Publish Event SNS

Warnings

• gotcha The `publish-event-sns` library (v0.0.3) has minimal public documentation. The provided import paths and quickstart are based on assumptions of a thin wrapper around `boto3`. If the library's internal API differs, direct `boto3` usage for `sns.publish` will be necessary.
  Fix: Consult the library's source code on GitHub (if available and maintained) for its exact API, or default to using `boto3` directly for SNS publishing.
• breaking AWS IAM permissions are crucial. The AWS user or role publishing messages must have `sns:Publish` permission for the target SNS topic. Without it, `boto3.client('sns').publish` (and by extension, likely `publish-event-sns`) calls will result in an `AuthorizationError` or similar access denied exceptions.
  Fix: Ensure your AWS IAM policy grants `sns:Publish` to the SNS topic's ARN. Example: `{"Action": ["sns:Publish"], "Effect": "Allow", "Resource": "arn:aws:sns:REGION:ACCOUNT_ID:YOUR_TOPIC_NAME"}`.
• gotcha Messages published to SNS have a size limit of 256 KB (262,144 bytes). For SMS, the limit is 140-160 characters depending on encoding. Attempting to publish larger messages will result in an error.
  Fix: For messages exceeding 256KB, consider using the `amazon-sns-extended-client` library which leverages S3 to store large payloads and publishes an S3 object reference to SNS.
• gotcha SNS FIFO topics require `MessageGroupId` and optionally `MessageDeduplicationId` parameters. Publishing to a FIFO topic without these will result in an error. Standard topics do not require these.
  Fix: When publishing to an SNS FIFO topic, include `MessageGroupId` and `MessageDeduplicationId` in your `publish` call parameters. For example: `sns_client.publish(TopicArn=topic_arn, Message=json.dumps(message), MessageGroupId='your_group_id')`.
• gotcha If the publishing environment (e.g., AWS Lambda, EC2 instance) is within a private VPC, ensure it has outbound internet access via a NAT Gateway or a VPC endpoint for SNS to reach the SNS service. Otherwise, publish calls may time out.
  Fix: Configure a NAT Gateway in a public subnet for your private VPC subnets, or create a VPC endpoint for SNS in your account.

Install

• pip install publish-event-sns Install latest version

Imports

• publish_event

  from publish_event_sns import publish_event

  Assumed main function/class based on library name and common Python packaging patterns; specific API is not documented. If this import fails, direct boto3 usage (import boto3) is the alternative.

Quickstart

This quickstart demonstrates how to publish a structured message with attributes to an AWS SNS topic. It assumes the `publish-event-sns` library wraps `boto3`'s SNS client. It includes a fallback to direct `boto3` usage if the specific `publish_event_sns` module cannot be imported or its API differs, ensuring the example remains functional for general SNS publishing. AWS credentials (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY) and the AWS_REGION should be configured via environment variables or other boto3-supported methods. The SNS_TOPIC_ARN must be replaced with your actual topic ARN.

import os
import json
from publish_event_sns import publish_event # Assumed import based on library name

# Fallback to boto3 if 'publish_event_sns' module is not found or has a different API
try:
    from publish_event_sns import publish_event
except ImportError:
    import boto3
    print("Using boto3 directly as 'publish_event_sns' module not found or API differs.")
    def publish_event(topic_arn, message, message_attributes=None, region_name=None):
        sns_client = boto3.client(
            'sns',
            region_name=region_name or os.environ.get('AWS_REGION', 'us-east-1'),
            aws_access_key_id=os.environ.get('AWS_ACCESS_KEY_ID', ''),
            aws_secret_access_key=os.environ.get('AWS_SECRET_ACCESS_KEY', '')
        )
        response = sns_client.publish(
            TopicArn=topic_arn,
            Message=json.dumps(message),
            MessageAttributes=message_attributes or {}
        )
        return response

# Replace with your actual SNS Topic ARN
SNS_TOPIC_ARN = os.environ.get('SNS_TOPIC_ARN', 'arn:aws:sns:REGION:ACCOUNT_ID:YOUR_TOPIC_NAME')

# Example message and attributes
event_message = {
    'detail-type': 'OrderCreated',
    'source': 'my.application',
    'detail': {
        'orderId': '12345',
        'customerEmail': 'test@example.com'
    }
}

message_attrs = {
    'eventType': {
        'DataType': 'String',
        'StringValue': 'OrderCreated'
    },
    'priority': {
        'DataType': 'Number',
        'StringValue': '1'
    }
}

try:
    response = publish_event(SNS_TOPIC_ARN, event_message, message_attrs, region_name='us-east-1')
    print(f"Message published: {response.get('MessageId')}")
except Exception as e:
    print(f"Error publishing message: {e}")
    print("Ensure AWS credentials and SNS_TOPIC_ARN are correctly configured.")