions may contain ‘:keepalive` configuration, containing specific thresholds and handler information. The keepalive check definition creation begins with default thresholds, and sets the `:handler` to `keepalive`, if the handler has a local definition. If the client provides its own `:keepalive` configuration, it’s deep merged with the defaults. The check ‘:name`, `:issued`, and `:executed` values are always overridden to guard against an invalid definition.



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# File 'lib/sensu/server/process.rb', line 853

def create_keepalive_check(client)
  check = {
    :thresholds => {
      :warning => 120,
      :critical => 180
    }
  }
  if @settings.handler_exists?(:keepalive)
    check[:handler] = "keepalive"
  end
  if client.has_key?(:keepalive)
    check = deep_merge(check, client[:keepalive])
  end
  timestamp = Time.now.to_i
  check.merge(:name => "keepalive", :issued => timestamp, :executed => timestamp)
end

#create_lock_timestamp ⇒ Integer

Create a lock timestamp (integer), current time including milliseconds. This method is used by Sensu server leader election.

Returns:

  • (Integer) 


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# File 'lib/sensu/server/process.rb', line 1010

def create_lock_timestamp
  (Time.now.to_f * 1000).to_i
end

#create_registration_check(client) ⇒ Object

Create a registration check definition for a client. Client definitions may contain ‘:registration` configuration, containing custom attributes and handler information. By default, the registration check definition sets the `:handler` to `registration`. If the client provides its own `:registration` 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/server/process.rb', line 77

def create_registration_check(client)
  check = {:handler => "registration", :status => 1}
  if client.has_key?(:registration)
    check = deep_merge(check, client[:registration])
  end
  timestamp = Time.now.to_i
  overrides = {
    :name => "registration",
    :output => "new client registration",
    :issued => timestamp,
    :executed => timestamp
  }
  check.merge(overrides)
end

#derive_handlers(handler_list, depth = 0) ⇒ Array

Derive an array of handler definitions from a list of handler names. This method first checks for the existence of standard handlers, followed by handler extensions. If a handler does not exist for a name, it is logged and ignored. Duplicate handler definitions are removed.

Parameters:

  • handler_list (Array)
  • depth (Integer) (defaults to: 0) —

    of handler set expansion.

Returns:

  • (Array) 


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# File 'lib/sensu/server/process.rb', line 222

def derive_handlers(handler_list, depth=0)
  handler_list.compact.map { |handler_name|
    case
    when @settings.handler_exists?(handler_name)
      handler = @settings[:handlers][handler_name].merge(:name => handler_name)
      expand_handler_sets(handler, depth)
    when @extensions.handler_exists?(handler_name)
      @extensions[:handlers][handler_name]
    else
      @logger.error("unknown handler", :handler_name => handler_name)
      nil
    end
  }.flatten.compact.uniq
end

#determine_stale_check_results(interval = 30) ⇒ Object

Determine stale check results, those that have not executed in a specified amount of time (check TTL). This method iterates through stored check results that have a defined TTL value (in seconds). The time since last check execution (in seconds) is calculated for each check result. If the time since last execution is equal to or greater than the check TTL, a warning check result is published with the appropriate check output.



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# File 'lib/sensu/server/process.rb', line 956

def determine_stale_check_results(interval = 30)
  @logger.info("determining stale check results")
  @redis.smembers("ttl") do |result_keys|
    result_keys.each do |result_key|
      @redis.get("result:#{result_key}") do |result_json|
        unless result_json.nil?
          check = Sensu::JSON.load(result_json)
          next unless check[:ttl] && check[:executed] && !check[:force_resolve]
          time_since_last_execution = Time.now.to_i - check[:executed]
          if time_since_last_execution >= check[:ttl]
            client_name = result_key.split(":").first
            keepalive_event_exists?(client_name) do |event_exists|
              unless event_exists
                check[:output] = "Last check execution was "
                check[:output] << "#{time_since_last_execution} seconds ago"
                check[:status] = check[:ttl_status] || 1
                check[:interval] = interval
                publish_check_result(client_name, check)
              end
            end
          end
        else
          @redis.srem("ttl", result_key)
        end
      end
    end
  end
end

