AWS Lambda 查询 Redshift Serverless

在应用程序中，经常在Lambda 中调用redshift data api 去查询 redshift serverless 的数据，以下描述具体实现过程：

1：给Lambda 创建一个执行Lambda的IAM Role，并具有访问redshift serverless 权限，同时需要指定获取临时凭证的策略（参考：授予对 Amazon Redshift 数据 API 的访问权限）

因为在Lambda 执行的Role 将被转化为redshift serverless 对应的用户，加速role 名是：test-redshift-role，则对应的用户是：IAMR:test-redshift-role，下面是创建的测试IAM Role

 2：创建Lambda脚本，在脚本中使用redshift data api 访问redshift serverless：

import time
import traceback
import boto3
import logging
from collections import OrderedDict

print('boto3 version: ' + boto3.__version__)
logger = logging.getLogger()
logger.setLevel(logging.INFO)


def lambda_handler(event, context):
    # input parameters passed from the caller event
    # cluster identifier for the Amazon Redshift cluster
    redshift_workgroup_name = event['redshift_workgroup_name']
    # database name for the Amazon Redshift cluster
    redshift_database_name = event['redshift_database']
    # IAM Role of Amazon Redshift cluster having access to S3
    redshift_iam_role = event['redshift_iam_role']
    # run_type can be either asynchronous or synchronous; try tweaking based on your requirement
    run_type = event['run_type']

    
    sql_statements = OrderedDict()
    res = OrderedDict()

    if run_type != "synchronous" and run_type != "asynchronous":
        raise Exception(
            "Invalid Event run_type. \n run_type has to be synchronous or asynchronous.")

    isSynchronous = True if run_type == "synchronous" else False

    # initiate redshift-data redshift_data_api_client in boto3
    redshift_data_api_client = boto3.client('redshift-data')


    sql_statements['SELECT'] = "select top 10 * from \"taxlot\".\"public\".\"lot\" where accountnumber = '7LD701824' and cusip = '256219106';"
    
    logger.info("Running sql queries in {} mode!\n".format(run_type))

    try:
        for command, query in sql_statements.items():
            logging.info("Example of {} command :".format(command))
            res[command + " STATUS: "] = execute_sql_data_api(redshift_data_api_client, redshift_database_name, command, query,redshift_workgroup_name, isSynchronous)

    except Exception as e:
        raise Exception(str(e) + "\n" + traceback.format_exc())
    return res


def execute_sql_data_api(redshift_data_api_client, redshift_database_name, command, query, redshift_workgroup_name, isSynchronous):

    MAX_WAIT_CYCLES = 20
    attempts = 0
    # Calling Redshift Data API with executeStatement()
    res = redshift_data_api_client.execute_statement(Database=redshift_database_name,  Sql=query, WorkgroupName=redshift_workgroup_name)
    logger.info("Query result{}!\n".format(res))
    
    query_id = res["Id"]
    desc = redshift_data_api_client.describe_statement(Id=query_id)
    query_status = desc["Status"]
    logger.info("Query status: {} .... for query-->{}".format(query_status, query))
    logger.info("Query status: {} ".format(desc))    
    done = False

    # Wait until query is finished or max cycles limit has been reached.
    while not done and isSynchronous and attempts < MAX_WAIT_CYCLES:
        attempts += 1
        logger.info("Query cycle: {} ".format(attempts)) 
        time.sleep(1)
        desc = redshift_data_api_client.describe_statement(Id=query_id)
        query_status = desc["Status"]
        logger.info("Query status: {} ".format(query_status))  
        
        if query_status == "FAILED":
            raise Exception('SQL query failed:' +
                            query_id + ": " + desc["Error"])

        elif query_status == "FINISHED":
            logger.info("query status is: {} for query id: {} and command: {}".format(query_status, query_id, command))
            done = True
            # print result if there is a result (typically from Select statement)
            if desc['HasResultSet']:
                response = redshift_data_api_client.get_statement_result(Id=query_id)
                logger.info("Printing response of {} query --> {}".format(command, response['Records']))
        else:
            logger.info(
                "Current working... query status is: {} ".format(query_status))

    # Timeout Precaution
    if done == False and attempts >= MAX_WAIT_CYCLES and isSynchronous:
        logger.info("Limit for MAX_WAIT_CYCLES has been reached before the query was able to finish. We have exited out of the while-loop. You may increase the limit accordingly. \n")
        raise Exception("query status is: {} for query id: {} and command: {}".format(
            query_status, query_id, command))

    return query_status

测试时传入参数：

 至此，Lambda部分设置完，但在执行时将报权限拒绝错误，因为此时，Lambda 的执行Role：test-redshift-role 在数据库中对应的用户 IAMR:test-redshift-role 是没有访问权限的，所以需要在Redshift Serverless console中继续下面的第3步

"errorMessage": "SQL query failed:77d160f1-40ef-476b-bdc5-b5d64432e96d: ERROR: permission denied for relation lot\nTraceback (most recent call last):\n  File \"/var/task/lambda_function.py\", line 44

3：给IAM Role设置访问权限，此处是将用户加入到一个group中，并授予这个group访问全部表的select 权限，如下图所示

 或者直接赋予IAM Role 相应的权限

grant all on table "taxlot"."public"."lot" to "IAMR:test-redshift-role";

设置完后，再回到lambda，执行redshift serverless 查询成功。