モノリシックな .NET REST API を AWS Lambdaに移行する

    [ApiController]
    [Route("[controller]")]
    public class BookingController : ControllerBase
    {
        private readonly ILogger<BookingController> _logger;
        private readonly IBookingRepository _bookingRepository;
        private readonly ICustomerService _customerService;

        public BookingController(ILogger<BookingController> logger,
            IBookingRepository bookingRepository,
            ICustomerService customerService)
        {
            this._logger = logger;
            this._bookingRepository = bookingRepository;
            this._customerService = customerService;
        }

        /// <summary>
        /// HTTP GET endpoint to list all bookings for a customer.
        /// </summary>
        /// <param name="customerId">The customer id to list for.</param>
        /// <returns>All <see cref="Booking"/> for the given customer.</returns>
        [HttpGet("customer/{customerId}")]
        public async Task<IActionResult> ListForCustomer(string customerId)
        {
            this._logger.LogInformation($"Received request to list bookings for {customerId}");

            return this.Ok(await this._bookingRepository.ListForCustomer(customerId));
        }
}

services.AddTransient<IBookingRepository, BookingRepository>();

public void ConfigureServices(IServiceCollection services)
{
	var databaseConnection =
		new DatabaseConnection(this.Configuration.GetConnectionString("DatabaseConnection"));
	
	services.AddSingleton<DatabaseConnection>(databaseConnection);
	
	services.AddDbContext<BookingContext>(options =>
		options.UseMySQL(databaseConnection.ToString()));

	services.AddTransient<IBookingRepository, BookingRepository>();
	services.AddHttpClient<ICustomerService, CustomerService>();
	
	services.AddControllers();
}

public static void ConfigureServices()
{
	var client = new AmazonSecretsManagerClient();
	
	var serviceCollection = new ServiceCollection();

	var connectionDetails = LoadDatabaseSecret(client);

	serviceCollection.AddDbContext<BookingContext>(options =>
		options.UseMySQL(connectionDetails.ToString()));
	
	serviceCollection.AddHttpClient<ICustomerService, CustomerService>();
	serviceCollection.AddTransient<IBookingRepository, BookingRepository>();
	serviceCollection.AddSingleton<DatabaseConnection>(connectionDetails);
	serviceCollection.AddSingleton<IConfiguration>(LoadAppConfiguration());

	serviceCollection.AddLogging(logging =>
	{
		logging.AddLambdaLogger();
		logging.SetMinimumLevel(LogLevel.Debug);
	});

	Services = serviceCollection.BuildServiceProvider();
}

public class Function
{
	private readonly IBookingRepository _bookingRepository;
	private readonly ILogger<Function> _logger;
	
	public Function()
	{
		ServerlessConfig.ConfigureServices();

		this._bookingRepository = ServerlessConfig.Services.GetRequiredService<IBookingRepository>();
		this._logger = ServerlessConfig.Services.GetRequiredService<ILogger<Function>>();
	}
	
	public async Task<APIGatewayProxyResponse> FunctionHandler(APIGatewayProxyRequest apigProxyEvent, ILambdaContext context)
	{
		if (!apigProxyEvent.PathParameters.ContainsKey("customerId"))
		{
			return new APIGatewayProxyResponse
			{
				StatusCode = 400,
				Headers = new Dictionary<string, string> { { "Content-Type", "application/json" } }
			};
		}

		var customerId = apigProxyEvent.PathParameters["customerId"];
		
		this._logger.LogInformation($"Received request to list bookings for: {customerId}");

		var customerBookings = await this._bookingRepository.ListForCustomer(customerId);
		
		return new APIGatewayProxyResponse
		{
			Body = JsonSerializer.Serialize(customerBookings),
			StatusCode = 200,
			Headers = new Dictionary<string, string> { { "Content-Type", "application/json" } }
		};
	}
}

Environment:
	Variables:
		SERVICE: bookings
		DATABASE_CONNECTION_SECRET_ID: !Ref SecretArn

var databaseConnectionSecret = client.GetSecretValueAsync(new GetSecretValueRequest()
            {
                SecretId = Environment.GetEnvironmentVariable("DATABASE_CONNECTION_SECRET_ID"),
            }).Result;

var parameter = new StringParameter(this, "dev-configuration", new StringParameterProps()
{
	ParameterName = "dotnet-to-lambda-dev",
	StringValue = "{\"CustomerApiEndpoint\": \"https://jsonplaceholder.typicode.com/users\"}",
	DataType = ParameterDataType.TEXT,
	Tier = ParameterTier.STANDARD,
	Type = ParameterType.STRING,
	Description = "Dev configuration for dotnet to lambda",
});

private static IConfiguration LoadAppConfiguration()
{
	var client = new AmazonSimpleSystemsManagementClient();
	var param = client.GetParameterAsync(new GetParameterRequest()
	{
		Name = "dotnet-to-lambda-dev"
	}).Result;
	
	return new ConfigurationBuilder()
		.AddJsonStream(new MemoryStream(Encoding.ASCII.GetBytes(param.Parameter.Value)))
		.Build();

private static DatabaseConnection LoadDatabaseSecret(AmazonSecretsManagerClient client)
{
	var databaseConnectionSecret = client.GetSecretValueAsync(new GetSecretValueRequest()
	{
		SecretId = Environment.GetEnvironmentVariable("DATABASE_CONNECTION_SECRET_ID"),
	}).Result;

	return JsonSerializer
		.Deserialize<DatabaseConnection>(databaseConnectionSecret.SecretString);
}

Policies:
	- AWSSecretsManagerGetSecretValuePolicy:
		SecretArn: !Ref SecretArn
	- SSMParameterReadPolicy:
		ParameterName: dotnet-to-lambda-dev

VpcConfig:
	SubnetIds:
	  - !Ref PrivateSubnet1
	  - !Ref PrivateSubnet2
	SecurityGroupIds:
	  - !Ref SecurityGroup

 PrivateSubnet1:
	Description: 'Required. Private subnet 1. Output from cdk deploy'
	Type: 'String'
PrivateSubnet2:
	Description: 'Required. Private subnet 2. Output from cdk deploy'
	Type: 'String'
SecurityGroup:
	Description: 'Required. Security group. Output from cdk deploy'
	Type: 'String'