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<@ULVA73B9P> I am running Prefect self-hosted, I w...
# ask-marvin
b
@Marvin I am running Prefect self-hosted, I want to trigger a deployment or flow when a file is uploaded to AWS S3, how can I do this?
m
✅ thought for 42.1 seconds
Let me provide you with a solution for triggering Prefect flows when files are uploaded to S3. There are two main approaches you can use: 1. Using AWS Lambda with Prefect API: - Create an AWS Lambda function that triggers when files are uploaded to your S3 bucket - The Lambda function can then call your Prefect deployment using the Prefect API - This gives you the most control and is a common pattern Here's a basic example of how to implement this:
Copy code
python
# Lambda function
import boto3
from prefect.client import get_client

async def lambda_handler(event, context):
    # Get S3 event details
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = event['Records'][0]['s3']['object']['key']
    
    async with get_client() as client:
        # Replace with your deployment name
        flow_run = await client.create_flow_run_from_deployment(
            deployment_id="deployment-name",
            parameters={
                "bucket": bucket,
                "key": key
            }
        )
2. Using 
prefect-aws
Integration (Recommended): - Install the 
prefect-aws
collection: 
pip install prefect-aws
- Use the S3 event trigger functionality Here's how to set it up using `prefect-aws`:
Copy code
python
from prefect import flow
from prefect_aws.s3 import S3Bucket
from prefect_aws.events import S3Event, run_on_s3_event

@flow
def process_s3_file(bucket: str, key: str):
    print(f"Processing file {key} from bucket {bucket}")
    # Your processing logic here

# Configure the trigger
s3_trigger = S3Event(
    bucket_name="your-bucket-name",
    event_names=["ObjectCreated:Put"],  # Triggers on file uploads
    prefix="optional/path/prefix/"  # Optional: only trigger for files in this prefix
)

# Decorate your flow with the trigger
@run_on_s3_event(s3_trigger)
def triggered_flow(event):
    bucket = event.bucket_name
    key = event.object_key
    process_s3_file(bucket=bucket, key=key)
Important Notes: 1. Make sure you have the necessary AWS permissions configured 2. For the Lambda approach, you'll need to: - Configure AWS credentials properly - Set up the appropriate IAM roles - Configure the S3 bucket to send events to Lambda 3. For the 
prefect-aws
approach: - Install the collection: 
pip install prefect-aws
- Configure AWS credentials using Prefect blocks or environment variables - Ensure your worker has access to AWS Best Practices: - Always include error handling in your flows - Consider using AWS credentials blocks in Prefect for secure credential management - Monitor your flow runs to ensure triggers are working as expected - Consider implementing dead letter queues or retry policies for robustness Would you like me to provide more specific details about either approach or help with setting up the AWS credentials and permissions?
b
Is it possible to configure the trigger in the 
prefect.yaml
config file?
@Marvin Is it possible to configure the trigger in the 
prefect.yaml
config file?
m
✅ thought for 59.5 seconds
Yes, it is possible to configure triggers in your project's configuration! For S3 triggers, you can define them in a separate YAML file (e.g., 
triggers.yaml
) and reference it during deployment. Here's how to do it: 1. First, create a trigger configuration file (e.g., 
triggers.yaml
):
Copy code
yaml
enabled: true
match:
  prefect.resource.id: "aws.s3"
  bucket: "your-bucket-name"
expect:
  - "s3:ObjectCreated:*"
parameters:
  bucket: "${match.bucket}"
  key: "${event.key}"
2. When deploying your flow, you can reference this trigger configuration:
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bash
prefect deploy ./path/to/flow.py:flow_name --trigger triggers.yaml
Or you can include the trigger configuration directly in your 
prefect.yaml
project file:
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yaml
deployments:
  - name: s3-triggered-flow
    entrypoint: flows/process_s3.py:process_s3_file
    triggers:
      - enabled: true
        match:
          prefect.resource.id: "aws.s3"
          bucket: "your-bucket-name"
        expect:
          - "s3:ObjectCreated:*"
        parameters:
          bucket: "${match.bucket}"
          key: "${event.key}"
Important Notes: 1. Make sure you have the 
prefect-aws
collection installed: 
pip install prefect-aws
2. The trigger configuration needs to match the AWS S3 event pattern you want to respond to 3. You can use template variables like 
${match.bucket}
and 
${event.key}
to access event data 4. The 
prefect.resource.id
should match the AWS S3 resource identifier Best Practices: - Keep trigger configurations in separate files for better organization when you have multiple triggers - Use version control for your trigger configurations - Test your trigger configurations with small test files before deploying to production - Monitor your triggered flows to ensure they're responding as expected Would you like me to provide more details about specific trigger configuration options or help with testing the trigger setup?
b
@Marvin I just want to confirm that these types of triggers are compatible in the open-source self-hosted version of Prefect?
m
✅ thought for 49.2 seconds
I need to correct my previous response. After researching this specifically, I need to be more precise about triggers in self-hosted Prefect: Important Clarification: The event-based triggers as described in my previous response (using 
prefect.yaml
and trigger configurations) are actually a Prefect Cloud feature and are not available in the open-source self-hosted version of Prefect. For self-hosted Prefect, you would need to implement one of these alternative approaches: 1. Recommended Approach: Custom Event-Driven Architecture
Copy code
python
   from prefect import flow
   from prefect.client import get_client

   # Your Lambda function or event handler
   async def handle_s3_event(bucket, key):
       async with get_client() as client:
           # Create a flow run from your deployment
           flow_run = await client.create_flow_run_from_deployment(
               deployment_id="your-deployment-id",
               parameters={
                   "bucket": bucket,
                   "key": key
               }
           )
2. Using AWS Lambda with API Calls - Set up an AWS Lambda function that watches your S3 bucket - Have the Lambda function call your self-hosted Prefect API to trigger flows - Use the Prefect REST API or Python client to create flow runs 3. Using the 
prefect-aws
Collection with Custom Scheduling - While the event triggers aren't available, you can still use the AWS integration - Implement your own event detection logic within scheduled flows Key Points: - Event-based triggers through the 
prefect.yaml
configuration are a Prefect Cloud feature - Self-hosted Prefect still supports programmatic flow run creation through its API - You can implement similar functionality using custom code and AWS services - The 
prefect-aws
collection is still useful for AWS interactions, even without native event triggers Would you like me to provide more detailed implementation examples for any of these alternative approaches?
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