Skip to content

Configuration in ConnectSoft Microservice Template

Purpose & Overview

Configuration is a fundamental aspect of any microservice, enabling applications to adapt to different environments, deployment contexts, and runtime requirements. In the ConnectSoft Microservice Template, configuration is managed through ASP.NET Core's extensible configuration model, enhanced with:

  • Options Pattern: Strongly-typed, validated configuration classes
  • Environment Awareness: Support for environment-specific overrides
  • Fail-Fast Validation: Startup-time validation to prevent misconfigured deployments
  • Azure App Configuration: Optional centralized configuration management
  • Dynamic Refresh: Runtime configuration updates without redeployment

The template treats configuration as code—structured, versioned, validated, and testable.

Configuration Philosophy

Configuration is the foundation for microservice correctness. All settings are strongly typed, validated at startup, and managed through a consistent options pattern. This ensures services fail fast on misconfiguration rather than operating with undefined behavior.

Architecture Overview

Configuration Sources Hierarchy

Command-Line Arguments (Highest Priority)
    ↓
Environment Variables
    ↓
Azure App Configuration (if enabled)
    ↓
appsettings.{Environment}.json
    ↓
appsettings.json (Base)
    ↓
IConfiguration (Lowest Priority)

Configuration Flow

Configuration Sources
    ↓
IConfigurationBuilder (Program.cs)
    ├── appsettings.json
    ├── appsettings.{Environment}.json
    ├── Azure App Configuration (optional)
    ├── Environment Variables
    └── Command-Line Args
    ↓
IConfiguration
    ↓
Options Pattern
    ├── Bind to POCOs
    ├── Validate with DataAnnotations
    ├── Validate with IValidateOptions<T>
    └── Register with IOptions<T>
    ↓
Dependency Injection
    └── Consumed by Services

Configuration Sources

appsettings.json (Base Configuration)

The base configuration file contains default values shared across all environments:

{
  "Microservice": {
    "MicroserviceName": "ConnectSoft.MicroserviceTemplate",
    "StartupWarmupSeconds": 20
  },
  "Validation": {
    "EnableClassLevelFailFast": true,
    "EnableRuleLevelFailFast": true
  }
}

Characteristics: - Loaded for all environments - Contains non-sensitive default values - Can be overridden by environment-specific files - Required file (not optional)

Environment-Specific Files

Environment-specific configuration files override base settings:

  • appsettings.Development.json: Local development overrides
  • appsettings.Docker.json: Container-specific settings
  • appsettings.Production.json: Production overrides (if needed)

Example (appsettings.Development.json):

{
  "Microservice": {
    "MicroserviceName": "ConnectSoft.MicroserviceTemplate.Dev"
  },
  "Serilog": {
    "MinimumLevel": {
      "Default": "Debug"
    }
  }
}

Selection Logic: The environment is determined by: - ASPNETCORE_ENVIRONMENT environment variable - DOTNET_ENVIRONMENT environment variable (alternative) - Falls back to Production if not set

Environment Variables

Environment variables can override any configuration value:

# Override using double underscore notation
export Microservice__MicroserviceName="MyService"
export Microservice__StartupWarmupSeconds="30"

# Or using colon notation
export Microservice:MicroserviceName="MyService"

Use Cases: - Container deployments (Docker, Kubernetes) - CI/CD pipelines - Local development overrides - Secrets injection (via Key Vault references)

Command-Line Arguments

Command-line arguments provide the highest priority overrides:

dotnet run --Microservice:MicroserviceName="TestService" --Microservice:StartupWarmupSeconds="10"

Azure App Configuration (Optional)

Azure App Configuration provides centralized, dynamic configuration:

configurationBuilder.AddAzureAppConfiguration(options =>
{
    options.Connect(connectionString)
        .Select("ConnectSoft.MicroserviceTemplate:*", LabelFilter.Null)
        .ConfigureRefresh(refresh =>
        {
            refresh.Register("ConnectSoft.MicroserviceTemplate:Settings:Sentinel", refreshAll: true);
            refresh.SetRefreshInterval(TimeSpan.FromMinutes(30));
        });
});

Features: - Centralized key-value storage - Dynamic refresh without redeployment - Environment labels for multi-environment support - Feature flags integration - Key Vault references for secrets

See Feature Flags for Azure App Configuration feature flags details.

