Interface IKeyVaultService

Namespace: arolariu.Backend.Common.Services.KeyVault

Assembly: arolariu.Backend.Common.dll

Defines the contract for secure secret retrieval from Azure Key Vault or equivalent secure storage systems. This interface provides abstraction for accessing sensitive configuration data including connection strings, API keys, certificates, and other confidential information required by the application.

public interface IKeyVaultService

Examples

// Dependency injection registration
services.AddSingleton<IKeyVaultService, KeyVaultService>();

// Usage in application services
public class DatabaseService
{
    private readonly IKeyVaultService _keyVaultService;

    public DatabaseService(IKeyVaultService keyVaultService)
    {
        _keyVaultService = keyVaultService;
    }

    public async Task<IDbConnection> CreateConnectionAsync()
    {
        var connectionString = await _keyVaultService.TryGetSecretAsync("sql-connection-string");
        return new SqlConnection(connectionString);
    }
}

// Error handling example
try
{
    var apiKey = await keyVaultService.TryGetSecretAsync("external-api-key");
    // Use the API key
}
catch (KeyVaultException ex)
{
    // Handle secret retrieval failure
    logger.LogError(ex, "Failed to retrieve API key from Key Vault");
    throw new ConfigurationException("Required configuration unavailable", ex);
}

Remarks

The IKeyVaultService interface enables secure secret management across different deployment environments:

Cloud Deployments: - Integration with Azure Key Vault for production-grade secret storage - Managed Identity authentication for secure, credential-free access - Automatic secret rotation and versioning capabilities - Geo-redundant storage for high availability and disaster recovery

Development Environments: - Local secret storage using user secrets or configuration files - Environment variable fallbacks for development flexibility - Mock implementations for testing scenarios - Simplified authentication for local development workflows

Security Principles: The interface follows security best practices: - Secrets are never logged or exposed in error messages - All secret access is auditable and traceable - Failed secret retrieval should fail securely without exposing sensitive information - Implementations should support secret caching with appropriate expiration policies

Performance Considerations: - Asynchronous operations to prevent blocking I/O operations - Caching strategies to minimize external service calls - Retry policies for transient failures - Circuit breaker patterns for service resilience

Integration Patterns: This service is typically used by: - Configuration providers for loading connection strings and API keys - Authentication services for JWT signing keys and certificates - External service clients for API keys and authentication tokens - Data access layers for database connection strings

Methods

TryGetSecret(string)

Retrieves a secret from the secure storage system synchronously. This method blocks the calling thread until the secret is retrieved or an error occurs.

string TryGetSecret(string secretName)

Parameters

secretName string: The name or identifier of the secret to retrieve from the secure storage. Secret names should follow the naming conventions of the underlying storage system (e.g., Azure Key Vault naming rules: alphanumeric characters and hyphens only).

Returns

string: The value of the requested secret as a string. The returned value should never be null - implementations should throw exceptions for missing secrets.

Examples

// Basic synchronous usage
var connectionString = keyVaultService.TryGetSecret("database-connection");

// With error handling
try
{
    var jwtSecret = keyVaultService.TryGetSecret("jwt-signing-key");
    // Configure JWT authentication
}
catch (InvalidOperationException)
{
    // Handle missing secret
    throw new ConfigurationException("JWT signing key not configured");
}

Remarks

Synchronous Operation: This method provides synchronous access to secrets for scenarios where: - Secrets are needed during application startup - Legacy synchronous code requires secret access - Simple configuration loading scenarios

Performance Impact: - Blocks the calling thread until completion - May cause thread pool starvation in high-concurrency scenarios - Should be avoided in ASP.NET request processing pipelines - Consider using TryGetSecretAsync(string) for better performance

Caching Behavior: Implementations should implement appropriate caching to: - Minimize external service calls and network latency - Reduce costs associated with Key Vault operations - Improve application performance and responsiveness - Balance cache duration with security requirements

Error Handling: This method should handle various error scenarios: - Network connectivity issues with external secret stores - Authentication and authorization failures - Missing or deleted secrets - Service quota limitations and throttling

Exceptions

ArgumentNullException: Thrown when secretName is null or empty.
ArgumentException: Thrown when secretName contains invalid characters or format.
AuthenticationException: Thrown when the service lacks permissions to access the requested secret.
HttpRequestException: Thrown when network connectivity issues prevent secret retrieval.
InvalidOperationException: Thrown when the secret does not exist or has been deleted.

