Make logger dependencies optional and add stdlib Logger support

- Move semantic_logger from runtime to development dependency
- Make semantic_logger optional with graceful fallback
- Add stdlib Logger integration via stdlib_formatter method
- Update README with stdlib Logger documentation
- Improves flexibility for customer integration by removing required dependencies

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jkebinger

Gemfile

@@ -9,9 +9,8 @@ gem 'uuid'
 
 gem 'activesupport', '>= 4'
 
-gem 'semantic_logger', '!= 4.16.0', require: "semantic_logger/sync"
-
-group :development do
+ group :development do
+  gem 'semantic_logger', '!= 4.16.0', require: "semantic_logger/sync"
   gem 'allocation_stats'
   gem 'benchmark-ips'
   gem 'bundler'

README.md

@@ -66,7 +66,11 @@ end
 
 ## Dynamic Log Levels
 
-Reforge supports dynamic log level management through SemanticLogger integration. This allows you to change log levels in real-time without redeploying your application.
+Reforge supports dynamic log level management for Ruby logging frameworks. This allows you to change log levels in real-time without redeploying your application.
+
+Supported loggers:
+- SemanticLogger (optional dependency)
+- Ruby stdlib Logger
 
 ### Setup with SemanticLogger
 
@@ -127,6 +131,26 @@ on_worker_boot do
 end
 ```
 
+### With Ruby stdlib Logger
+
+If you're using Ruby's standard library Logger, you can use a dynamic formatter:
+
+```ruby
+require "logger"
+require "sdk-reforge"
+
+client = Reforge::Client.new(
+  sdk_key: ENV['REFORGE_BACKEND_SDK_KEY'],
+  logger_key: 'log-levels.default' # optional, this is the default
+)
+
+logger = Logger.new($stdout)
+logger.level = Logger::DEBUG # Set to most verbose level, Reforge will handle filtering
+logger.formatter = client.log_level_client.stdlib_formatter('MyApp')
+```
+
+The formatter will check dynamic log levels from Reforge and only output logs that meet the configured threshold.
+
 ### Configuration
 
 In Reforge Launch, create a `LOG_LEVEL_V2` config with your desired key (default: `log-levels.default`). The config will be evaluated with the following context:

lib/reforge/log_level_client.rb

@@ -19,8 +19,19 @@ def initialize(base_client)
       @base_client = base_client
     end
 
+    # Map from Ruby stdlib Logger severity levels to our LogLevel symbols
+    # Ruby Logger levels: DEBUG=0, INFO=1, WARN=2, ERROR=3, FATAL=4, UNKNOWN=5
+    STDLIB_LOGGER_LEVELS = {
+      0 => :debug,  # Logger::DEBUG
+      1 => :info,   # Logger::INFO
+      2 => :warn,   # Logger::WARN
+      3 => :error,  # Logger::ERROR
+      4 => :fatal,  # Logger::FATAL
+      5 => :fatal   # Logger::UNKNOWN (treat as fatal)
+    }.freeze
+
     # Check if a log message should be logged based on severity and logger path
-    # @param severity [Integer] SemanticLogger severity level (0-5)
+    # @param severity [Integer] Logger severity level (0-5 for SemanticLogger, 0-5 for stdlib Logger)
     # @param path [String] Logger path/name
     # @return [Boolean] true if the message should be logged
     def should_log?(severity, path)
@@ -32,13 +43,47 @@ def should_log?(severity, path)
     # SemanticLogger filter integration
     # @param log [SemanticLogger::Log] The log entry to filter
     # @return [Boolean] true if the log should be output
+    # Note: This method requires semantic_logger gem to be installed
     def semantic_filter(log)
+      unless defined?(SemanticLogger)
+        LOG.warn "semantic_filter called but SemanticLogger is not loaded. Install the 'semantic_logger' gem to use this feature."
+        return true # Allow all logs through if SemanticLogger is not available
+      end
+
       class_path = class_path_name(log.name)