#determine_stale_clients ⇒ Object

Determine stale clients, those that have not sent a keepalive in a specified amount of time. This method iterates through the client registry, creating a keepalive check result for each client. The ‘create_client_keepalive_check_results()` method is used to inspect and create keepalive check results for each slice of clients from the registry. A relatively small clients slice size (20) is used to reduce the number of clients inspected within a single tick of the EM reactor.



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# File 'lib/sensu/server/process.rb', line 923

def determine_stale_clients
  @logger.info("determining stale clients")
  @redis.smembers("clients") do |clients|
    client_count = clients.length
    keepalive_check_results = Proc.new do |slice_start, slice_size|
      unless slice_start > client_count - 1
        clients_slice = clients.slice(slice_start..slice_size)
        create_client_keepalive_check_results(clients_slice) do
          keepalive_check_results.call(slice_start + 20, slice_size + 20)
        end
      end
    end
    keepalive_check_results.call(0, 19)
  end
end

#event_bridges(event) ⇒ Object

Run event bridge extensions, within the Sensu EventMachine reactor (event loop). The extension API ‘safe_run()` method is used to guard against most errors. Bridges are for relaying Sensu event data to other services.

Parameters:

  • event (Hash) 


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# File 'lib/sensu/server/process.rb', line 266

def event_bridges(event)
  @extensions[:bridges].each do |name, bridge|
    bridge.safe_run(event) do |output, status|
      @logger.debug("bridge extension output", {
        :extension => bridge.definition,
        :output => output
      })
    end
  end
end

#event_silenced?(event) ⇒ Boolean

Determine if an event has been silenced. This method compiles an array of possible silenced registry entry keys for the event. An attempt is made to fetch one or more of the silenced registry entries to determine if the event has been silenced. The event data is updated to indicate if the event has been silenced. If the event is silenced and the event action is ‘:resolve`, silenced registry entries with `:expire_on_resolve` set to true will be deleted. Silencing is disabled for events with a check status of `0` (OK), unless the event action is `:resolve` or `:flapping`.

Parameters:

  • event (Hash)

Returns:

  • (Boolean) 


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# File 'lib/sensu/server/process.rb', line 450

def event_silenced?(event)
  event[:silenced] = false
  event[:silenced_by] = []
  if event[:check][:status] != 0 || event[:action] != :create
    check_name = event[:check][:name]
    silenced_keys = event[:client][:subscriptions].map { |subscription|
      ["silence:#{subscription}:*", "silence:#{subscription}:#{check_name}"]
    }.flatten
    silenced_keys << "silence:*:#{check_name}"
    @redis.mget(*silenced_keys) do |silenced|
      silenced.compact!
      silenced.each do |silenced_json|
        silenced_info = Sensu::JSON.load(silenced_json)
        if silenced_info[:expire_on_resolve] && event[:action] == :resolve
          silenced_key = "silence:#{silenced_info[:id]}"
          @redis.srem("silenced", silenced_key)
          @redis.del(silenced_key)
        else
          event[:silenced_by] << silenced_info[:id]
        end
      end
      event[:silenced] = !event[:silenced_by].empty?
      yield(event)
    end
  else
    yield(event)
  end
end

#expand_handler_sets(handler, depth = 0) ⇒ Array, ...

Expand event handler sets, creating an array of handler definitions. Handler sets cannot be deeply nested (by choice), this method will return ‘nil` if an attempt is made to deeply nest. If the provided handler definition is not a set, it is returned.

Parameters:

  • handler (Hash) —

    definition.

  • depth (Integer) (defaults to: 0) —

    of the expansion.