Configuration Loading

Program.cs Configuration Setup

Configuration is loaded in DefineConfiguration:

// Program.cs
private static void DefineConfiguration(
    string[] args, 
    HostBuilderContext hostBuilderContext, 
    IConfigurationBuilder configurationBuilder)
{
    configurationBuilder.Sources.Clear();
    configurationBuilder
        .SetBasePath(hostBuilderContext.HostingEnvironment.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
        .AddJsonFile(
            $"appsettings.{hostBuilderContext.HostingEnvironment.EnvironmentName}.json",
            optional: true,
            reloadOnChange: true);

#if UseAzureAppConfigurationAsAdditionalConfigurationProvider
    IConfigurationRoot configurationRoot = configurationBuilder.Build();

    configurationBuilder.AddAzureAppConfiguration(options =>
    {
        string? connectionString = configurationRoot.GetConnectionString("AzureAppConfiguration");
        options.Connect(connectionString)
            .Select("ConnectSoft.MicroserviceTemplate:*", LabelFilter.Null)
            .ConfigureRefresh(refresh =>
            {
                refresh.Register("ConnectSoft.MicroserviceTemplate:Settings:Sentinel", refreshAll: true);
                refresh.SetRefreshInterval(TimeSpan.FromMinutes(30));
            })
            .ConfigureClientOptions(options =>
            {
                options.Retry.MaxRetries = 1;
            });
#if UseAzureAppConfigurationAsFeatureFlagsProvider
        options.UseFeatureFlags(featureFlagsOptions =>
        {
            featureFlagsOptions.Select("ConnectSoft.MicroserviceTemplate:*", LabelFilter.Null);
            featureFlagsOptions.SetRefreshInterval(TimeSpan.FromMinutes(30));
        });
#endif
    });
#endif

    configurationBuilder
        .AddEnvironmentVariables()
        .AddCommandLine(args);
}

Key Points: - Sources.Clear(): Removes default providers to ensure explicit ordering - reloadOnChange: true: Enables file-based configuration reloading - Environment-specific files are optional - Azure App Configuration is conditionally included

Configuration Precedence

Configuration sources are loaded in priority order (last wins):

Priority Source Override Capability
Highest Command-Line Arguments Overrides everything
Environment Variables Overrides files and Azure
Azure App Configuration Overrides file-based config
appsettings.{Environment}.json Overrides base file
Lowest appsettings.json Base defaults

Options Pattern

Purpose

The Options Pattern provides: - Strong Typing: Configuration bound to POCO classes - Validation: Startup-time validation of required values - IntelliSense: IDE support for configuration properties - Refactoring Safety: Compile-time checking of configuration usage - Testability: Easy to mock and override in tests

Options Class Definition

Options classes are simple POCOs with DataAnnotations:

// MicroserviceOptions.cs
namespace ConnectSoft.MicroserviceTemplate.Options
{
    using System.ComponentModel.DataAnnotations;

    public sealed class MicroserviceOptions
    {
        public const string MicroserviceOptionsSectionName = "Microservice";

        [Required]
        required public string MicroserviceName { get; set; }

        [Required]
        [Range(0, int.MaxValue, ErrorMessage = "StartupWarmupSeconds must be 0 or positive.")]
        required public int StartupWarmupSeconds { get; set; } = 20;
    }
}

Characteristics: - sealed: Prevents inheritance - [Required]: Validates property is not null/empty - [Range]: Validates numeric ranges - Section name constant for consistency - Default values where appropriate

Options Validator

Options are validated using source-generated validators:

// ValidateMicroserviceOptions.cs
namespace ConnectSoft.MicroserviceTemplate.Options
{
    using Microsoft.Extensions.Options;

    /// <summary>
    /// Source-generated validator for MicroserviceOptions.
    /// </summary>
    [OptionsValidator]
    public partial class ValidateMicroserviceOptions : IValidateOptions<MicroserviceOptions>
    {
    }
}

The [OptionsValidator] attribute instructs the Roslyn source generator to: - Generate validation logic based on DataAnnotations - Implement IValidateOptions<TOptions> - Validate nested objects with [ValidateObjectMembers] (if needed)

Options Registration

Options are registered in OptionsExtensions.cs:

