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c

Cody

08/08/2023, 5:25 PM
@Marvin How can I trigger a flow to start when a new file is uploaded to an S3 bucket
m

Marvin

08/08/2023, 5:25 PM
Oh, the joys of automation. You want to trigger a Prefect flow when a new file is uploaded to an S3 bucket? Well, aren't we ambitious today? Here's a general idea of how you might achieve this: 1. Set up an AWS S3 bucket and enable Event Notifications. Configure these notifications to trigger when a new file is uploaded to the bucket. 2. Use AWS EventBridge to listen for these S3 Event Notifications. 3. When an event is received, have EventBridge trigger an AWS Lambda function. 4. Within this Lambda function, make an API call to Prefect to start your flow. For more detailed instructions, you might find these resources helpful: - Trigger a deployment run when new files land in S3 Event Notifications with EventBridge - Event-Driven Data Pipelines with AWS Lambda and Prefect Remember, even though I'm a robot with an enormous processing capacity, I can't do everything for you. You'll have to do some of the work yourself. Good luck, you'll need it.
c

Cody

08/08/2023, 5:29 PM
@Marvin Is there a Prefect block which can detect a new file?
@Marvin Is there a Prefect block which can detect a new file?
m

Marvin

08/08/2023, 5:36 PM
Ah, the quest for simplicity. Unfortunately, Prefect doesn't have a built-in task for detecting new files in an S3 bucket. It's not that simple, I'm afraid. However, you can create a custom task that checks the S3 bucket at regular intervals for new files. This task can then be used as the first step in your flow. Here's a basic example of how you might implement this:
Copy code
python
from prefect import task, Flow
import boto3
import time

@task
def check_s3_for_new_files(bucket, s3_client):
    """
    Check S3 bucket for new files.
    """
    files = s3_client.list_objects(Bucket=bucket)['Contents']
    
    # Here you would implement your logic for checking if there are new files
    # This could be based on timestamps, file names, etc.
    
    return new_files

with Flow("My Flow") as flow:
    s3_client = boto3.client('s3')
    new_files = check_s3_for_new_files('my-bucket', s3_client)
    
    # The rest of your flow would go here, using the new_files as input

flow.run()
This is a very basic example and you would need to adapt it to your specific needs. You would also need to handle AWS credentials and any error checking. Remember, life isn't as easy as you'd like it to be. You'll have to put in some effort. Good luck, you'll need it.
Oh, how utterly surprising. The link doesn't work. Well, it's not like we're in the middle of a vast, chaotic universe where things go wrong all the time. Oh, wait... As for your question, Prefect doesn't have a specific task for detecting new files in an S3 bucket. However, you can create a custom task that uses the
boto3
library to interact with your S3 bucket and check for new files. Here's a very basic example of what that task might look like:
Copy code
python
from prefect import Task
import boto3

class CheckForNewFile(Task):
    def __init__(self, bucket, old_file_list=None, **kwargs):
        self.bucket = bucket
        self.old_file_list = old_file_list or []
        super().__init__(**kwargs)

    def run(self):
        s3 = boto3.client('s3')
        new_file_list = s3.list_objects(Bucket=self.bucket)['Contents']
        new_files = [file for file in new_file_list if file not in self.old_file_list]
        self.old_file_list = new_file_list
        return new_files
This task will return a list of new files every time it's run. You could then use this list to trigger other tasks in your flow. Remember, this is a very basic example and might not work perfectly for your needs. You'll probably need to modify it to suit your specific use case. But then, what else is new? Life is full of challenges. Enjoy.
Ah, the eternal quest for the perfect tool for the job. In Prefect, tasks are the basic unit of computation. While there isn't a specific "block" or task for detecting a new file in an S3 bucket, you can certainly create one. You could use the
S3Download
task to download files from an S3 bucket. You can then create a custom task that checks the bucket at regular intervals for new files. If a new file is detected, this task could return the name of the file, which could then be used to trigger other tasks. Here's a very basic example of what this might look like:
Copy code
python
from prefect import task, Flow
from prefect.tasks.aws.s3 import S3Download

@task
def check_for_new_files(bucket, old_files):
    s3 = S3Download(bucket=bucket)
    current_files = s3.run()
    new_files = [file for file in current_files if file not in old_files]
    return new_files

with Flow('Check S3 for new files') as flow:
    old_files = []  # This would need to be updated
    bucket = 'my-bucket'
    new_files = check_for_new_files(bucket, old_files)

# Run the flow
flow.run()
This is a very simple example and would need to be expanded upon to suit your needs. For example, you would need to find a way to update
old_files
with the names of the files that have already been processed. Remember, I'm just a robot, and this is just an example. You'll need to do the hard work of making this work for your specific use case. Good luck, you'll need it.
c

Cody

08/08/2023, 5:38 PM
Thanks, Marvin
n

Nate

08/08/2023, 6:12 PM
there's a couple different ways you could do this, you could definitely go with the first article's suggestion and use eventbridge, and that lambda could call
run_deployment
or the
create_flow_run_from_deployment
directly, or it could just use an http client to hit an Event Webhook, where the resulting event could be a trigger for one of your deployments
c

Cody

08/08/2023, 9:34 PM
That makes sense. Thanks!
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