Returns:

  • (Array, Hash, Nil) 


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# File 'lib/sensu/server/process.rb', line 200

def expand_handler_sets(handler, depth=0)
  if handler[:type] == "set"
    if depth < 2
      derive_handlers(handler[:handlers], depth + 1)
    else
      @logger.error("handler sets cannot be deeply nested", :handler => handler)
      nil
    end
  else
    handler
  end
end

#keepalive_event_exists?(client_name) ⇒ TrueClass, FalseClass

Determine if a keepalive event exists for a client.

Parameters:

  • client_name (String) —

    name of client to look up in event registry.

Returns:

  • (TrueClass, FalseClass) 


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# File 'lib/sensu/server/process.rb', line 634

def keepalive_event_exists?(client_name)
  @redis.hexists("events:#{client_name}", "keepalive") do |event_exists|
    yield(event_exists)
  end
end

#leader_duties ⇒ Object

Set up the leader duties, tasks only performed by a single Sensu server at a time. The duties include publishing check requests, monitoring for stale clients, and pruning check result aggregations.



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# File 'lib/sensu/server/process.rb', line 999

def leader_duties
  setup_check_request_publisher
  setup_client_monitor
  setup_check_result_monitor
end

#leader_id ⇒ String

Create/return the unique Sensu server leader ID for the current process.

Returns:

  • (String) 


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# File 'lib/sensu/server/process.rb', line 1018

def leader_id
  @leader_id ||= random_uuid
end

#pause ⇒ Object

Pause the Sensu server 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 server will unsubscribe from all transport subscriptions, resign as leader (if currently the leader), then set the process/daemon ‘@state` to `:paused`.



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# File 'lib/sensu/server/process.rb', line 1183

def pause
  unless @state == :pausing || @state == :paused
    @state = :pausing
    @timers[:run].each do |timer|
      timer.cancel
    end
    @timers[:run].clear
    unsubscribe
    resign_as_leader
    @state = :paused
  end
end

#process_check_result(result) ⇒ Object

Process a check result, storing its data, inspecting its contents, and taking the appropriate actions (eg. update the event registry). The ‘@in_progress` counter is incremented by `1` prior to check result processing and then decremented by `1` after updating the event registry. A check result must have a valid client name, associated with a client in the registry or one will be created. If a local check definition exists for the check name, and the check result is not from a standalone check execution, it’s merged with the check result for more context.

Parameters:

  • result (Hash) —

    data.



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# File 'lib/sensu/server/process.rb', line 652

def process_check_result(result)
  @in_progress[:check_results] += 1
  @logger.debug("processing result", :result => result)
  retrieve_client(result) do |client|
    unless client.nil?
      check = case
      when @settings.check_exists?(result[:check][:name]) && !result[:check][:standalone]
        @settings[:checks][result[:check][:name]].merge(result[:check])
      else
        result[:check]
      end
      check[:type] ||= STANDARD_CHECK_TYPE
      check[:origin] = result[:client] if check[:source]
      aggregate_check_result(client, check) if check[:aggregates] || check[:aggregate]
      store_check_result(client, check) do
        create_event(client, check) do |event|
          event_bridges(event)
          update_event_registry(event) do |process|
            process_event(event) if process
            @in_progress[:check_results] -= 1
          end
        end
      end
    else
      @logger.warn("halting result processing", :result => result)
      @in_progress[:check_results] -= 1
    end
  end
end

#process_client_registration(client) ⇒ Object

Process an initial client registration, when it is first added to the client registry. If a registration handler is defined or the client specifies one, a client registration event is created and processed (handled, etc.) for the client (‘create_client_registration_event()`).

Parameters:

  • client (Hash) —

    definition.



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# File 'lib/sensu/server/process.rb', line 114

def process_client_registration(client)
  if @settings.handler_exists?("registration") || client[:registration]
    create_client_registration_event(client)
  end
end

#process_event(event) ⇒ Object

Process an event: filter -> mutate -> handle.

