AWS LambdaでCognitoユーザ一覧を取得 ref: https://qiita.com/kojiisd/items/690b5952835823ac1be1

file0.py

import json
from datetime import datetime
import os
import boto3

cognito_client = boto3.client('cognito-idp')

def list_users(event, context):

    if 'UserPoolId' not in event:
        raise KeyError("UserPoolId does not exist.")

    response = cognito_client.list_users(
        UserPoolId = event['UserPoolId']
    )

    return json.dumps(response, default=support_datetime_default)

def support_datetime_default(obj):
    if isinstance(obj, datetime):
        return obj.isoformat()
    raise TypeError(repr(obj) + " is not JSON serializable")

file1.txt

service: lambda-cognito-user-manager

provider:
  name: aws
  runtime: python3.6
  region: us-east-1
  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "cognito-idp:ListUsers"
      Resource: "arn:aws:cognito-idp:*"

functions:
  cognito-manager:
    handler: handler.list_users
    memorySize: 128
    timeout: 

file2.txt

{
  "UserPoolId": "us-east-1_XXXXXXXXXXX"
}

file3.txt

{
  "Users": [
    {
      "Username": "admin",
      "Attributes": [
        {
          "Name": "sub",
          "Value": "00000000-0000-0000-XXXX-XXXXXXXXXXXX"
        },
        {
          "Name": "email_verified",
          "Value": "false"
        },
        {
          "Name": "email",
          "Value": "xxxxxx@xxx.com"
        }
      ],
      "UserCreateDate": "2018-09-01T07:07:28.497000+00:00",
      "UserLastModifiedDate": "2018-09-01T07:09:20.934000+00:00",
      "Enabled": true,
      "UserStatus": "CONFIRMED"
    }
  ],
  "ResponseMetadata": {
    "RequestId": "XXXXXXXX-xxxx-xxxx-0000-XXXXXXXXXX",
    "HTTPStatusCode": 200,
    "HTTPHeaders": {
      "date": "Sun, 02 Sep 2018 08:37:00 GMT",
      "content-type": "application/x-amz-json-1.1",
      "content-length": "312",
      "connection": "keep-alive",
      "x-amzn-requestid": "XXXXXXXX-xxxx-xxxx-0000-XXXXXXXXXX"
    },
    "RetryAttempts": 0
  }
}