// OptionsExtensions.cs
private static TOptions AddCustomOptions<TOptions, TOptionsValidator>(
    IServiceCollection services, 
    IConfiguration configuration, 
    string sectionName)
    where TOptions : class
    where TOptionsValidator : class, IValidateOptions<TOptions>, new()
{
    var configurationSection = configuration.GetSection(sectionName);
    string optionsPath = configurationSection.Path;

    services
        .AddOptions<TOptions>()
        .BindConfiguration(optionsPath, options =>
        {
            options.ErrorOnUnknownConfiguration = true; // Strict binding
        })
        .ValidateDataAnnotations()  // Validate DataAnnotations
        .ValidateOnStart();  // Fail-fast validation

    // Register custom validator
    services.AddSingleton<IValidateOptions<TOptions>, TOptionsValidator>();
    services.ActivateSingleton<IValidateOptions<TOptions>>();

    // Validate immediately and throw if invalid
    var options = configurationSection.Get<TOptions>() 
        ?? throw new ArgumentException($"Failed to bind section '{sectionName}'.");

    var validator = new TOptionsValidator();
    var result = validator.Validate(string.Empty, options);
    if (result.Failed)
    {
        throw new OptionsValidationException(
            sectionName, 
            typeof(TOptions), 
            result.Failures);
    }

    return options;
}

Key Features: - ErrorOnUnknownConfiguration: Fails if config contains unknown properties - ValidateDataAnnotations(): Validates [Required], [Range], etc. - ValidateOnStart(): Ensures validation occurs during startup - Immediate validation: Throws exception if configuration is invalid

Using Options in Services

Options are injected via dependency injection:

public class MyService
{
    private readonly MicroserviceOptions options;

    public MyService(IOptions<MicroserviceOptions> options)
    {
        this.options = options.Value 
            ?? throw new ArgumentNullException(nameof(options));
    }

    public string GetServiceName() => this.options.MicroserviceName;
}

Options Interface Types:

Interface Lifetime Use Case
IOptions<T> Singleton Immutable config, loaded once at startup
IOptionsSnapshot<T> Scoped Per-request config (supports reload)
IOptionsMonitor<T> Singleton Monitors config changes, supports reload

Example with IOptionsMonitor (for dynamic config):

public class DynamicService
{
    private readonly IOptionsMonitor<MicroserviceOptions> optionsMonitor;

    public DynamicService(IOptionsMonitor<MicroserviceOptions> optionsMonitor)
    {
        this.optionsMonitor = optionsMonitor;

        // Subscribe to changes
        this.optionsMonitor.OnChange(options =>
        {
            this.logger.LogInformation("Configuration changed: {Name}", options.MicroserviceName);
        });
    }

    public string GetCurrentName() => this.optionsMonitor.CurrentValue.MicroserviceName;
}

Complex Configuration Structures

Nested Objects

Configuration can contain nested objects:

{
  "Orleans": {
    "OrleansEndpoints": {
      "SiloPort": 11111,
      "GatewayPort": 30000
    },
    "Connection": {
      "ConnectionString": "..."
    }
  }
}

Options class:

public sealed class OrleansOptions
{
    public const string OrleansOptionsSectionName = "Orleans";

    [Required]
    [ValidateObjectMembers]  // Validates nested object
    required public OrleansEndpointsOptions OrleansEndpoints { get; set; }

    [Required]
    [ValidateObjectMembers]
    required public OrleansConnectionOptions Connection { get; set; }
}

public sealed class OrleansEndpointsOptions
{
    [Required]
    [Range(1024, 65535)]
    required public int SiloPort { get; set; }

    [Required]
    [Range(1024, 65535)]
    required public int GatewayPort { get; set; }
}

Arrays and Lists

Arrays are bound automatically:

{
  "SupportedCultures": ["en-US", "fr-FR", "es-ES"]
}

public sealed class LocalizationOptions
{
    [Required]
    [MinLength(1)]
    required public List<string> SupportedCultures { get; set; }
}

Validation

DataAnnotations Validation

Standard DataAnnotations attributes are supported:

Attribute Purpose Example
[Required] Ensures property is not null/empty [Required] public string Name { get; set; }
[Range] Validates numeric range [Range(0, 100)] public int Percentage { get; set; }
[StringLength] Validates string length [StringLength(100)] public string Description { get; set; }
[Url] Validates URL format [Url] public string Endpoint { get; set; }
[EmailAddress] Validates email format [EmailAddress] public string Email { get; set; }
[ValidateObjectMembers] Validates nested objects [ValidateObjectMembers] public NestedOptions Nested { get; set; }