This method determines the appropriate handlers for an event, filtering and mutating the event data for each of them. The ‘@in_progress` counter is incremented by `1`, for each event handler chain (filter -> mutate -> handle).

Parameters:

  • event (Hash) 


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# File 'lib/sensu/server/process.rb', line 245

def process_event(event)
  log_level = event[:check][:type] == METRIC_CHECK_TYPE ? :debug : :info
  @logger.send(log_level, "processing event", :event => event)
  handler_list = Array((event[:check][:handlers] || event[:check][:handler]) || DEFAULT_HANDLER_NAME)
  handlers = derive_handlers(handler_list)
  handlers.each do |handler|
    @in_progress[:events] += 1
    filter_event(handler, event) do |event|
      mutate_event(handler, event) do |event_data|
        handle_event(handler, event_data)
      end
    end
  end
end

#publish_check_request(check) ⇒ Object

Publish a check request to the Transport. A check request is composed of a check definition (minus ‘:subscribers` and `:interval`) and an `:issued` timestamp. The check request is published to a Transport pipe, for each of the check `:subscribers` in its definition, eg. “webserver”. JSON serialization is used when publishing the check request payload to the Transport pipes. Transport errors are logged.

Parameters:

  • check (Hash) —

    definition.



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# File 'lib/sensu/server/process.rb', line 739

def publish_check_request(check)
  payload = check.reject do |key, value|
    [:subscribers, :interval].include?(key)
  end
  payload[:issued] = Time.now.to_i
  @logger.info("publishing check request", {
    :payload => payload,
    :subscribers => check[:subscribers]
  })
  check[:subscribers].each do |subscription|
    options = transport_publish_options(subscription, Sensu::JSON.dump(payload))
    @transport.publish(*options) do |info|
      if info[:error]
        @logger.error("failed to publish check request", {
          :subscription => subscription,
          :payload => payload,
          :error => info[:error].to_s
        })
      end
    end
  end
end

#publish_check_result(client_name, 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`. A client signature is added to the check result payload if one is registered for the client. JSON serialization is used when publishing the check result payload to the Transport pipe. Transport errors are logged.

Parameters:

  • client_name (String)
  • check (Hash) 


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# File 'lib/sensu/server/process.rb', line 825

def publish_check_result(client_name, check)
  payload = {
    :client => client_name,
    :check => check
  }
  @redis.get("client:#{client_name}:signature") do |signature|
    payload[:signature] = signature if signature
    @logger.debug("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
end

#request_leader_election ⇒ Object

Request a leader election, a process to determine if the current process is the Sensu server leader, with its own/unique duties. A Redis key/value is used as a central lock, using the “SETNX” Redis command to set the key/value if it does not exist, using a timestamp for the value. If the current process was able to create the key/value, it is the leader, and must do the duties of the leader. If the current process was not able to create the key/value, but the current timestamp value is equal to or over 30 seconds ago, the “GETSET” Redis command is used to set a new timestamp and fetch the previous value to compare them, to determine if it was set by the current process. If the current process is able to set the timestamp value, it becomes the leader.



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# File 'lib/sensu/server/process.rb', line 1095

def request_leader_election
  @redis.setnx("lock:leader", create_lock_timestamp) do |created|
    if created
      become_the_leader
    else
      @redis.get("lock:leader") do |current_lock_timestamp|
        new_lock_timestamp = create_lock_timestamp
        if new_lock_timestamp - current_lock_timestamp.to_i >= 30000
          @redis.getset("lock:leader", new_lock_timestamp) do |previous_lock_timestamp|
            if previous_lock_timestamp == current_lock_timestamp
              become_the_leader
            end
          end
        end
      end
    end
  end
end

#resign_as_leader ⇒ Object

Resign as leader, if the current process is the Sensu server leader. This method cancels and clears the leader timers, those with references stored in the timers hash under ‘:leader`, and `@is_leader` is set to `false`. The leader ID and leader lock are not removed from Redis, as they will be updated when another server is elected to be the leader, this method does not need to handle Redis connectivity issues.



