Set custom log attributes using newrelic.yml or environment variables

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## dev
 
-Version <dev> of the agent adds log-level filtering, an API to add custom attributes to logs, and updated instrumentation for Action Cable. It also provides fixes for how `Fiber` args are treated, Code-Level Metrics, and `NewRelic::Agent::Logging::DecoratingFormatter#clear_tags!` being incorrectly private.
+Version <dev> of the agent adds log-level filtering, adds custom attributes for log events, and updates instrumentation for Action Cable. It also provides fixes for how `Fiber` args are treated, Code-Level Metrics, and `NewRelic::Agent::Logging::DecoratingFormatter#clear_tags!` being incorrectly private.
 
 - **Feature: Filter forwarded logs based on level**
 
@@ -14,15 +14,22 @@ Version <dev> of the agent adds log-level filtering, an API to add custom attrib
 
   This setting uses [Ruby's Logger::Severity constants integer values](https://github.com/ruby/ruby/blob/master/lib/logger/severity.rb#L6-L17) to determine precedence.
 
-- **Feature: Custom attributes for logs API**
+- **Feature: Custom attributes for logs**
 
-  You can now add custom attributes to your log events using `NewRelic::Agent.add_custom_log_attributes`.
+  You can now add custom attributes to log events forwarded to New Relic! You can pass these attributes using an API and/or a configuration option.
 
-  For example: `NewRelic::Agent.add_custom_log_attributes(dyno: ENV['DYNO'], pod_name: ENV['POD_NAME'])`, will add the attributes `dyno` and `pod_name` to your log events. Attributes passed to this API will be added to all log events.
+  | Configuration name          | Default | Behavior                                               |
+  | --------------------------- | ------- | ------------------------------------------------------ |
+  | `application_logging.forwarding.custom_attributes` | `{}` | A hash with key/value pairs to add as custom attributes to all log events forwarded to New Relic. If sending using an environment variable, the value must be formatted like: "key1=value1,key2=value2" |
+
+
+  Call the API using `NewRelic::Agent.add_custom_log_attributes` and passing your attributes as a hash. For example, you could call: `NewRelic::Agent.add_custom_log_attributes(dyno: ENV['DYNO'], pod_name: ENV['POD_NAME'])`, to add the attributes `dyno` and `pod_name` to your log events.
+
+  Attributes passed to the API or the configuration will be added to all log events.
 
-  Thanks to [@rajpawar02](https://github.com/rajpawar02) for raising this issue and [@askreet](https://github.com/askreet) for helping us with the solution. [Issue#1141](https://github.com/newrelic/newrelic-ruby-agent/issues/1141), [PR#2084](https://github.com/newrelic/newrelic-ruby-agent/pull/2084)
+  Thanks to [@rajpawar02](https://github.com/rajpawar02) for raising this issue and [@askreet](https://github.com/askreet) for helping us with the solution. [Issue#1141](https://github.com/newrelic/newrelic-ruby-agent/issues/1141), [PR#2084](https://github.com/newrelic/newrelic-ruby-agent/pull/2084), [PR#2087](https://github.com/newrelic/newrelic-ruby-agent/pull/2087)
 
-- **Feature: Instrument transmit_subscription_* Action Cable actions**
+- **Feature: Instrument transmit_subscription-related Action Cable actions**
 
   This change subscribes the agent to the Active Support notifications for:
     * `transmit_subscription_confirmation.action_cable`

lib/new_relic/agent/configuration/default_source.rb

@@ -211,6 +211,22 @@ def self.convert_to_list(value)
           end
         end
 
+        def self.convert_to_hash(value)
+          return value if value.is_a?(Hash)
+
+          if value.is_a?(String)
+            return value.split(',').each_with_object({}) do |item, hash|
+              key, value = item.split('=')
+              hash[key] = value
+            end
+          end
+
+          raise ArgumentError.new(
+            "Config value '#{value}' of " \
+            "class #{value.class} couldn't be turned into a Hash."
+          )
+        end
+
         SEMICOLON = ';'.freeze
         def self.convert_to_list_on_semicolon(value)
           case value
@@ -771,6 +787,14 @@ def self.enforce_fallback(allowed_values: nil, fallback: nil)
               * "unknown"
           DESCRIPTION
         },
+        :'application_logging.forwarding.custom_attributes' => {
+          :default => {},
+          :public => true,
+          :type => Hash,
+          :transform => DefaultSource.method(:convert_to_hash),
+          :allowed_from_server => false,
+          :description => 'A hash with key/value pairs to add as custom attributes to all log events forwarded to New Relic. If sending using an environment variable, the value must be formatted like: "key1=value1,key2=value2"'
+        },
         :'application_logging.forwarding.max_samples_stored' => {
           :default => 10000,
           :public => true,

lib/new_relic/agent/log_event_aggregator.rb

@@ -38,6 +38,7 @@ class LogEventAggregator < EventAggregator
       FORWARDING_ENABLED_KEY = :'application_logging.forwarding.enabled'
       DECORATING_ENABLED_KEY = :'application_logging.local_decorating.enabled'
       LOG_LEVEL_KEY = :'application_logging.forwarding.log_level'
+      CUSTOM_ATTRIBUTES_KEY = :'application_logging.forwarding.custom_attributes'
 
       attr_reader :attributes
 
@@ -181,6 +182,8 @@ def register_for_done_configuring(events)
           record_configuration_metric(METRICS_SUPPORTABILITY_FORMAT, METRICS_ENABLED_KEY)
           record_configuration_metric(FORWARDING_SUPPORTABILITY_FORMAT, FORWARDING_ENABLED_KEY)
           record_configuration_metric(DECORATING_SUPPORTABILITY_FORMAT, DECORATING_ENABLED_KEY)
+
+          add_custom_attributes(NewRelic::Agent.config[CUSTOM_ATTRIBUTES_KEY])
         end
       end
 

test/new_relic/agent/configuration/default_source_test.rb

@@ -254,6 +254,25 @@ def test_instrumentation_logger_matches_application_logging_disabled
       end
     end
 
+    def test_convert_to_hash_returns_hash
+      result = {'key1' => 'value1', 'key2' => 'value2'}
+
+      assert_equal(DefaultSource.convert_to_hash(result), result)
+    end
+
+    def test_convert_to_hash_with_string
+      value = 'key1=value1,key2=value2'
+      result = {'key1' => 'value1', 'key2' => 'value2'}
+
+      assert_equal(DefaultSource.convert_to_hash(value), result)
+    end
+
+    def test_convert_to_hash_raises_error_with_wrong_data_type
+      value = [1, 2, 3]
+
+      assert_raises(ArgumentError) { DefaultSource.convert_to_hash(value) }
+    end
+
     def get_config_value_class(value)
       type = value.class
 

test/new_relic/agent/log_event_attributes_test.rb

@@ -211,5 +211,18 @@ def test_drops_attribute_pair_if_invalid_value_class
         logger.verify
       end
     end
+
+    def test_log_attributes_from_config
+      key = 'configured'
+      value = 'value'
+
+      with_config(
+        :'application_logging.forwarding.custom_attributes' => {key => value}
+      ) do
+        NewRelic::Agent.config.notify_server_source_added
+
+        assert_includes(common_attributes_from_melt, key)
+      end
+    end
   end
 end