Sns Agent Skill
AWS SNS notification service for pub/sub messaging. Use when creating topics, managing subscriptions, configuring message filtering, sending notifications, or setting up mobile push.
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/itsmostafa/aws-agent-skills --skill snsThe instruction itself
28 sections, as written by the authorAWS SNS
Amazon Simple Notification Service (SNS) is a fully managed pub/sub messaging service for application-to-application (A2A) and application-to-person (A2P) communication.
Table of Contents
- Core Concepts
- Common Patterns
- CLI Reference
- Best Practices
- Troubleshooting
- References
Core Concepts
Topics
Named channels for publishing messages. Publishers send to topics, subscribers receive from topics.
Topic Types
| Type | Description | Use Case |
|------|-------------|----------|
| Standard | Best-effort ordering, at-least-once | Most use cases |
| FIFO | Strict ordering, exactly-once | Order-sensitive |
Subscription Protocols
| Protocol | Description |
|----------|-------------|
| Lambda | Invoke Lambda function |
| SQS | Send to SQS queue |
| HTTP/HTTPS | POST to endpoint |
| Email | Send email |
| SMS | Send text message |
| Application | Mobile push notification |
Message Filtering
Route messages to specific subscribers based on message attributes.
Common Patterns
Create Topic and Subscribe
AWS CLI:
# Create standard topic
aws sns create-topic --name my-topic
# Create FIFO topic
aws sns create-topic \
--name my-topic.fifo \
--attributes FifoTopic=true
# Subscribe Lambda
aws sns subscribe \
--topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
--protocol lambda \
--notification-endpoint arn:aws:lambda:us-east-1:123456789012:function:my-function
# Subscribe SQS
aws sns subscribe \
--topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
--protocol sqs \
--notification-endpoint arn:aws:sqs:us-east-1:123456789012:my-queue
# Subscribe email
aws sns subscribe \
--topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
--protocol email \
--notification-endpoint [email protected]
boto3:
import boto3
sns = boto3.client('sns')
# Create topic
response = sns.create_topic(Name='my-topic')
topic_arn = response['TopicArn']
# Subscribe Lambda
sns.subscribe(
TopicArn=topic_arn,
Protocol='lambda',
Endpoint='arn:aws:lambda:us-east-1:123456789012:function:my-function'
)
# Subscribe SQS with filter
sns.subscribe(
TopicArn=topic_arn,
Protocol='sqs',
Endpoint='arn:aws:sqs:us-east-1:123456789012:order-queue',
Attributes={
'FilterPolicy': '{"event_type": ["order_created", "order_updated"]}'
}
)
Publish Messages
import boto3
import json
sns = boto3.client('sns')
topic_arn = 'arn:aws:sns:us-east-1:123456789012:my-topic'
# Simple publish
sns.publish(
TopicArn=topic_arn,
Message='Hello, World!',
Subject='Notification'
)
# Publish with attributes (for filtering)
sns.publish(
TopicArn=topic_arn,
Message=json.dumps({'order_id': '12345', 'status': 'created'}),
MessageAttributes={
'event_type': {
'DataType': 'String',
'StringValue': 'order_created'
},
'priority': {
'DataType': 'Number',
'StringValue': '1'
}
}
)
# Publish to FIFO topic
sns.publish(
TopicArn='arn:aws:sns:us-east-1:123456789012:my-topic.fifo',
Message=json.dumps({'order_id': '12345'}),
MessageGroupId='order-12345',
MessageDeduplicationId='unique-id'
)
Message Filtering
# Add filter policy to subscription
aws sns set-subscription-attributes \
--subscription-arn arn:aws:sns:us-east-1:123456789012:my-topic:abc123 \
--attribute-name FilterPolicy \
--attribute-value '{
"event_type": ["order_created"],
"priority": [{"numeric": [">=", 1]}]
}'
Filter policy examples:
// Exact match
{"event_type": ["order_created", "order_updated"]}
// Prefix match
{"customer_id": [{"prefix": "PREMIUM-"}]}
// Numeric comparison
{"price": [{"numeric": [">=", 100, "<=", 500]}]}
// Exists check
{"customer_id": [{"exists": true}]}
// Anything but
{"event_type": [{"anything-but": ["deleted"]}]}
// Combined
{
"event_type": ["order_created"],
"region": ["us-east", "us-west"],
"priority": [{"numeric": [">=", 1]}]
}
Fan-Out Pattern (SNS to Multiple SQS)
import boto3
import json
sns = boto3.client('sns')
sqs = boto3.client('sqs')
# Create topic
topic = sns.create_topic(Name='orders-topic')
topic_arn = topic['TopicArn']