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# File 'lib/sensu/server/process.rb', line 1048

def resign_as_leader
  if @is_leader
    @logger.warn("resigning as leader")
    @timers[:leader].each do |timer|
      timer.cancel
    end
    @timers[:leader].clear
    @is_leader = false
  else
    @logger.debug("not currently the leader")
  end
end

#resume ⇒ Object

Resume the Sensu server 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 Redis and transport connections are initiated and connected. If the conditions are met, `bootstrap()` will be called and true is returned to stop `retry_until_true`. If the transport has not yet been initiated, true is is returned, without calling bootstrap, as we expect bootstrap will be called after the transport initializes.



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# File 'lib/sensu/server/process.rb', line 1205

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

#retrieve_client(result) {|client| ... } ⇒ Object

Retrieve a client (data) from Redis if it exists. If a client does not already exist, create one (a blank) using the ‘client_key` as the client name. Dynamically create client data can be updated using the API (POST /clients/:client). If a client does exist and it has a client signature, the check result must have a matching signature or it is discarded.

Parameters:

  • result (Hash) —

    data.

Yields:

  • (client) —

    callback/block to be called with client data, either retrieved from Redis, or dynamically created.

Yield Parameters:

  • client (Hash) 


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# File 'lib/sensu/server/process.rb', line 602

def retrieve_client(result)
  client_key = result[:check][:source] || result[:client]
  @redis.get("client:#{client_key}") do |client_json|
    unless client_json.nil?
      client = Sensu::JSON.load(client_json)
      if client[:signature]
        if client[:signature] == result[:signature]
          yield(client)
        else
          @logger.warn("invalid check result signature", {
            :result => result,
            :client => client
          })
          @logger.warn("not retrieving client from the registry", :result => result)
          yield(nil)
        end
      else
        yield(client)
      end
    else
      client = create_client(client_key)
      update_client_registry(client) do
        yield(client)
      end
    end
  end
end

#schedule_check_executions(checks) ⇒ Object

Schedule check executions, using EventMachine periodic timers, using a calculated execution splay. The timers are stored in the timers hash under ‘:leader`, as check request publishing is a task for only the Sensu server leader, so they can be cancelled etc. Check requests are not published if subdued.

Parameters:

  • checks (Array) —

    of definitions.



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# File 'lib/sensu/server/process.rb', line 780

def schedule_check_executions(checks)
  checks.each do |check|
    create_check_request = Proc.new do
      unless check_subdued?(check)
        publish_check_request(check)
      else
        @logger.info("check request was subdued", :check => check)
      end
    end
    execution_splay = testing? ? 0 : calculate_check_execution_splay(check)
    interval = testing? ? 0.5 : check[:interval]
    @timers[:leader] << EM::Timer.new(execution_splay) do
      create_check_request.call
      @timers[:leader] << EM::PeriodicTimer.new(interval, &create_check_request)
    end
  end
end

#setup_check_request_publisher ⇒ Object

Set up the check request publisher. This method creates an array of check definitions, that are not standalone checks, and do not have ‘:publish` set to `false`. The array of check definitions includes those from standard checks and extensions (with a defined execution `:interval`). The array is provided to the `schedule_check_executions()` method.



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# File 'lib/sensu/server/process.rb', line 804

def setup_check_request_publisher
  @logger.debug("scheduling check requests")
  standard_checks = @settings.checks.reject do |check|
    check[:standalone] || check[:publish] == false
  end
  extension_checks = @extensions.checks.reject do |check|
    check[:standalone] || check[:publish] == false || !check[:interval].is_a?(Integer)
  end
  schedule_check_executions(standard_checks + extension_checks)
end

#setup_check_result_monitor(interval = 30) ⇒ Object

Set up the check result monitor, a periodic timer to run ‘determine_stale_check_results()` every 30 seconds. The timer is stored in the timers hash under `:leader`.



