Ruby `eval()` a string containing an expression, within the scope/context of a sandbox. This method is for filter attribute values starting with “eval:”, with the Ruby expression following the colon. A single variable is provided to the expression, `value`, equal to the corresponding event attribute value. Dot notation tokens in the expression, e.g. `:::mysql.user:::`, are substituted with the corresponding event data values prior to evaluation. The expression is expected to return a boolean value.
@param event [Hash] @param raw_eval_string [String] containing the Ruby
expression to be evaluated.
@param raw_value [Object] of the corresponding event
attribute value.
@return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 112 def eval_attribute_value(event, raw_eval_string, raw_value) eval_string = process_eval_string(event, raw_eval_string) unless eval_string.nil? begin value = Marshal.load(Marshal.dump(raw_value)) !!Sandbox.eval(eval_string, value) rescue StandardError, SyntaxError => error @logger.error("filter attribute eval error", { :event => event, :raw_eval_string => raw_eval_string, :raw_value => raw_value, :error => error.to_s }) false end else false end end
Determine if an event is filtered by an event filter, native or extension. This method first checks for the existence of a native filter, then checks for an extension if a native filter is not defined. The provided callback is called with a single parameter, indicating if the event was filtered by a filter. If a filter does not exist for the provided name, the event is not filtered.
@param filter_name [String] @param event [Hash] @yield [filtered] callback/block called with a single
parameter to indicate if the event was filtered.
@yieldparam filtered [TrueClass,FalseClass] indicating if the
event was filtered.
@yieldparam filter_name [String] name of the filter being evaluated
# File lib/sensu/server/filter.rb, line 229 def event_filter(filter_name, event) case when @settings.filter_exists?(filter_name) native_filter(filter_name, event) do |filtered| yield(filtered, filter_name) end when @extensions.filter_exists?(filter_name) extension_filter(filter_name, event) do |filtered| yield(filtered, filter_name) end else @logger.error("unknown filter", :filter_name => filter_name) yield(false, filter_name) end end
Determine if an event is filtered for a handler. If a handler specifies one or more filters, via `:filters` or `:filter`, the `event_filter()` method is called for each of them. If any of the filters return `true`, the event is filtered for the handler. If no filters are defined in the handler definition, the event is not filtered.
@param handler [Hash] definition. @param event [Hash] @yield [filtered] callback/block called with a single
parameter to indicate if the event was filtered.
@yieldparam filtered [TrueClass,FalseClass] indicating if the
event was filtered.
# File lib/sensu/server/filter.rb, line 258 def event_filtered?(handler, event) if handler.has_key?(:filters) || handler.has_key?(:filter) filter_list = Array(handler[:filters] || handler[:filter]).dup filter = Proc.new do |filter_list| filter_name = filter_list.shift if filter_name.nil? yield(false) else event_filter(filter_name, event) do |filtered| filtered ? yield(true) : EM.next_tick { filter.call(filter_list) } end end end filter.call(filter_list) else yield(false) end end
Determine if an event is filtered by a filter extension.
@param filter_name [String] @param event [Hash] @yield [filtered] callback/block called with a single
parameter to indicate if the event was filtered.
@yieldparam filtered [TrueClass,FalseClass] indicating if the
event was filtered.
@yieldparam filter_name [String] name of the filter being evaluated
# File lib/sensu/server/filter.rb, line 203 def extension_filter(filter_name, event) extension = @extensions[:filters][filter_name] if in_filter_time_windows?(extension.definition) extension.safe_run(event) do |output, status| yield(status == 0, filter_name) end else yield(false, filter_name) end end
Determine if all filter attribute values match those of the corresponding event attributes. Attributes match if the value objects are equivalent, are both hashes with matching key/value pairs (recursive), have equal string values, or evaluate to true (Ruby eval).
@param event [Hash] @param filter_attributes [Object] @param event_attributes [Object] @return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 142 def filter_attributes_match?(event, filter_attributes, event_attributes=nil) event_attributes ||= event filter_attributes.all? do |key, value_one| value_two = event_attributes[key] case when value_one == value_two true when value_one.is_a?(Hash) && value_two.is_a?(Hash) filter_attributes_match?(event, value_one, value_two) when value_one.to_s == value_two.to_s true when value_one.is_a?(String) && value_one.start_with?(EVAL_PREFIX) eval_attribute_value(event, value_one, value_two) else false end end end
Attempt to filter an event for a handler. This method will check to see if handling is disabled, if the event action is handled, if the event check severity is handled, if the handler is subdued, and if the event is filtered by any of the filters specified in the handler definition.