# Create queues for different processors
queues = {
'analytics': sqs.create_queue(QueueName='order-analytics')['QueueUrl'],
'fulfillment': sqs.create_queue(QueueName='order-fulfillment')['QueueUrl'],
'notification': sqs.create_queue(QueueName='order-notification')['QueueUrl']
}
# Subscribe each queue
for name, queue_url in queues.items():
queue_arn = sqs.get_queue_attributes(
QueueUrl=queue_url,
AttributeNames=['QueueArn']
)['Attributes']['QueueArn']
sns.subscribe(
TopicArn=topic_arn,
Protocol='sqs',
Endpoint=queue_arn
)
# One publish reaches all queues
sns.publish(
TopicArn=topic_arn,
Message=json.dumps({'order_id': '12345', 'total': 99.99})
)
Lambda Permission for SNS
aws lambda add-permission \
--function-name my-function \
--statement-id sns-trigger \
--action lambda:InvokeFunction \
--principal sns.amazonaws.com \
--source-arn arn:aws:sns:us-east-1:123456789012:my-topic
CLI Reference
Topic Management
| Command | Description |
|---------|-------------|
| aws sns create-topic | Create topic |
| aws sns delete-topic | Delete topic |
| aws sns list-topics | List topics |
| aws sns get-topic-attributes | Get topic settings |
| aws sns set-topic-attributes | Update topic settings |
Subscriptions
| Command | Description |
|---------|-------------|
| aws sns subscribe | Create subscription |
| aws sns unsubscribe | Remove subscription |
| aws sns list-subscriptions | List all subscriptions |
| aws sns list-subscriptions-by-topic | List topic subscriptions |
| aws sns confirm-subscription | Confirm pending subscription |
Publishing
| Command | Description |
|---------|-------------|
| aws sns publish | Publish message |
Best Practices
Reliability
- Use SQS for durability — SNS is push-based, SQS queues messages
- Implement retries for HTTP/HTTPS endpoints
- Configure DLQ for failed deliveries
- Use FIFO topics for ordering requirements
Security
- Use topic policies to control access
- Enable encryption with SSE
- Use VPC endpoints for private access
# Enable SSE
aws sns set-topic-attributes \
--topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
--attribute-name KmsMasterKeyId \
--attribute-value alias/my-key
Cost Optimization
- Use message filtering to reduce unnecessary deliveries
- Batch operations where possible
- Monitor and clean up unused topics/subscriptions
Message Design
- Keep messages small (256 KB limit)
- Use message attributes for routing
- Include correlation IDs for tracing
Troubleshooting
Subscription Not Receiving Messages
Check:
- Subscription is confirmed (not pending)
- Filter policy matches message attributes
- Target permissions (Lambda, SQS)
# Check subscription status
aws sns list-subscriptions-by-topic \
--topic-arn arn:aws:sns:us-east-1:123456789012:my-topic
# Check subscription attributes
aws sns get-subscription-attributes \
--subscription-arn arn:aws:sns:us-east-1:123456789012:my-topic:abc123
HTTP Endpoint Not Working
Debug:
# Check delivery status logging
aws sns set-topic-attributes \
--topic-arn arn:aws:sns:us-east-1:123456789012:my-topic \
--attribute-name DeliveryPolicy \
--attribute-value '{
"http": {
"defaultHealthyRetryPolicy": {
"minDelayTarget": 20,
"maxDelayTarget": 20,
"numRetries": 3,
"numMaxDelayRetries": 0,
"numNoDelayRetries": 0,
"numMinDelayRetries": 0,
"backoffFunction": "linear"
}
}
}'
Messages Not Matching Filter
Verify:
- Message attributes are set (not in body)
- Attribute types match (String vs Number)
- Filter policy syntax is correct
# Correct: attributes must be message attributes
sns.publish(
TopicArn=topic_arn,
Message='body content',
MessageAttributes={
'event_type': {
'DataType': 'String',
'StringValue': 'order_created' # This is filtered
}
}
)
# Wrong: this won't be filtered
sns.publish(
TopicArn=topic_arn,
Message=json.dumps({'event_type': 'order_created'}) # Not filtered
)
SQS Not Receiving from SNS
Check SQS queue policy:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {"Service": "sns.amazonaws.com"},
"Action": "sqs:SendMessage",
"Resource": "arn:aws:sqs:us-east-1:123456789012:my-queue",
"Condition": {
"ArnEquals": {
"aws:SourceArn": "arn:aws:sns:us-east-1:123456789012:my-topic"
}
}
}
]
}
References
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How to use it
Take itsmostafa/sns from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.