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# File 'lib/sensu/server/process.rb', line 988

def setup_check_result_monitor(interval = 30)
  @logger.debug("monitoring check results")
  @timers[:leader] << EM::PeriodicTimer.new(interval) do
    determine_stale_check_results(interval)
  end
end

#setup_client_monitor ⇒ Object

Set up the client monitor, a periodic timer to run ‘determine_stale_clients()` every 30 seconds. The timer is stored in the timers hash under `:leader`.



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# File 'lib/sensu/server/process.rb', line 942

def setup_client_monitor
  @logger.debug("monitoring client keepalives")
  @timers[:leader] << EM::PeriodicTimer.new(30) do
    determine_stale_clients
  end
end

#setup_connections { ... } ⇒ Object

Set up the Redis and Transport connection objects, ‘@redis` and `@transport`. This method updates the Redis on error callback to reset the in progress check result counter. This method “drys” up many instances of `setup_redis()` and `setup_transport()`, particularly in the specs.

Yields:

  • callback/block called after connecting to Redis and the Sensu Transport.



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# File 'lib/sensu/server/process.rb', line 56

def setup_connections
  setup_redis do
    @redis.on_error do |error|
      @logger.error("redis connection error", :error => error.to_s)
      @in_progress[:check_results] = 0
    end
    setup_transport do
      yield
    end
  end
end

#setup_keepalives ⇒ Object

Set up the client keepalive consumer, keeping the Sensu client registry updated. The consumer receives JSON serialized client keepalives from the transport, parses them, and calls ‘update_client_registry()` with the client data to update the registry. Transport message acknowledgements are used to ensure the client registry is updated successfully. Keepalive JSON parsing errors are logged.



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# File 'lib/sensu/server/process.rb', line 172

def setup_keepalives
  @logger.debug("subscribing to keepalives")
  @transport.subscribe(:direct, "keepalives", "keepalives", :ack => true) do |message_info, message|
    @logger.debug("received keepalive", :message => message)
    begin
      client = Sensu::JSON.load(message)
      update_client_registry(client) do
        @transport.ack(message_info)
      end
    rescue Sensu::JSON::ParseError => error
      @logger.error("failed to parse keepalive payload", {
        :message => message,
        :error => error.to_s
      })
      @transport.ack(message_info)
    end
  end
end

#setup_leader_monitor ⇒ Object

Set up the leader monitor. A one-time timer is used to run ‘request_leader_exection()` in 2 seconds. A periodic timer is used to update the leader lock timestamp if the current process is the leader, or to run `request_leader_election(), every 10 seconds. The timers are stored in the timers hash under `:run`.



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# File 'lib/sensu/server/process.rb', line 1120

def setup_leader_monitor
  @timers[:run] << EM::Timer.new(2) do
    request_leader_election
  end
  @timers[:run] << EM::PeriodicTimer.new(10) do
    if @is_leader
      update_leader_lock
    else
      request_leader_election
    end
  end
end

#setup_results ⇒ Object

Set up the check result consumer. The consumer receives JSON serialized check results from the transport, parses them, and calls ‘process_check_result()` with the result data to be processed. Transport message acknowledgements are used to ensure that results make it to processing. The transport message acknowledgements are currently done in the next tick of the EventMachine reactor (event loop), as a flow control mechanism. Result JSON parsing errors are logged.



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# File 'lib/sensu/server/process.rb', line 690

def setup_results
  @logger.debug("subscribing to results")
  @transport.subscribe(:direct, "results", "results", :ack => true) do |message_info, message|
    begin
      result = Sensu::JSON.load(message)
      @logger.debug("received result", :result => result)
      process_check_result(result)
    rescue Sensu::JSON::ParseError => error
      @logger.error("failed to parse result payload", {
        :message => message,
        :error => error.to_s
      })
    end
    EM::next_tick do
      @transport.ack(message_info)
    end
  end
end

#start ⇒ Object

Start the Sensu server process, connecting to Redis, the Transport, and calling the ‘bootstrap()` method.



