Support spaces in environment variable lists

lib/datadog/core/configuration/settings.rb

@@ -412,7 +412,7 @@ def initialize(*_)
                     Tracing::Configuration::Ext::Distributed::PROPAGATION_STYLE_DATADOG,
                     Tracing::Configuration::Ext::Distributed::PROPAGATION_STYLE_B3,
                     Tracing::Configuration::Ext::Distributed::PROPAGATION_STYLE_B3_SINGLE_HEADER
-                  ]
+                  ], comma_separated_only: true
                 )
               end
 
@@ -430,7 +430,7 @@ def initialize(*_)
               o.default do
                 env_to_list(
                   Tracing::Configuration::Ext::Distributed::ENV_PROPAGATION_STYLE_INJECT,
-                  [Tracing::Configuration::Ext::Distributed::PROPAGATION_STYLE_DATADOG] # Only inject Datadog headers by default
+                  [Tracing::Configuration::Ext::Distributed::PROPAGATION_STYLE_DATADOG], comma_separated_only: true # Only inject Datadog headers by default
                 )
               end
 

lib/datadog/core/environment/variable_helpers.rb

@@ -24,10 +24,34 @@ def env_to_float(var, default = nil)
           var && ENV.key?(var) ? ENV[var].to_f : default
         end
 
-        def env_to_list(var, default = [])
+        # Parses comma- or space-separated lists.
+        #
+        # If a comma is present, then the list is considered comma-separated.
+        # Otherwise, it is considered space-separated.
+        #
+        # After the entries are separated, commas and whitespaces that are
+        # either trailing or leading are trimmed.
+        #
+        # Empty entries, after trimmed, are also removed from the result.
+        def env_to_list(var, default = [], comma_separated_only: false)
           var = decode_array(var)
           if var && ENV.key?(var)
-            ENV[var].split(',').map(&:strip)
+            value = ENV[var]
+
+            values = if value.include?(',') || comma_separated_only
+                       value.split(',')
+                     else
+                       value.split # space splitting is the default
+                     end
+
+            values.map! do |v|
+              v.gsub!(/\A[\s,]*|[\s,]*\Z/, '')
+
+              v.empty? ? nil : v
+            end
+
+            values.compact!
+            values
           else
             default
           end

spec/datadog/core/environment/variable_helpers_spec.rb

@@ -174,7 +174,7 @@
       end
     end
 
-    context 'when env var is set as' do
+    context 'when env var is set' do
       include_context 'env var'
 
       context '\'\'' do
@@ -201,11 +201,45 @@
         it { is_expected.to eq(%w[1 2]) }
       end
 
-      context ' 1 , 2 , 3 ' do
-        let(:env_value) { ' 1 , 2 , 3 ' }
+      context ' 1 , 2 ,  3 ' do
+        let(:env_value) { ' 1 , 2 ,  3 ' }
+
+        it { is_expected.to eq(%w[1 2 3]) }
+      end
+
+      context '1 2 3' do
+        let(:env_value) { '1 2 3' }
 
         it { is_expected.to eq(%w[1 2 3]) }
       end
+
+      context '1,2 3' do
+        let(:env_value) { '1,2 3' }
+
+        it { is_expected.to eq(['1', '2 3']) }
+      end
+
+      context ' 1  2   3 ' do
+        let(:env_value) { ' 1  2   3 ' }
+
+        it { is_expected.to eq(%w[1 2 3]) }
+      end
+
+      context '1,, ,2,3,' do
+        let(:env_value) { '1,, ,2,3,' }
+
+        it { is_expected.to eq(%w[1 2 3]) }
+      end
+
+      context 'and comma_separated_only is set' do
+        subject(:env_to_list) { variable_helpers.env_to_list(var, comma_separated_only: true) }
+
+        context 'B3 single header ' do
+          let(:env_value) { 'B3 single header ' }
+
+          it { is_expected.to eq(['B3 single header']) }
+        end
+      end
     end
   end
 end