如何在 python 中异步调用 aws 服务 aws lambda

Question

I need to call to async function inside lambda function. When executing this, it's showing this error

await wasn't used with future

Here is my code

async def main():
    bucketName = 'data-store-test'
    folder = 'Contacts-Aggre'
    lastModifiedFolderPath = await  getLastModifiedBucketPath(bucketName,folder)
    print('Received lastModifiedFolderPath:',lastModifiedFolderPath)
     
async def getLastModifiedBucketPath(bucketName, prefix):
    loop = asyncio.get_running_loop()
    bucket_objects = await asyncio.gather(*loop.run_in_executor(None, functools.partial(s3_client.list_objects_v2, Bucket=bucketName, Prefix=prefix)))
    all = bucket_objects['Contents']        
    latest = max(all, key=lambda x: x['LastModified'])
    folderPaths = latest['Key'].split('/')
    lastModifiedFolder = folderPaths[1] if len(folderPaths) >=2 else folderPaths[0]
    return lastModifiedFolder

def lambda_handler(event, context):
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

What is the issue in this code? I created another question also related to this. No one answered for me, that's why I created this.

In this getLastModifiedBucketPath method used to get specific bucket location last modified folder name. If I remove asyncio.gather part, then it's working. But I need to return value after it execute.

Answer 1

I'm just learning asyncio this week, so take this with a grain of salt, but my belief is:

• loop.run_in_executor returns a future
• This future is not awaited; when you try to splat it, you get the error (try out just that snippet in your REPL and you'll see)
• gather needs the splatted argument to be a list, not a future

Try awaiting that run_in_executor before using it as an argument to gather and see what happens.