c# - 在 DotNet 中创建 AWS Cognito PreSignup Lambda

Question

使用 .Net Core 1.0 Lambda，我希望能够创建一个 Lambda 函数来处理来自 AWS Cognito 用户池的 PreSignUp 触发器。

using Amazon.Lambda.Core;

[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.Json.JsonSerializer))]

public class PreSignUp_SignUp
{
  public string userPoolId { get; set; }
  public const string EmailKey = "email";
  public const string PhoneNumber = "phone_number";
  public Dictionary<string,string> userAttributes { get; set; }
  public Dictionary<string, string> validationData { get; set; }
}

public class PreSignup_SignUpResponse
{
  public bool autoConfirmUser { get; set; }
}

public class Function
{
  public PreSignup_SignUpResponse FunctionHandler(PreSignUp_SignUp input, ILambdaContext context)
  {
      return new PreSignup_SignUpResponse { autoConfirmUser = true };
  }
}

虽然请求成功并在使用示例请求调用 Lambda 时返回响应:

{
  "datasetName": "datasetName",
  "eventType": "SyncTrigger",
  "region": "us-east-1",
  "identityId": "identityId",
  "datasetRecords": {
    "SampleKey2": {
      "newValue": "newValue2",
      "oldValue": "oldValue2",
      "op": "replace"
    },
    "SampleKey1": {
      "newValue": "newValue1",
      "oldValue": "oldValue1",
      "op": "replace"
    }
  },
  "identityPoolId": "identityPoolId",
  "version": 2
}

当通过 .Net AmazonCognitoIdentityProviderClient 执行实际注册时，我返回错误:

Amazon.CognitoIdentityProvider.Model.InvalidLambdaResponseException : Unrecognizable lambda output

我猜这意味着我没有得到正确的响应(甚至可能是请求)的形状。

有人有适用于 AWS Cognito 中的 PreSignUp 触发器的 .Net Lambda 函数示例吗？

Answer 1

Cognito 触发器请求/响应必须包含 Cognito 触发器文档中指定的整个有效负载:

http://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-identity-pools-working-with-aws-lambda-triggers.html

我发现在诊断这个问题时最好的起点是创建一个函数处理程序，它接受一个 JObject 然后记录并返回相同的对象，例如

public JObject FunctionHandler(JObject input, ILambdaContext context)
{
    context.Logger.LogLine("Input was: " + input);
    return input;
}

这会捕获 cloudwatch 日志中的有效负载，然后帮助您转向所需的强类型结构。

在我的 PreSignUp 案例中，我最终创建了以下类型来实现一个简单的功能，该功能可以自动验证所有提供的凭据。

public abstract class AbstractTriggerRequest
{
    [JsonProperty("userAttributes")]
    public Dictionary<string, string> UserAttributes { get; set; }
}

public abstract class AbstractTriggerResponse
{
}

public class TriggerCallerContext
{
    [JsonProperty("awsSdkVersion")]
    public string AwsSdkVersion { get; set; }
    [JsonProperty("clientId")]
    public string ClientId { get; set; }
}

public abstract class AbstractTriggerBase<TRequest, TResponse>
    where TRequest: AbstractTriggerRequest
    where TResponse: AbstractTriggerResponse
{
    [JsonProperty("version")]
    public int Version { get; set; }
    [JsonProperty("triggerSource")]
    public string TriggerSource { get; set; }
    [JsonProperty("region")]
    public string Region { get; set; }
    [JsonProperty("userPoolId")]
    public string UserPoolId { get; set; }  
    [JsonProperty("callerContext")]
    public TriggerCallerContext CallerContext { get; set; }
    [JsonProperty("request")]
    public TRequest Request { get; set; }
    [JsonProperty("response")]
    public TResponse Response { get; set; }
    [JsonProperty("userName", NullValueHandling = NullValueHandling.Ignore)]
    public string UserName { get; set; }
}

public class PreSignUpSignUpRequest : AbstractTriggerRequest
{
    [JsonProperty("validationData")]
    public Dictionary<string,string> ValidationData { get; set; }
}

Lambda 函数然后以以下签名结束:

public class Function
{
    public PreSignUp_SignUp FunctionHandler(PreSignUp_SignUp input, ILambdaContext context)
    {
        context.Logger.LogLine("Auto-confirming everything!");

        input.Response = new PreSignUpSignUpResponse {
            AutoConfirmUser = true,
            // you can only auto-verify email or phone if it's present in the user attributes
            AutoVerifyEmail = input.Request.UserAttributes.ContainsKey("email"),
            AutoVerifyPhone = input.Request.UserAttributes.ContainsKey("phone_number") 
        };

        return input;
    }
}

希望这可以帮助其他任何在为 Cognito 编写 Lambda 触发器时遇到问题的人。