Custom Validation

For complex validation logic, implement IValidateOptions<T>:

public class CustomValidator : IValidateOptions<MyOptions>
{
    public ValidateOptionsResult Validate(string name, MyOptions options)
    {
        var failures = new List<string>();

        if (options.StartDate >= options.EndDate)
        {
            failures.Add("StartDate must be before EndDate.");
        }

        if (failures.Count > 0)
        {
            return ValidateOptionsResult.Fail(failures);
        }

        return ValidateOptionsResult.Success;
    }
}

Register custom validator:

services.AddSingleton<IValidateOptions<MyOptions>, CustomValidator>();

Fail-Fast Validation

All options are validated at startup via .ValidateOnStart():

Benefits: - Prevents misconfigured services from starting - Clear error messages at startup - No runtime surprises - Easier debugging

Example Failure:

If MicroserviceName is missing:

System.InvalidOperationException: Failed to validate options: MicroserviceOptions
The MicroserviceName field is required.

The application will not start, preventing undefined behavior.

Azure App Configuration Integration

Azure App Configuration provides centralized, dynamic configuration management. When enabled, it serves as an additional configuration provider that overrides file-based configuration.

Overview

Azure App Configuration offers: - Centralized Management: Single source of truth for configuration across services - Dynamic Updates: Change configuration without redeployment - Environment Labels: Multi-environment configuration support - Feature Flags: Built-in feature flag management - Key Vault Integration: Secure secret management

See Azure App Configuration for comprehensive documentation.

Quick Setup

Azure App Configuration is conditionally integrated:

#if UseAzureAppConfigurationAsAdditionalConfigurationProvider
configurationBuilder.AddAzureAppConfiguration(options =>
{
    string? connectionString = configurationRoot.GetConnectionString("AzureAppConfiguration");
    options.Connect(connectionString)
        // Select keys matching pattern
        .Select("ConnectSoft.MicroserviceTemplate:*", LabelFilter.Null)

        // Configure refresh
        .ConfigureRefresh(refresh =>
        {
            refresh.Register("ConnectSoft.MicroserviceTemplate:Settings:Sentinel", refreshAll: true);
            refresh.SetRefreshInterval(TimeSpan.FromMinutes(30));
        })

        // Configure retry
        .ConfigureClientOptions(options =>
        {
            options.Retry.MaxRetries = 1;
        });

    // Feature flags (optional)
#if UseAzureAppConfigurationAsFeatureFlagsProvider
    options.UseFeatureFlags(featureFlagsOptions =>
    {
        featureFlagsOptions.Select("ConnectSoft.MicroserviceTemplate:*", LabelFilter.Null);
        featureFlagsOptions.SetRefreshInterval(TimeSpan.FromMinutes(30));
    });
#endif
});
#endif

Configuration Priority

Azure App Configuration sits in the configuration hierarchy as follows:

Command-Line Arguments (Highest Priority)
    ↓
Environment Variables
    ↓
Azure App Configuration (if enabled)
    ↓
appsettings.{Environment}.json
    ↓
appsettings.json (Base)

Dynamic Configuration with IOptionsMonitor

Use IOptionsMonitor<T> to access dynamically refreshing configuration:

public class ConfigurableService
{
    private readonly IOptionsMonitor<DynamicOptions> optionsMonitor;

    public ConfigurableService(IOptionsMonitor<DynamicOptions> optionsMonitor)
    {
        this.optionsMonitor = optionsMonitor;

        // Subscribe to changes
        this.optionsMonitor.OnChange(options =>
        {
            this.logger.LogInformation("Configuration updated at {Time}", DateTime.UtcNow);
        });
    }

    public void Process()
    {
        // Always gets latest value (even after refresh)
        var currentConfig = this.optionsMonitor.CurrentValue;
        // ... use config
    }
}

Middleware for Dynamic Refresh

Enable dynamic refresh middleware in the pipeline:

#if UseAzureAppConfigurationAsAdditionalConfigurationProvider
application.UseMicroserviceAzureAppConfiguration();
#endif

This middleware: - Polls for sentinel key changes at configured interval - Refreshes configuration when sentinel key changes - Updates IOptionsMonitor<T> instances automatically - Triggers change notifications for subscribers

For detailed information on Azure App Configuration, including: - Connection string configuration - Key selection and naming conventions - Environment labels and multi-environment support - Sentinel key strategy - Feature flags integration - Security considerations - Troubleshooting

See the Azure App Configuration documentation.