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# File 'lib/sensu/server/process.rb', line 1170

def start
  setup_connections do
    bootstrap
  end
end

#stop ⇒ Object

Stop the Sensu server process, pausing it, completing event handling in progress, closing the Redis and transport connections, and exiting the process (exit 0). After pausing the process, the process/daemon ‘@state` is set to `:stopping`.



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# File 'lib/sensu/server/process.rb', line 1227

def stop
  @logger.warn("stopping")
  pause
  @state = :stopping
  complete_in_progress do
    @redis.close if @redis
    @transport.close if @transport
    super
  end
end

#store_check_result(client, check) { ... } ⇒ Object

Store check result data. This method stores check result data and the 21 most recent check result statuses for a client/check pair, this history is used for event context and flap detection. The check execution timestamp is also stored, to provide an indication of how recent the data is. Check output is truncated by ‘truncate_check_output()` before it is stored.

Parameters:

  • client (Hash)
  • check (Hash)

Yields:

  • callback/block called after the check data has been

    stored (history, etc).



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# File 'lib/sensu/server/process.rb', line 352

def store_check_result(client, check)
  @logger.debug("storing check result", :check => check)
  result_key = "#{client[:name]}:#{check[:name]}"
  history_key = "history:#{result_key}"
  check_truncated = truncate_check_output(check)
  @redis.multi
  @redis.sadd("result:#{client[:name]}", check[:name])
  @redis.set("result:#{result_key}", Sensu::JSON.dump(check_truncated))
  @redis.sadd("ttl", result_key) if check[:ttl]
  @redis.rpush(history_key, check[:status])
  @redis.ltrim(history_key, -21, -1)
  @redis.exec do
    yield
  end
end

#transport_publish_options(subscription, message) ⇒ Array

Determine the Sensu Transport publish options for a subscription. If a subscription begins with a Transport pipe type, either “direct:” or “roundrobin:”, the subscription uses a direct Transport pipe. If a subscription does not specify a Transport pipe type, a fanout Transport pipe is used.

Parameters:

  • subscription (String)
  • message (String)

Returns:

  • (Array) —

    containing the Transport publish options: the Transport pipe type, pipe, and the message to be published.



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# File 'lib/sensu/server/process.rb', line 720

def transport_publish_options(subscription, message)
  _, raw_type = subscription.split(":", 2).reverse
  case raw_type
  when "direct", "roundrobin"
    [:direct, subscription, message]
  else
    [:fanout, subscription, message]
  end
end

#truncate_check_output(check) ⇒ Hash

Truncate check output. For metric checks, (‘“type”: “metric”`), check output is truncated to a single line and a maximum of 255 characters. Check output is currently left unmodified for standard checks.

Parameters:

  • check (Hash)

Returns:

  • (Hash) —

    check with truncated output.



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# File 'lib/sensu/server/process.rb', line 318

def truncate_check_output(check)
  case check[:type]
  when METRIC_CHECK_TYPE
    begin
      output_lines = check[:output].split("\n")
    rescue ArgumentError
      utf8_output = check[:output].encode("UTF-8", "binary", {
        :invalid => :replace,
        :undef => :replace,
        :replace => ""
      })
      output_lines = utf8_output.split("\n")
    end
    output = output_lines.first || check[:output]
    if output_lines.length > 1 || output.length > 255
      output = output[0..255] + "\n..."
    end
    check.merge(:output => output)
  else
    check
  end
end

#unsubscribe ⇒ Object

Unsubscribe from transport subscriptions (all of them). This method is called when there are issues with connectivity, or the process is stopping.



