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81 lines
3.2 KiB
Ruby
81 lines
3.2 KiB
Ruby
# frozen_string_literal: true
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#
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# Copyright 2017 Holger Just
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#
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# This software may be modified and distributed under the terms
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# of the MIT license. See the LICENSE.txt file for details.
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require 'rackstash/filters/clear_color'
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require 'rackstash/filters/rename'
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require 'rackstash/filters/replace'
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require 'rackstash/filters/skip_event'
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require 'rackstash/filters/truncate_message'
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module Rackstash
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# Filters are part of a {Flow} where they can alter the log event before it is
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# passed to the encoder and finally to the adapter. With filters, you can add,
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# change or delete fields. Since each flow uses its own copy of a log event,
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# you can use a different set of filters per flow and can adapt the event
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# anyway you require.
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#
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# You can e.g. remove unenessary fields, anonymize logged IP addresses or
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# filter messages. In its `call` method, the passed event hash can be mutated
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# in any way. Since the event hash includes an array of {Message} objects in
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# `event["messages"]` which provide the original severity and timestamp of
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# each logged message, you can also retrospectively filter the logged messages.
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#
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# A filter can be any object responding to `call`, e.g. a Proc or a concrete
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# class inside this module.
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module Filters
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# Create a new filter instance from the specified class and the given
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# arguments. The class can be given as an actual class or as the name of a
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# filter in which case we are resolving it to a class defined inside the
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# {Rackstash::Filters} namespace.
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#
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# @param klass [Class, Symbol, String] a description of the class from which
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# we are creating a new filter object. When giving a `Class`, we are using
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# it as is. When giving a `String` or `Symbol`, we are determining the
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# associated class from the {Rackstash::Filters} module and create an
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# instance of that.
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# @param args [Array] an optional list of arguments which is passed to the
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# initializer for the new filter object.
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# @raise [TypeError] if we can not create a new Filter object from `class`
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# @raise [NameError] if we could not find a filter class for the specified
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# class name
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# @return [Object] a new filter object
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def self.build(klass, *args, &block)
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case klass
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when Class
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klass.new(*args, &block)
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when Symbol, String
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filter_class_name = klass.to_s
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.sub(/^[a-z\d]*/) { $&.capitalize }
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.gsub(/(?:_)([a-z\d]*)/) { $1.capitalize }
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.to_sym
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filter_class = const_get(filter_class_name, false)
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filter_class.new(*args, &block)
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else
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raise TypeError, "Can not build filter for #{klass.inspect}"
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end
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end
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# @return [Hash<Symbol => Class>] a Hash with names of filters and their
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# respective classes which can be used with {Filters.build} to create a
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# new filter object
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def self.known
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constants.each_with_object({}) do |const, known|
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filter_class = const_get(const, false)
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next unless filter_class.is_a?(Class)
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filter_class_name = const.to_s
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.gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
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.gsub(/([a-z\d])([A-Z])/, '\1_\2')
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.downcase
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.to_sym
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known[filter_class_name] = filter_class
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end
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end
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end
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end
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