无法通过API Gateway运行AWS Lambda函数 [英] Unable to run AWS Lambda function with API Gateway

问题描述

我创建了一个简单的python 3.7 lambda函数:

I have created a simple python 3.7 lambda function:

import json
import boto3

s3 = boto3.client("s3")


def lambda_handler(event, context):
    bucket = "nubi-data"
    key = "core/user.json"

    try:
        data = s3.get_object(Bucket=bucket, Key=key)
        json_data = data['Body'].read()

        #return json_data

        return {
            'statusCode': 200,
            "headers": {"Content-Type": "application/json"},
            'body': json.loads(json_data)
            }


    except Exception as e:
        print(e)
        raise e

此函数从s3存储桶读取json文件. json文件如下:

This function reads a json file from an s3 bucket. The json file looks like:

{"id":1，"name":"John"，"pwd":密码"}

{ "id": 1, "name": "John", "pwd": "password" }

当我在AWS控制台的功能编辑器屏幕中进行测试时，该功能成功运行，并显示以下输出:

The function runs successfully when I test from within function editor screen in AWS console with the following output:

响应:{"statusCode":200，"headers":{ "Content-Type":"application/json"}，"body":{ "id":1 "name":"John"， "pwd":密码"}}

Response: { "statusCode": 200, "headers": { "Content-Type": "application/json" }, "body": { "id": 1, "name": "John", "pwd": "password" } }

请求ID:"f57de02f-44dd-4854-9df9-9f3a8c90031d"

Request ID: "f57de02f-44dd-4854-9df9-9f3a8c90031d"

功能日志:START RequestId:f57de02f-44dd-4854-9df9-9f3a8c90031d 版本:$ LATEST END RequestId:f57de02f-44dd-4854-9df9-9f3a8c90031d 报告RequestId:f57de02f-44dd-4854-9df9-9f3a8c90031d持续时间: 260.70 ms计费时间:300 ms内存大小:128 MB使用的最大内存:84 MB

Function Logs: START RequestId: f57de02f-44dd-4854-9df9-9f3a8c90031d Version: $LATEST END RequestId: f57de02f-44dd-4854-9df9-9f3a8c90031d REPORT RequestId: f57de02f-44dd-4854-9df9-9f3a8c90031d Duration: 260.70 ms Billed Duration: 300 ms Memory Size: 128 MB Max Memory Used: 84 MB

但是当我从API网关测试功能时，出现错误消息

But when I test the function from the API Gateway, I get the error

UTC 2019年3月21日21:04:08:端点响应正文之前 转换:{"statusCode":200，"headers":{"Content-Type": "application/json"}，"body":{"id":1，1，"name":"John"，"pwd": "password"}}周三3月21日21:04:08 UTC:由于执行失败 配置错误:Lambda代理响应格式错误，3月21日，星期四 21:04:08 UTC 2019:方法完成，状态:502

Thu Mar 21 21:04:08 UTC 2019 : Endpoint response body before transformations: {"statusCode": 200, "headers": {"Content-Type": "application/json"}, "body": {"id": 1, "name": "John", "pwd": "password"}} Thu Mar 21 21:04:08 UTC 2019 : Execution failed due to configuration error: Malformed Lambda proxy response Thu Mar 21 21:04:08 UTC 2019 : Method completed with status: 502

推荐答案

更改

'body': json.loads(json_data)

到

'body': json.dumps(json_data)

API网关希望将字符串作为输出，而json.dumps正是这样做的.另一方面，json.loads从字符串中创建一个JSON.如果您知道NodeJS，它们分别相当于JSON.stringify和JSON.parse.

API Gateway expects a String as output and json.dumps does exactly this. json.loads, on the other hand, creates a JSON out of a String. If you know NodeJS, they're equivalent to JSON.stringify and JSON.parse, respectively.

示例

json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])

产生

'["foo"，{"bar":["baz"，null，1.0，2]}]'

'["foo", {"bar": ["baz", null, 1.0, 2]}]'

同时

json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]')

产生

[u'foo'，{u'bar':[u'baz'，None，1.0，2]}]

[u'foo', {u'bar': [u'baz', None, 1.0, 2]}]

此信息可在官方文档

编辑

OP和我都错过的另一件事是data['Body'].read()不会返回JSON本身，而​​是返回一个缓冲区.需要先将其解码.

One more thing both the OP and I missed is that data['Body'].read() doesn't return the JSON itself but a buffer instead. It needs to be decoded first.

json_data = data['Body'].read().decode('utf-8')将已经返回字符串化的JSON(当然，只是因为您的文件是JSON)，因此在return语句上，您应该能够像这样简单地做到这一点:

json_data = data['Body'].read().decode('utf-8') will return the stringified JSON already (just because your file is a JSON, of course), so on your return statement you should be able to simply do it like this:

return {
         'statusCode': 200,
         "headers": {"Content-Type": "application/json"},
         'body': json_data
     }

这篇关于无法通过API Gateway运行AWS Lambda函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！