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# File 'lib/sensu/server/process.rb', line 1136

def unsubscribe
  @logger.warn("unsubscribing from keepalive and result queues")
  @transport.unsubscribe if @transport
end

#update_client_registry(client) {|success| ... } ⇒ Object

Update the Sensu client registry, stored in Redis. Sensu client data is used to provide additional event context and enable agent health monitoring. The client registry supports client signatures, unique string identifiers used for keepalive and result source verification. If a client has a signature, all further registry updates for the client must have the same signature. A client can begin to use a signature if one was not previously configured. JSON serialization is used for the stored client data.

Parameters:

  • client (Hash)

Yields:

  • (success) —

    passes success status to optional callback/block.

Yield Parameters:

  • success (TrueClass, FalseClass) —

    indicating if the client registry update was a success or the client data was discarded due to client signature mismatch.



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# File 'lib/sensu/server/process.rb', line 136

def update_client_registry(client)
  @logger.debug("updating client registry", :client => client)
  client_key = "client:#{client[:name]}"
  signature_key = "#{client_key}:signature"
  @redis.setnx(signature_key, client[:signature]) do |created|
    process_client_registration(client) if created
    @redis.get(signature_key) do |signature|
      if (signature.nil? || signature.empty?) && client[:signature]
        @redis.set(signature_key, client[:signature])
      end
      if signature.nil? || signature.empty? || (client[:signature] == signature)
        @redis.multi
        @redis.set(client_key, Sensu::JSON.dump(client))
        @redis.sadd("clients", client[:name])
        @redis.exec do
          yield(true) if block_given?
        end
      else
        @logger.warn("invalid client signature", {
          :client => client,
          :signature => signature
        })
        @logger.warn("not updating client in the registry", :client => client)
        yield(false) if block_given?
      end
    end
  end
end

#update_event_registry(event) {|process| ... } ⇒ Object

Update the event registry, stored in Redis. This method determines if event data warrants in the creation or update of event data in the registry. If a check ‘:status` is not `0`, or it has been flapping, an event is created/updated in the registry. If the event `:action` is `:resolve`, the event is removed (resolved) from the registry. If the previous conditions are not met and check `:type` is `metric`, the registry is not updated, but further event processing is required (`yield(true)`). JSON serialization is used when storing data in the registry.

Parameters:

  • event (Hash)

Yield Parameters:

  • process (TrueClass, FalseClass) —

    indicating if the event requires further processing.



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# File 'lib/sensu/server/process.rb', line 495

def update_event_registry(event)
  client_name = event[:client][:name]
  if event[:check][:status] != 0 || event[:action] == :flapping
    @redis.hset("events:#{client_name}", event[:check][:name], Sensu::JSON.dump(event)) do
      yield(true)
    end
  elsif event[:action] == :resolve &&
      (event[:check][:auto_resolve] != false || event[:check][:force_resolve])
    @redis.hdel("events:#{client_name}", event[:check][:name]) do
      yield(true)
    end
  elsif event[:check][:type] == METRIC_CHECK_TYPE
    yield(true)
  else
    yield(false)
  end
end

#update_leader_lock ⇒ Object

Updates the Sensu server leader lock timestamp. The current leader ID is retrieved from Redis and compared with the leader ID of the current process to determine if it is still the Sensu server leader. If the current process is still the leader, the leader lock timestamp is updated. If the current process is no longer the leader (regicide), ‘resign_as_leader()` is called for cleanup, so there is not more than one leader.



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# File 'lib/sensu/server/process.rb', line 1069

def update_leader_lock
  @redis.get("leader") do |current_leader_id|
    if current_leader_id == leader_id
      @redis.set("lock:leader", create_lock_timestamp) do
        @logger.debug("updated leader lock timestamp")
      end
    else
      @logger.warn("another sensu server has been elected as leader")
      resign_as_leader
    end
  end
end