newrelic: log more request context.

app/logical/danbooru_logger.rb

@@ -9,4 +9,33 @@ class DanbooruLogger
       ::NewRelic::Agent.notice_error(exception, expected: expected, custom_params: params)
     end
   end
+
+  def self.initialize(request, session, user)
+    add_attributes("request.params", request.params)
+    add_attributes("session.params", session.to_h)
+    add_attributes("user", { id: user.id, name: user.name, level: user.level_string, ip: request.remote_ip })
+  end
+
+  def self.add_attributes(prefix, hash)
+    return unless defined?(::NewRelic)
+
+    attributes = flatten_hash(hash).transform_keys { |key| "#{prefix}.#{key}" }
+    ::NewRelic::Agent.add_custom_attributes(attributes)
+  end
+
+  private
+
+  # flatten_hash({ foo: { bar: { baz: 42 } } })
+  # => { "foo.bar.baz" => 42 }
+  def self.flatten_hash(hash)
+    hash.each_with_object({}) do |(k, v), h|
+      if v.is_a?(Hash)
+        flatten_hash(v).map do|h_k, h_v|
+          h["#{k}.#{h_k}"] = h_v
+        end
+      else
+        h[k.to_s] = v
+      end
+    end
+  end
 end

app/logical/session_loader.rb

@@ -29,6 +29,7 @@ class SessionLoader
     update_last_ip_addr
     set_time_zone
     CurrentUser.user.unban! if CurrentUser.user.ban_expired?
+    DanbooruLogger.initialize(request, session, CurrentUser.user)
   end
 
 private