Testing

Unit Testing with In-Memory Configuration

Override configuration in tests:

[TestMethod]
public void Service_WithCustomConfig_ShouldWork()
{
    // Arrange
    var config = new ConfigurationBuilder()
        .AddInMemoryCollection(new Dictionary<string, string?>
        {
            ["Microservice:MicroserviceName"] = "TestService",
            ["Microservice:StartupWarmupSeconds"] = "0"
        })
        .Build();

    var services = new ServiceCollection();
    services.AddMicroserviceOptions<MicroserviceOptions>(config, "Microservice");
    services.AddScoped<MyService>();

    var provider = services.BuildServiceProvider();

    // Act
    var service = provider.GetRequiredService<MyService>();

    // Assert
    Assert.AreEqual("TestService", service.GetServiceName());
}

Testing Validation Failures

Verify validation behavior:

[TestMethod]
public void InvalidOptions_ShouldThrowAtStartup()
{
    // Arrange
    var config = new ConfigurationBuilder()
        .AddInMemoryCollection(new Dictionary<string, string?>
        {
            // Missing required MicroserviceName
            ["Microservice:StartupWarmupSeconds"] = "20"
        })
        .Build();

    var services = new ServiceCollection();
    services.AddMicroserviceOptions<MicroserviceOptions>(config, "Microservice");

    // Act & Assert
    Assert.ThrowsException<OptionsValidationException>(() =>
    {
        services.BuildServiceProvider().GetRequiredService<IOptions<MicroserviceOptions>>();
    });
}

Integration Testing

Use WebApplicationFactory with configuration overrides:

public class MyServiceTests
{
    [TestMethod]
    public async Task GetServiceName_ShouldReturnConfiguredName()
    {
        // Arrange
        var factory = new WebApplicationFactory<Program>()
            .WithWebHostBuilder(builder =>
            {
                builder.ConfigureAppConfiguration((context, config) =>
                {
                    config.AddInMemoryCollection(new Dictionary<string, string>
                    {
                        ["Microservice:MicroserviceName"] = "TestService"
                    });
                });
            });

        var client = factory.CreateClient();

        // Act
        var response = await client.GetAsync("/api/service/name");

        // Assert
        response.EnsureSuccessStatusCode();
    }
}

Best Practices

Do's

  1. Use Options Pattern for All Configuration 

    // ✅ GOOD - Strongly typed, validated
public class MyService(IOptions<MyOptions> options)

// ❌ BAD - Magic strings, no validation
public class MyService(IConfiguration config)
{
    var name = config["MyService:Name"]; // Error-prone
}

  2. Validate at Startup 

    // ✅ GOOD - Fail fast
.ValidateOnStart()

// ❌ BAD - Discover errors at runtime
// No validation

  3. Use Descriptive Section Names 

    // ✅ GOOD
public const string SectionName = "Microservice";

// ❌ BAD
public const string SectionName = "Config";

  4. Provide Sensible Defaults 

    // ✅ GOOD
required public int StartupWarmupSeconds { get; set; } = 20;

// ❌ BAD
required public int StartupWarmupSeconds { get; set; }  // Must always configure

  5. Document Configuration Properties 

    /// <summary>
/// Gets or sets the mandatory startup grace period, in seconds.
/// A value of 0 disables the grace window (useful for tests).
/// </summary>
[Required]
[Range(0, int.MaxValue)]
required public int StartupWarmupSeconds { get; set; } = 20;

  6. Separate Secrets from Configuration 

    // ✅ GOOD - Secrets in environment variables or Key Vault
{
  "Database": {
    "Server": "db.example.com"
    // ConnectionString injected via env var
  }
}

// ❌ BAD - Secrets in source control
{
  "Database": {
    "ConnectionString": "Server=db;Password=Secret123!"
  }
}

Don'ts

  1. Don't Use Magic Strings 

    // ❌ BAD
var name = configuration["Microservice:MicroserviceName"];

// ✅ GOOD
var name = options.Value.MicroserviceName;

