This assumes you have already configured the aws command line tool. If not, check out my article on Getting Started with the AWS CLI.

A Simple Notification Service (SNS) Topic can be used to create notification alerts, such as an email notification. This uses the messaging services pub sub model.

• pub (publish) - create a new alert in a Topic
• sub (subscribe) - get alerts in a Topic

The aws sns list-topics command can be used to list your Simple Notification Service (SNS) Topics.

aws sns list-topics

Something like this should be returned.

{
    "Topics": [
        {
            "TopicArn": "arn:aws:sns:us-east-1:123456789012:myTopic.fifo"
        }
    ]
}

And the aws sns list-subscriptions command can be used to list the subscriptions to the topic. In this example, John Doe is subscribed to the topic, so John Doe should get an email when a message is put on the topic.

~]$ aws sns list-subscriptions
{
    "Subscriptions": [
        {
            "SubscriptionArn": "arn:aws:sns:us-east-1:123456789012:mytopic:0f8966a4-1bf9-48fa-8564-5b4ecab489c2",
            "Owner": "123456789012",
            "Protocol": "email",
            "Endpoint": "john.doe@example.com",
            "TopicArn": "arn:aws:sns:us-east-1:123456789012:mytopic"
        }
    ]
}

The aws sns publish command can be used to publish a message to the topic, which in this example should send an email to john.doe@example.com.

~]$ aws sns publish --subject Hello --message World --topic-arn arn:aws:sns:us-east-1:123456789012:mytopic
{
    "MessageId": "3756dea6-80cd-5e4a-ba9a-80a33a856481"
}

The IAM role associated with the user attempting to publish the message will need to allow sns:Publish.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "sns:Publish"
            ],
            "Resource": "*"
        }
    ]
}

Or, if you are subscribing a Lambda Function to one of your SNS Topics, the aws lambda add-permission command can be used to allow the SNS Topic to invoke the Lambda Function.

aws lambda add-permission \
--function-name sendgrid \
--source-arn arn:aws:sns:us-east-1:12346789012:my-topic \
--statement-id allow-sns-to-invoke-lambda \
--action "lambda:InvokeFunction" \
--principal sns.amazonaws.com

This command attaches the following IAM Policy to the Lambda Function, allowing the SNS Topic to invoke the Lambda Function.

{
  "Version": "2012-10-17",
  "Id": "default",
  "Statement": [
    {
      "Sid": "allow-sns-to-invoke-lambda",
      "Effect": "Allow",
      "Principal": {
        "Service": "sns.amazonaws.com"
      },
      "Action": "lambda:InvokeFunction",
      "Resource": "arn:aws:lambda:us-east-1:123456789012:function:my-lambda-function",
      "Condition": {
        "ArnLike": {
          "AWS:SourceArn": "arn:aws:sns:us-east-1:123456789012:my-sns-topic"
        }
      }
    }
  ]
}