Bedrock Agent无法解析Node.js Lambda响应，报DependencyFailedException求助

我有一个Bedrock Agent，其动作组已连接到Node.js Lambda并定义了API Schema。尽管已确保Lambda响应符合AWS官方文档规范，但调用端点时仍出现以下错误：

ERROR  DependencyFailedException: The server encountered an error processing the Lambda response. Check the Lambda response and retry the request

Lambda返回内容如下：

{
    "messageVersion": "1.0",
    "response": {
        "actionGroup": "downstream-actions",
        "apiPath": "/hello",
        "httpMethod": "GET",
        "httpStatusCode": 200,
        "responseBody": {
            "application/json": {
                "body": "{\"message\":\"Hello, world!\"}"
            }
        }
    }
}

该Lambda基于Node.js开发，我尝试将整个对象序列化后返回，但仍得到相同错误。

补充的API Schema：

{
  "openapi": "3.0.0",
  "info": {
    "title": "Downstream Action API",
    "version": "1.0.0",
    "description": "API for invoking downstream actions",
  },
  "paths": {
    "/hello": {
      "get": {
        "summary": "Get a hello world message",
        "description": "Simple endpoint that returns a hello world message",
        "operationId": "getHello",
        "responses": {
          "200": {
            "description": "Successful response",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "message": {
                      "type": "string",
                    },
                  },
                },
              },
            },
          },
        },
      },
    },
  },
}

• 修正responseBody的body格式：当前返回的body是序列化后的JSON字符串，但Bedrock Agent要求直接传入JSON对象，无需提前序列化。修改后的responseBody应如下：

  "responseBody": {
      "application/json": {
          "body": {"message":"Hello, world!"}
      }
  }
  

• 修复API Schema的语法错误：Schema中存在两处多余的尾逗号（info.description末尾、properties.message末尾），JSON不允许这种格式，会导致Bedrock解析失败。修正后的Schema：

  {
    "openapi": "3.0.0",
    "info": {
      "title": "Downstream Action API",
      "version": "1.0.0",
      "description": "API for invoking downstream actions"
    },
    "paths": {
      "/hello": {
        "get": {
          "summary": "Get a hello world message",
          "description": "Simple endpoint that returns a hello world message",
          "operationId": "getHello",
          "responses": {
            "200": {
              "description": "Successful response",
              "content": {
                "application/json": {
                  "schema": {
                    "type": "object",
                    "properties": {
                      "message": {
                        "type": "string"
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  

• 调整Node.js Lambda返回逻辑：Lambda会自动将返回的对象序列化为JSON，无需手动调用JSON.stringify()。直接返回对象即可避免双重序列化问题：

  exports.handler = async (event) => {
    return {
        "messageVersion": "1.0",
        "response": {
            "actionGroup": "downstream-actions",
            "apiPath": "/hello",
            "httpMethod": "GET",
            "httpStatusCode": 200,
            "responseBody": {
                "application/json": {
                    "body": {"message":"Hello, world!"}
                }
            }
        }
    };
  };
  

内容的提问来源于stack exchange，提问作者Haskell