Unable to send data to SNS from lambda using designer vew - amazon-web-services

Question

When following Introducing AWS Lambda Destinations I'm told to create an SNS as destination, I do that:
But it doesn't send anything. I had already an SNS able to send mail to my account, and I have adapted the policy to accept everything from everyone (it works with the 'Publish another message' button)
If I call the sns from code it works:
if (event.Success) {
console.log("Success");
context.callbackWaitsForEmptyEventLoop = false;
var sns = new AWS.SNS();
sns.publish({
Message: 'File(s) uploaded successfully',
TopicArn: 'arn:aws:sns:XXX:YYY:ZZZ'
}, (err,data) => {
if (err) {
console.log(err.stack);
return;
}
callback(null);
});
}
But I was hoping not having to write code for that (that what's suggested from the blog entry) so for example if I change the SNS topic I don't have to change the code.
Have any of you succeeded in doing this?
Thanks,

Answer 1

I have reviewed and replicated the AWS Lambda Destinations blog successfully without modifying the sample code snippet from the blog.
I would suggest, you review your SNS configuration (and change us-west-2 region to your AWS region of use as need be) and check if it matches the following:
1. On your SNS topic ('arn:aws:sns:us-west-2:1234567890:YourSNSTopicOnSuccess'), navigate to the access policy and check if you have a policy similar to the following :
{
"Version": "2008-10-17",
"Id": "__default_policy_ID",
"Statement": [
{
"Sid": "__default_statement_ID",
"Effect": "Allow",
"Principal": {
"Service": "lambda.amazonaws.com"
},
"Action": [
"SNS:GetTopicAttributes",
"SNS:SetTopicAttributes",
"SNS:AddPermission",
"SNS:RemovePermission",
"SNS:DeleteTopic",
"SNS:Subscribe",
"SNS:ListSubscriptionsByTopic",
"SNS:Publish",
"SNS:Receive"
],
"Resource": "arn:aws:sns:us-west-2:1234567890:YourSNSTopicOnSuccess"
}
]
}
2. On your Lambda role ('arn:aws:iam::1234567890:role/YourLambdaDestinationRole'), make sure of the following:
(i) The "Trust relationship" of your role has the following statement :
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service":"lambda.amazonaws.com"
},
"Action": "sts:AssumeRole"
}
]
}
(ii) The Lambda role has an attached policy document similar to one given below:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"sns:publish"
],
"Resource": "*"
}
]
}
The successful published message from Amazon Lambda to SNS topic should output something similar to:
{"version":"1.0","timestamp":"2020-03-22T16:29:50.528Z","requestContext":{"requestId":"43d109d2-54be-4e2e-b8d8-2757e3f06f76","functionArn":"arn:aws:lambda:eu-west-1:1234567890:function:event-destinations:$LATEST","condition":"Success","approximateInvokeCount":1},"requestPayload":{ "Success": true },"responseContext":{"statusCode":200,"executedVersion":"$LATEST"},"responsePayload":null}
Hope this helps.