Welcome! Today, I am going to show you how to write an AWS Lambda Function that sends an SNS notification.
๐ฆ Follow me on Twitter if you would like to see more content like this! ๐ฆ
TLDR - Here is a link to my Github with the given code.
1. Initialize the Project
You can follow my previous post on how to use AWS SAM to spin up a boilerplate Lambda function.
2. Email
First, let's write a function to send an email and return a promise.
function sendEmail(message){ const awsRegion = "us-east-1"; // FIXME - update this ARN const snsTopic = 'arn:aws:sns:us-east-1:12341234-ABCDABCD'; const snsSubject = 'SNS Subject'; // Create publish parameters var params = { Message: message, Subject: snsSubject, TopicArn: snsTopic }; var sns = new AWS.SNS({ region: awsRegion }); return sns.publish(params).promise(); }
3. Next, we bring it all together in the handler.
const AWS = require("aws-sdk");
/**
* A Lambda function that sends an SNS message
*/
exports.handler = (event, context) => {
let message = "Hello from Lambda!";
return sendEmail(msg).then((err,data)=>{
console.log ("We are in the callback!");
if (err) {
console.log('Error sending a message', err);
context.fail(err);
} else {
console.log('Sent message:', data.MessageId);
context.succeed("Done!");
}
});
};
...
...
4. Add an SNS Role
You will need to add a policy for this Lambda to be able to properly send SNS messages. We need to make a small update to the CloudFormation template to make use of this. If you did not use AWS SAM to generate the project, you can simply update the assigned role using the AWS Console.
snsLambdaFunction: Type: AWS::Serverless::Function Properties: Handler: src/handlers/index.handler Runtime: nodejs12.x MemorySize: 128 Timeout: 100 Description: A Lambda function sends an SNS notification. Policies: # Give Lambda basic execution Permission to the helloFromLambda - AWSLambdaBasicExecutionRole # This is the new policy - AmazonSNSFullAccess
TLDR - Here is a link to my Github with the given code.
๐ฆ Follow me on Twitter if you would like to see more content like this! ๐ฆ
Conclusion
That's it! In a couple of dozen lines of code, you can easily utilize SNS subscriptions to send notifications.