Line data    Source code

       1              : // Licensed under the Apache License, Version 2.0
       2              : // Copyright 2025, Michael Bushe, All rights reserved.
       3              : 
       4              : import 'dart:io' as io;
       5              : 
       6              : import 'env_constants.dart';
       7              : import 'env_from_define.dart';
       8              : import 'environment_service.dart';
       9              : 
      10              : /// IO implementation of the environment service.
      11              : ///
      12              : /// This implementation is used on all platforms except web (Dart VM, Flutter
      13              : /// native, and Flutter desktop).
      14              : ///
      15              : /// Environment variable lookup priority:
      16              : /// 1. String.fromEnvironment (--dart-define values)
      17              : /// 2. io.Platform.environment (system environment variables)
      18              : ///
      19              : /// The implementation uses String.fromEnvironment with empty string as the
      20              : /// default value. If the result is empty, it falls back to checking
      21              : /// io.Platform.environment. This allows --dart-define values to take
      22              : /// precedence over system environment variables, as per OpenTelemetry
      23              : /// specification recommendations.
      24              : class EnvironmentService implements EnvironmentServiceInterface {
      25          219 :   static final EnvironmentService _instance = EnvironmentService._();
      26              : 
      27              :   /// The singleton instance of the EnvironmentService.
      28          146 :   static EnvironmentService get instance => _instance;
      29              : 
      30           73 :   EnvironmentService._();
      31              : 
      32              :   /// Gets the value of an environment variable.
      33              :   ///
      34              :   /// Returns the value from the first available source:
      35              :   /// 1. String.fromEnvironment if defined via --dart-define
      36              :   /// 2. io.Platform.environment (system environment variables)
      37              :   /// 3. null if not found
      38              :   ///
      39              :   /// Note: String.fromEnvironment only works for compile-time constants that
      40              :   /// are in our [supportedEnvVars] set. This is a limitation of the Dart
      41              :   /// language when using --dart-define.
      42              :   ///
      43              :   /// @param key The name of the environment variable to retrieve
      44              :   /// @return The value of the environment variable, or null if not found
      45           73 :   @override
      46              :   String? getValue(String key) {
      47              :     // Priority 1: String.fromEnvironment (--dart-define values)
      48              :     // Only check if this is a known environment variable
      49              :     String? value;
      50           73 :     if (supportedEnvVars.contains(key)) {
      51           73 :       final fromEnvironment = getFromEnvironment(key);
      52           73 :       if (fromEnvironment != null && fromEnvironment.isNotEmpty) {
      53              :         value = fromEnvironment;
      54              :       }
      55              :     }
      56              : 
      57              :     // Priority 2: Platform environment variables
      58          146 :     value ??= io.Platform.environment[key];
      59              : 
      60              :     // Handle comma-separated values for --define compatibility
      61              :     // The --define flag cannot handle commas in values, so we use semicolons
      62              :     // as a delimiter for these specific variables and convert them back
      63              :     if (value != null) {
      64              :       switch (key) {
      65           73 :         case otelResourceAttributes:
      66           73 :         case otelPropagators:
      67           73 :         case otelExporterOtlpHeaders:
      68           73 :         case otelExporterOtlpTracesHeaders:
      69           73 :         case otelExporterOtlpMetricsHeaders:
      70           73 :         case otelExporterOtlpLogsHeaders:
      71            0 :           value = value.replaceAll(';', ',');
      72              :           break;
      73              :       }
      74              :     }
      75              : 
      76              :     return value;
      77              :   }
      78              : }