fix(examples): address dice roller PR review feedback

Remove redundant metrics and logs configuration code that is already
handled by OpenTelemetry::SDK.configure through configuration hooks.
Improve validation and code organization based on review comments.

Changes:
- Remove manual metrics/logs provider setup (handled by SDK configurator)
- Use OpenTelemetry.logger_provider.shutdown for consistency
- Move rolls assignment after validation for better code flow
- Add multi-exporter example to README
- Document OTEL_LOG_LEVEL default value
- Fix markdown linting errors

Addresses review feedback from PR #2048

Signed-off-by: Arjun Rajappa <arjun.rajappa@ibm.com>

Author: arjun-rajappa

examples/dice_roller/README.md

@@ -48,6 +48,15 @@ OTEL_LOGS_EXPORTER=otlp \
 OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 \
 OTEL_SERVICE_NAME=dice_roller \
 ruby app.rb
+You can also export your telemetry to more than one location. To send to an OpenTelemetry Collector and to the console, set the exporter env vars:
+
+```bash
+OTEL_TRACES_EXPORTER=otlp,console \
+OTEL_METRICS_EXPORTER=otlp,console \
+OTEL_LOGS_EXPORTER=otlp,console \
+OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318 \
+OTEL_SERVICE_NAME=dice_roller \
+ruby app.rb
 ```
 
 ---
@@ -177,4 +186,4 @@ All Ruby `Logger` output is bridged to OpenTelemetry via
 | `OTEL_METRICS_EXPORTER`        | `console`               | Metrics exporter (`console` or `otlp`)                    |
 | `OTEL_LOGS_EXPORTER`           | `console`               | Logs exporter (`console` or `otlp`)                       |
 | `OTEL_EXPORTER_OTLP_ENDPOINT`  | `http://localhost:4318` | OTLP endpoint                                             |
-| `OTEL_LOG_LEVEL`               | _(unset)_               | OTel internal diagnostic log level (e.g. `debug`)         |
+| `OTEL_LOG_LEVEL`               | _(unset)_               | OTel internal log level (e.g. `debug`, default: `info`)   |

examples/dice_roller/instrumented/app.rb

@@ -38,16 +38,15 @@ class DiceApp < Sinatra::Base
     rolls_param = params[:rolls]
     player      = params[:player]
 
-    # Default rolls to 1 if not provided
-    rolls = rolls_param.nil? ? 1 : rolls_param.to_i
-
     # Validate: must be a number
     unless rolls_param.nil? || rolls_param.match?(/\A-?\d+\z/)
       status 400
       LOGGER.warn "Invalid rolls parameter: #{rolls_param}"
-      return { status: 'error', message: 'Parameter rolls must be a positive integer' }.to_json
+      return { status: 'error', message: 'Parameter rolls must be an integer' }.to_json
     end
 
+    rolls = rolls_param.nil? ? 1 : rolls_param.to_i
+
     dice = Dice.new
 
     begin

examples/dice_roller/instrumented/otel.rb

@@ -48,38 +48,19 @@
 end
 
 # ---------------------------------------------------------------------------
-# Metrics SDK — add a console reader so metrics are visible without a backend
+# Metrics and Logs Configuration
 # ---------------------------------------------------------------------------
-case ENV['OTEL_METRICS_EXPORTER']
-when 'otlp'
-  otlp_metric_exporter = OpenTelemetry::Exporter::OTLP::Metrics::MetricsExporter.new
-  OpenTelemetry.meter_provider.add_metric_reader(
-    OpenTelemetry::SDK::Metrics::Export::PeriodicMetricReader.new(exporter: otlp_metric_exporter)
-  )
-else
-  console_metric_exporter = OpenTelemetry::SDK::Metrics::Export::ConsoleMetricPullExporter.new
-  OpenTelemetry.meter_provider.add_metric_reader(console_metric_exporter)
-end
-
-# ---------------------------------------------------------------------------
-# Logs SDK — wire up a console exporter and bridge Ruby's Logger
-# ---------------------------------------------------------------------------
-logs_logger_provider = OpenTelemetry::SDK::Logs::LoggerProvider.new
-case ENV['OTEL_LOGS_EXPORTER']
-when 'otlp'
-  log_processor = OpenTelemetry::SDK::Logs::Export::BatchLogRecordProcessor.new(
-    OpenTelemetry::Exporter::OTLP::Logs::LogsExporter.new
-  )
-  logs_logger_provider.add_log_record_processor(log_processor)
-else
-  log_processor = OpenTelemetry::SDK::Logs::Export::SimpleLogRecordProcessor.new(
-    OpenTelemetry::SDK::Logs::Export::ConsoleLogRecordExporter.new
-  )
-  logs_logger_provider.add_log_record_processor(log_processor)
-end
-OpenTelemetry.logger_provider = logs_logger_provider
-
+# NOTE: Metrics and logs providers are automatically configured by
+# OpenTelemetry::SDK.configure above based on the OTEL_METRICS_EXPORTER
+# and OTEL_LOGS_EXPORTER environment variables. The SDK handles:
+#
+# - Creating the meter_provider and logger_provider
+# - Setting up appropriate exporters (console, otlp, etc.)
+# - Adding metric readers and log record processors
+#
+# However, we still need to explicitly shutdown the providers at exit
+# to ensure all telemetry data is flushed before the application terminates.
 at_exit do
   OpenTelemetry.meter_provider.shutdown
-  logs_logger_provider.shutdown
+  OpenTelemetry.logger_provider.shutdown
 end

examples/dice_roller/uninstrumented/app.rb

@@ -29,16 +29,15 @@ class DiceApp < Sinatra::Base
     rolls_param = params[:rolls]
     player      = params[:player]
 
-    # Default rolls to 1 if not provided
-    rolls = rolls_param.nil? ? 1 : rolls_param.to_i
-
     # Validate: must be a number
     unless rolls_param.nil? || rolls_param.match?(/\A-?\d+\z/)
       status 400
       LOGGER.warn "Invalid rolls parameter: #{rolls_param}"
-      return { status: 'error', message: 'Parameter rolls must be a positive integer' }.to_json
+      return { status: 'error', message: 'Parameter rolls must be an integer' }.to_json
     end
 
+    rolls = rolls_param.nil? ? 1 : rolls_param.to_i
+
     dice = Dice.new
 
     begin