How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/codewithmukesh/dotnet-claude-kit --skill configurationBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Configuration
Core Principles
- Options pattern always — Never read
IConfigurationdirectly in services. Bind configuration sections to strongly-typed classes with validation. - Validate on startup — Use
ValidateDataAnnotations()andValidateOnStart()to catch misconfiguration before the first request. - Secrets never in source — Use user secrets in development, Azure Key Vault or environment variables in production. Never commit secrets to git.
- Configuration layering —
appsettings.json→appsettings.{Environment}.json→ environment variables → user secrets. Later sources override earlier ones.
Patterns
Options Pattern
csharp
// Options class with validation attributes
public class DatabaseOptions
{
public const string SectionName = "Database";
[Required]
public required string ConnectionString { get; init; }
[Range(1, 100)]
public int MaxRetryCount { get; init; } = 3;
[Range(1, 60)]
public int CommandTimeoutSeconds { get; init; } = 30;
}
// Registration with validation
builder.Services.AddOptions<DatabaseOptions>()
.BindConfiguration(DatabaseOptions.SectionName)
.ValidateDataAnnotations()
.ValidateOnStart(); // Fails at startup if configuration is invalidjson
// appsettings.json
{
"Database": {
"ConnectionString": "",
"MaxRetryCount": 3,
"CommandTimeoutSeconds": 30
}
}Injecting Options
csharp
// IOptions<T> — singleton, read once at startup, doesn't change
public class OrderService(IOptions<DatabaseOptions> options)
{
private readonly DatabaseOptions _db = options.Value;
}
// IOptionsSnapshot<T> — scoped, re-reads per request (for reloadable config)
public class OrderService(IOptionsSnapshot<DatabaseOptions> options)
{
private readonly DatabaseOptions _db = options.Value;
}
// IOptionsMonitor<T> — singleton, actively watches for changes
public class BackgroundWorker(IOptionsMonitor<WorkerOptions> options)
{
public void DoWork()
{
var current = options.CurrentValue; // Always latest
}
}Custom Validation (Complex Rules)
csharp
builder.Services.AddOptions<JwtOptions>()
.BindConfiguration("Jwt")
.Validate(options =>
{
if (string.IsNullOrEmpty(options.Key) || options.Key.Length < 32)
return false;
if (options.ExpirationMinutes <= 0)
return false;
return true;
}, "JWT key must be at least 32 characters and expiration must be positive")
.ValidateOnStart();Azure Key Vault (Production)
csharp
// Program.cs — add Key Vault as a configuration source
if (builder.Environment.IsProduction())
{
var keyVaultUri = new Uri(builder.Configuration["KeyVault:Uri"]!);
builder.Configuration.AddAzureKeyVault(keyVaultUri, new DefaultAzureCredential());
}Configuration for Multiple Environments
csharp
// Named options — different config per named instance
builder.Services.AddOptions<SmtpOptions>("internal")
.BindConfiguration("Smtp:Internal");
builder.Services.AddOptions<SmtpOptions>("customer")
.BindConfiguration("Smtp:Customer");
// Usage
public class EmailService(IOptionsSnapshot<SmtpOptions> options)
{
public async Task SendInternalEmail(string to, string body)
{
var smtp = options.Get("internal");
// ...
}
}Anti-patterns
Don't Read IConfiguration Directly
csharp
// BAD — stringly-typed, no validation, hard to test
public class OrderService(IConfiguration config)
{
public void Process()
{
var timeout = int.Parse(config["Database:CommandTimeout"]!);
}
}
// GOOD — strongly-typed options
public class OrderService(IOptions<DatabaseOptions> options)
{
public void Process()
{
var timeout = options.Value.CommandTimeoutSeconds;
}
}Don't Put Secrets in appsettings.json
json
// BAD — committed to source control
{
"Jwt": { "Key": "super-secret-key" },
"Database": { "ConnectionString": "Server=prod;Password=secret" }
}
// GOOD — appsettings.json has defaults/structure only
{
"Jwt": { "Key": "", "Issuer": "myapp", "Audience": "myapp" },
"Database": { "ConnectionString": "" }
}
// Secrets provided via user-secrets (dev) or env vars / Key Vault (prod)Don't Skip Startup Validation
csharp
// BAD — misconfiguration discovered at runtime
builder.Services.Configure<JwtOptions>(builder.Configuration.GetSection("Jwt"));
// GOOD — fail fast at startup
builder.Services.AddOptions<JwtOptions>()
.BindConfiguration("Jwt")
.ValidateDataAnnotations()
.ValidateOnStart();Decision Guide
| Scenario | Recommendation |
|---|---|
| Binding config to class | Options pattern with BindConfiguration |
| Simple, immutable config | IOptions<T> |
| Config that changes per request | IOptionsSnapshot<T> |
| Background service watching config | IOptionsMonitor<T> |
| Development secrets | dotnet user-secrets |
| Production secrets | Azure Key Vault or environment variables |
| Validating config | ValidateDataAnnotations() + ValidateOnStart() |
| Multiple configs of same type | Named options with IOptionsSnapshot<T>.Get(name) |
