notification-sender

A Java based AWS Lambda to send notifications via Amazon SNS (Amazon Simple Notification Service).

Setup

AWS Lambda

Choose the latest version of the Java runtime
The handler is eu.ortlepp.notificationsender.NotificationHandler::handleRequest
The recommended timeout is 30 seconds
The recommended RAM is 512 MB
Two environment variables are required to run the Lambda:
REGION - the region of your SNS topic, e.g. eu-central-1
ARN - the ARN of your SNS topic, something like arn:aws:sns:eu-central-1:123456789:Topic-Name
Create a function URL to trigger the Lambda
It is recommended to secure the function URL with IAM

Amazon SNS

Create a new topic; in the topic, create a subscription
Only e-mail subscriptions have been tested so far; other subscription types are untested

Data

Input (request)

HTTP POST to the function URL with JSON body:

{
  "messages" : ["first notification", "second notification"]
}

Output (response)

The response is HTTP 200 with either

{
  "status" : "SUCCESS"
}

or

{
  "status" : "FAILED"
}

If the Lambda setup is improper, a timeout occurred, etc., the response is HTTP 500 from the AWS environment (not the Lambda itself).

If the messages array contains multiple messages, all elements of the messages array are combined into one SNS message. Empty messages (empty / whitespace-only string) are omitted.

Only one message:

my notification

Multiple messages:

1. Notification:
first notification

2. Notification:
second notification

SNS will automatically append an unsubscribe footer to each e-mail.

Testing

You can use curl to trigger your Lambda:

curl -X POST -H "Content-Type: application/json" -d "{\"messages\":[\"my notification\"]}" --aws-sigv4 "aws:amz:eu-central-1:lambda" --user "ACCESS_KEY:SECRET_KEY" https://MY_FUNCTION_URL.lambda-url.eu-central-1.on.aws/