TryGetSecretAsync(string)

Retrieves a secret from the secure storage system asynchronously. This method provides non-blocking access to secrets, making it suitable for high-performance scenarios and modern asynchronous programming patterns.

Task<string> TryGetSecretAsync(string secretName)

Parameters

secretName string: The name or identifier of the secret to retrieve from the secure storage. Secret names should follow the naming conventions of the underlying storage system and should be validated before making the request to prevent unnecessary service calls.

Returns

Task<string>: A Task<TResult> representing the asynchronous secret retrieval operation. The task result contains the value of the requested secret as a string. The task may be faulted if secret retrieval fails due to authentication, network, or configuration issues.

Examples

// Basic asynchronous usage
var storageKey = await keyVaultService.TryGetSecretAsync("storage-account-key");

// Integration with configuration loading
public async Task<ApplicationOptions> LoadConfigurationAsync()
{
    var options = new ApplicationOptions();

    // Load multiple secrets concurrently
    var secretTasks = new[]
    {
        keyVaultService.TryGetSecretAsync("sql-connection"),
        keyVaultService.TryGetSecretAsync("cosmos-connection"),
        keyVaultService.TryGetSecretAsync("jwt-secret")
    };

    var secrets = await Task.WhenAll(secretTasks);

    options.SqlConnectionString = secrets[0];
    options.NoSqlConnectionString = secrets[1];
    options.JwtSecret = secrets[2];

    return options;
}

// Error handling with specific exception types
try
{
    var apiKey = await keyVaultService.TryGetSecretAsync("third-party-api-key");
    return new ExternalApiClient(apiKey);
}
catch (AuthenticationException ex)
{
    logger.LogError(ex, "Access denied to Key Vault secret");
    throw new ConfigurationException("Insufficient permissions for secret access");
}
catch (InvalidOperationException ex)
{
    logger.LogError(ex, "Secret not found in Key Vault");
    throw new ConfigurationException("Required API key not configured");
}

Remarks

Asynchronous Benefits: This method is recommended for production scenarios because it: - Prevents thread pool exhaustion in high-concurrency applications - Integrates seamlessly with ASP.NET Core request processing - Enables better resource utilization and application scalability - Supports cancellation and timeout scenarios through async patterns

Performance Optimization: Async secret retrieval enables: - Concurrent secret loading during application startup - Non-blocking I/O operations for better throughput - Integration with async middleware and service pipelines - Efficient resource utilization in containerized environments

Resilience Patterns: Implementations should support: - Retry policies with exponential backoff for transient failures - Circuit breaker patterns to prevent cascade failures - Timeout configuration to prevent hanging operations - Fallback mechanisms for service degradation scenarios

Security Considerations: - Secrets should be retrieved over encrypted connections (HTTPS/TLS) - Authentication tokens should be cached securely and refreshed automatically - Secret values should never appear in logs, traces, or error messages - Access patterns should be monitored for security auditing

Exceptions

ArgumentNullException: Thrown when secretName is null or empty.
ArgumentException: Thrown when secretName contains invalid characters or exceeds length limits.
AuthenticationException: Thrown when the application lacks sufficient permissions to access the requested secret.
HttpRequestException: Thrown when network connectivity issues prevent communication with the secret storage service.
InvalidOperationException: Thrown when the requested secret does not exist, has been deleted, or is in an invalid state.
OperationCanceledException: Thrown when the operation is cancelled due to timeout or explicit cancellation.

Table of Contents

Interface IKeyVaultService

Examples

Remarks

Methods

TryGetSecret(string)

Parameters

Returns

Examples

Remarks

Exceptions

TryGetSecretAsync(string)

Parameters

Returns

Examples

Remarks

Exceptions