@param handler [Hash] definition. @param event [Hash] @yield [event] callback/block called if the event has not been
filtered.
@yieldparam event [Hash]
# File lib/sensu/server/filter.rb, line 288 def filter_event(handler, event) details = {:handler => handler, :event => event} filter_message = case when handling_disabled?(event) "event handling disabled for event" when !handle_action?(handler, event) "handler does not handle action" when !handle_severity?(handler, event) "handler does not handle event severity" when handler_silenced?(handler, event) "handler is silenced" end if filter_message @logger.info(filter_message, details) @in_progress[:events] -= 1 if @in_progress else event_filtered?(handler, event) do |filtered, filter_name| unless filtered yield(event) else details[:filter] = filter_name @logger.info("event was filtered", details) @in_progress[:events] -= 1 if @in_progress end end end end
Determine if an event with an action should be handled. An event action of `:flapping` indicates that the event state is flapping, and the event should not be handled unless its handler has `:handle_flapping` set to `true`.
@param handler [Hash] definition. @param event [Hash] @return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 35 def handle_action?(handler, event) event[:action] != :flapping || (event[:action] == :flapping && !!handler[:handle_flapping]) end
Determine if an event with a check severity will be handled. Event handlers can specify the check severities they will handle, using the definition attribute `:severities`. The possible severities are “ok”, “warning”, “critical”, and “unknown”. Handler severity filtering is bypassed when the event `:action` is `:resolve`, if the check history contains one of the specified severities since the last OK result.
@param handler [Hash] definition. @param event [Hash] @return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 51 def handle_severity?(handler, event) if handler.has_key?(:severities) case event[:action] when :resolve event[:check][:history].reverse[1..-1].any? do |status| if status.to_i == 0 break false end severity = SEVERITIES[status.to_i] || "unknown" handler[:severities].include?(severity) end else severity = SEVERITIES[event[:check][:status]] || "unknown" handler[:severities].include?(severity) end else true end end
Determine if an event handler is silenced.
@param handler [Hash] definition. @param event [Hash] @return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 13 def handler_silenced?(handler, event) event[:silenced] && !handler[:handle_silenced] end
Determine if handling is disabled for an event. Check definitions can disable event handling with an attribute, `:handle`, by setting it to `false`.
@param event [Hash] @return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 23 def handling_disabled?(event) event[:check][:handle] == false end
Determine if a filter is to be evoked for the current time. A filter can be configured with a time window defining when it is to be evoked, e.g. Monday through Friday, 9-5.
@param filter [Hash] definition. @return [TrueClass, FalseClass]
# File lib/sensu/server/filter.rb, line 167 def in_filter_time_windows?(filter) if filter[:when] in_time_windows?(filter[:when]) else true end end
Determine if an event is filtered by a native filter.
@param filter_name [String] @param event [Hash] @yield [filtered] callback/block called with a single
parameter to indicate if the event was filtered.
@yieldparam filtered [TrueClass,FalseClass] indicating if the
event was filtered.
@yieldparam filter_name [String] name of the filter being evaluated
# File lib/sensu/server/filter.rb, line 184 def native_filter(filter_name, event) filter = @settings[:filters][filter_name] if in_filter_time_windows?(filter) matched = filter_attributes_match?(event, filter[:attributes]) yield(filter[:negate] ? matched : !matched, filter_name) else yield(false, filter_name) end end
Process a filter eval attribute, a Ruby `eval()` string containing an expression to be evaluated within the scope/context of a sandbox. This methods strips away the expression prefix, `eval:`, and substitues any dot notation tokens with the corresponding event data values. If there are unmatched tokens, this method will return `nil`.
@event [Hash] @raw_eval_string [String] @return [String] processed eval string.
# File lib/sensu/server/filter.rb, line 81 def process_eval_string(event, raw_eval_string) eval_string = raw_eval_string.slice(5..-1) eval_string, unmatched_tokens = substitute_tokens(eval_string, event) if unmatched_tokens.empty? eval_string else @logger.error("filter eval unmatched tokens", { :raw_eval_string => raw_eval_string, :unmatched_tokens => unmatched_tokens, :event => event }) nil end end