diff --git a/lib/datadog/tracing/contrib/http/distributed/fetcher.rb b/lib/datadog/tracing/contrib/http/distributed/fetcher.rb index b5c89368392..dc58f0491ca 100644 --- a/lib/datadog/tracing/contrib/http/distributed/fetcher.rb +++ b/lib/datadog/tracing/contrib/http/distributed/fetcher.rb @@ -8,13 +8,20 @@ module Tracing module Contrib module HTTP module Distributed - # Retrieves Rack formatted headers from HTTP headers. + # Retrieves HTTP headers from carrier. + # Headers will also match if Rack-formatted: + # 'my-header' will match 'my-header' and 'HTTP_MY_HEADER'. + # + # In case both variants are present, the verbatim match will be used. class Fetcher < Tracing::Distributed::Fetcher - # TODO: Don't assume Rack format. - # Make distributed tracing headers apathetic. # DEV: Should we try to parse both verbatim an Rack-formatted headers, # DEV: given Rack-formatted is the most common format in Ruby? def [](name) + # Try to fetch with the plain key + value = super(name) + return value if value && !value.empty? + + # If not found, try the Rack-formatted key rack_header = "HTTP-#{name}" rack_header.upcase! rack_header.tr!('-'.freeze, '_'.freeze) diff --git a/spec/datadog/tracing/contrib/http/distributed/fetcher_spec.rb b/spec/datadog/tracing/contrib/http/distributed/fetcher_spec.rb index 3922c19b6bc..07b74c2a028 100644 --- a/spec/datadog/tracing/contrib/http/distributed/fetcher_spec.rb +++ b/spec/datadog/tracing/contrib/http/distributed/fetcher_spec.rb @@ -29,14 +29,29 @@ context 'that is not empty' do let(:env) { { 'HTTP_MY_KEY' => 'value' } } it { is_expected.to eq('value') } + + context 'and a plain header' do + let(:env) { super().merge('my-key' => 'plain-match') } + + it 'prefers the plain header match' do + is_expected.to eq('plain-match') + end + end end end - context 'with a header not Rack formatted' do - let(:key) { 'my-key' } - let(:env) { { key => 'value' } } + context 'with a plain header associated' do + let(:key) { 'rack.session' } - it { is_expected.to be_nil } + context 'that is empty' do + let(:env) { { key => '' } } + it { is_expected.to be_nil } + end + + context 'that is not empty' do + let(:env) { { key => 'value' } } + it { is_expected.to eq('value') } + end end end end