       level = SemanticLogger::Levels.index(log.level)
       log.named_tags.merge!({ path: class_path })
       should_log?(level, class_path)
     end
 
+    # Returns a formatter proc for use with Ruby stdlib Logger
+    # Usage:
+    #   logger = Logger.new($stdout)
+    #   logger.formatter = client.log_level_client.stdlib_formatter('MyApp')
+    # @param logger_name [String] The name/path of the logger
+    # @return [Proc] A formatter proc that respects dynamic log levels
+    def stdlib_formatter(logger_name)
+      proc do |severity, datetime, progname, msg|
+        # Convert Logger severity string to integer (DEBUG=0, INFO=1, WARN=2, ERROR=3, FATAL=4)
+        severity_int = case severity
+                      when 'DEBUG' then 0
+                      when 'INFO' then 1
+                      when 'WARN' then 2
+                      when 'ERROR' then 3
+                      when 'FATAL', 'UNKNOWN' then 4
+                      else 1
+                      end
+
+        # Check if we should log this message
+        if should_log?(severity_int, logger_name)
+          # Default formatting
+          "[#{datetime.strftime('%Y-%m-%d %H:%M:%S.%L')}] #{severity} -- #{progname}: #{msg}\n"
+        else
+          nil # Don't output the log
+        end
+      end
+    end
+
     # Get the log level for a given logger name
     # Returns a LogLevel symbol (:trace, :debug, :info, :warn, :error, :fatal)
     # Defaults to :debug if no config is found

lib/sdk-reforge.rb

@@ -5,7 +5,12 @@ module Reforge
   VERSION = File.read(File.dirname(__FILE__) + '/../VERSION').strip
 end
 
-require 'semantic_logger'
+begin
+  require 'semantic_logger'
+rescue LoadError
+  # semantic_logger is optional - only needed for dynamic log level filtering
+end
+
 require 'reforge/internal_logger'
 require 'concurrent/atomics'
 require 'concurrent'

sdk-reforge.gemspec

@@ -11,7 +11,7 @@ Gem::Specification.new do |s|
   s.required_rubygems_version = Gem::Requirement.new(">= 0".freeze) if s.respond_to? :required_rubygems_version=
   s.require_paths = ["lib".freeze]
   s.authors = ["Jeff Dwyer".freeze]
-  s.date = "2025-10-07"
+  s.date = "2025-10-23"
   s.description = "Feature Flags, Live Config as a service".freeze
   s.email = "jeff.dwyer@reforge.com.cloud".freeze
   s.extra_rdoc_files = [
@@ -20,6 +20,7 @@ Gem::Specification.new do |s|
     "README.md"
   ]
   s.files = [
+    ".DS_Store",
     ".envrc.sample",
     ".github/CODEOWNERS",
     ".github/pull_request_template.md",
@@ -73,6 +74,8 @@ Gem::Specification.new do |s|
     "lib/reforge/internal_logger.rb",
     "lib/reforge/javascript_stub.rb",
     "lib/reforge/local_config_parser.rb",
+    "lib/reforge/log_level.rb",
+    "lib/reforge/log_level_client.rb",
     "lib/reforge/murmer3.rb",
     "lib/reforge/options.rb",
     "lib/reforge/periodic_sync.rb",
@@ -116,6 +119,7 @@ Gem::Specification.new do |s|
     "test/test_internal_logger.rb",
     "test/test_javascript_stub.rb",
     "test/test_local_config_parser.rb",
+    "test/test_log_level_client.rb",
     "test/test_logger_initialization.rb",
     "test/test_options.rb",
     "test/test_prefab.rb",
@@ -138,7 +142,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency(%q<ld-eventsource>.freeze, [">= 0"])
   s.add_runtime_dependency(%q<uuid>.freeze, [">= 0"])
   s.add_runtime_dependency(%q<activesupport>.freeze, [">= 4"])
-  s.add_runtime_dependency(%q<semantic_logger>.freeze, ["!= 4.16.0"])
+  s.add_development_dependency(%q<semantic_logger>.freeze, ["!= 4.16.0"])
   s.add_development_dependency(%q<allocation_stats>.freeze, [">= 0"])
   s.add_development_dependency(%q<benchmark-ips>.freeze, [">= 0"])
   s.add_development_dependency(%q<bundler>.freeze, [">= 0"])