  2. Don't Skip Validation 

    // ❌ BAD - No validation
services.AddOptions<MyOptions>()
    .Bind(configuration.GetSection("MyOptions"));

// ✅ GOOD - Validated
services.AddOptions<MyOptions>()
    .Bind(configuration.GetSection("MyOptions"))
    .ValidateDataAnnotations()
    .ValidateOnStart();

  3. Don't Store Secrets in Files 

    // ❌ BAD - Never commit secrets
{
  "ApiKey": "sk-1234567890abcdef"
}

// ✅ GOOD - Use Key Vault or environment variables
{
  "ApiKey": "@Microsoft.KeyVault(SecretUri=...)"
}

  4. Don't Use IConfiguration Directly in Business Logic 

    // ❌ BAD - Couples business logic to configuration format
public void Process()
{
    var threshold = int.Parse(configuration["Processing:Threshold"]);
}

// ✅ GOOD - Inject options
public void Process(IOptions<ProcessingOptions> options)
{
    var threshold = options.Value.Threshold;
}

  5. Don't Forget Environment-Specific Overrides 

    // ✅ GOOD - Environment-aware
// appsettings.json (base)
{ "LogLevel": "Information" }

// appsettings.Development.json (override)
{ "LogLevel": "Debug" }

Common Configuration Patterns

Connection Strings

Connection strings are managed separately:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=localhost;Database=MyDb;...",
    "AzureAppConfiguration": "Endpoint=https://..."
  }
}

Access via: 

var connectionString = configuration.GetConnectionString("DefaultConnection");

Feature Flags

Feature flags configuration (see Feature Flags):

{
  "FeatureManagement": {
    "Expose Features Api": true,
    "UseSemanticKernel": false
  }
}

Logging Configuration

Serilog configuration:

{
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "System": "Warning"
      }
    },
    "WriteTo": [
      { "Name": "Console" },
      { 
        "Name": "Seq",
        "Args": {
          "serverUrl": "http://localhost:5341"
        }
      }
    ]
  }
}

Troubleshooting

Issue: Configuration Not Loading

Symptoms: Options are null or default values.

Solutions: 1. Verify section name matches exactly (case-sensitive) 2. Check configuration file is in correct location 3. Verify appsettings.json is marked as "Copy to Output Directory" 4. Check environment variable is set correctly

Issue: Validation Failures at Startup

Symptoms: OptionsValidationException during startup.

Solutions: 1. Check error message for missing required properties 2. Verify [Required] attributes match actual requirements 3. Ensure environment-specific files override base correctly 4. Check DataAnnotations (Range, StringLength, etc.)

Issue: Azure App Configuration Not Refreshing

Symptoms: Configuration changes in Azure don't reflect in app.

Solutions: 1. Verify UseMicroserviceAzureAppConfiguration() middleware is registered 2. Check sentinel key is being updated 3. Verify refresh interval is appropriate 4. Check connection string is valid 5. Review logs for refresh errors

Issue: Environment-Specific Override Not Applied

Symptoms: Base config values used instead of environment-specific.

Solutions: 1. Verify ASPNETCORE_ENVIRONMENT or DOTNET_ENVIRONMENT is set 2. Check environment file name matches: appsettings.{Environment}.json 3. Verify file is optional but loaded (check logs) 4. Check environment variable casing (case-insensitive)

Summary

Configuration in the ConnectSoft Microservice Template provides:

  • ✅ Strong Typing: Options Pattern with POCO classes
  • ✅ Validation: Startup-time validation with DataAnnotations and custom validators
  • ✅ Environment Awareness: Layered configuration with environment-specific overrides
  • ✅ Fail-Fast: Services won't start with invalid configuration
  • ✅ Centralized Management: Azure App Configuration integration for cloud deployments
  • ✅ Dynamic Refresh: Runtime configuration updates without redeployment
  • ✅ Type Safety: IntelliSense support and compile-time checking
  • ✅ Testability: Easy to override in unit and integration tests

By following these patterns, teams can:

  • Deploy Safely: Validate configuration before service starts
  • Maintain Consistently: Strong typing prevents configuration drift
  • Adapt Easily: Environment-specific overrides for different deployment contexts
  • Scale Confidently: Centralized configuration for multi-service deployments
  • Debug Quickly: Clear validation errors at startup

Configuration is the foundation that enables microservices to operate correctly across diverse environments while maintaining safety, consistency, and observability.