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rack_env_getter.rb
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rack_env_getter.rb
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# frozen_string_literal: true
# Copyright The OpenTelemetry Authors
#
# SPDX-License-Identifier: Apache-2.0
module OpenTelemetry
module Common
module Propagation
# The RackEnvGetter class provides a common methods for reading
# keys from a rack environment. It abstracts away the rack-normalization
# process so that keys can be looked up without having to transform them
# first. With this class you can get +traceparent+ instead of
# +HTTP_TRACEPARENT+
class RackEnvGetter
# Converts key into a rack-normalized key and reads it from the carrier.
# Useful for extract operations.
def get(carrier, key)
carrier[to_rack_key(key)] || carrier[key]
end
# Reads all keys from a carrier and converts them from the rack-normalized
# form to the original. The resulting keys will be lowercase and
# underscores will be replaced with dashes.
def keys(carrier)
carrier.keys.map(&method(:from_rack_key))
end
private
def to_rack_key(key)
ret = 'HTTP_' + key
ret.tr!('-', '_')
ret.upcase!
ret
end
def from_rack_key(key)
start = key.start_with?('HTTP_') ? 5 : 0
ret = key[start..-1]
ret.tr!('_', '-')
ret.downcase!
ret
end
end
end
end
end