Amazon SNS

Events can be sent to an Amazon SNS topic using the sns sink type.

Like all Sinks, SNS sinks can be created in the Stream Portal…

sns-create


curl -X 'POST' 'https://api.svix.com/api/v1/stream/strm_30XKA2tCdjHue2qLkTgc0/sink' \
  -H 'Authorization: Bearer AUTH_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{
  "type": "sns",
  "config": {
    "topicArn": "arn:aws:sns:us-east-1:000000000000:my-topic",
    "region": "us-east-1",
    "accessKeyId": "AKIA3LIKMTLDNWBX2PPD",
    "secretAccessKey": "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"
  },
  "uid": "unique-identifier",
  "status": "enabled",
  "batchSize": 1000,
  "maxWaitSecs": 300,
  "eventTypes": [],
  "metadata": {}
}'

Every event in the batch is published to the topic as a separate message.

topicArn — the ARN of the SNS topic to publish to.
region, accessKeyId, secretAccessKey — the AWS region and credentials used to authenticate.

Transformations

By default, all sns Sinks come bundled with the following transformation code.


/**
 * @param input - The input object
 * @param input.events - The array of events in the batch. The number of events in the batch is capped by the Sink's batch size.
 * @param input.events[].payload - The message payload (string or JSON).
 * @param input.events[].eventType - The message event type (string).
 *
 * @returns Object containing the response.
 * @returns returns.messages - The array of SNS messages to send to the SNS topic.
 * @returns returns.messages[].payload - The content of the message (string).
 * @returns returns.messages[].subject - An optional subject of the message (string).
 */
function handler(input) {
  const messages = input.events.map((event) => ({
    payload: event,
  }));

  return {
    messages,
  };
}

input.events matches the events sent in create_events.

Each entry in the returned messages array is published as a separate SNS message. The payload becomes the message body, and the optional subject becomes the SNS subject. By default, each event is published as its serialized JSON, with no subject.

For example, if the following events are written to the stream:


curl -X 'POST' \
  'https://api.svix.com/api/v1/stream/{stream_id}/events' \
  -H 'Authorization: Bearer AUTH_TOKEN' \
  -H 'Accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
        "events": [
            {
                "eventType": "user.created",
                "payload": "{\"email\": \"joe@enterprise.io\"}"
            },
            {
                "eventType": "user.login",
                "payload": "{\"id\": 12, \"timestamp\": \"2025-07-21T14:23:17.861Z\"}"
            }
        ]
    }'

The default transformation code would publish two messages to your topic, with the following bodies.


{"payload":{"email":"joe@enterprise.io"},"eventType":"user.created"}


{"payload":{"id":12,"timestamp":"2025-07-21T14:23:17.861Z"},"eventType":"user.login"}

To control the message bodies, or to set a subject, return your own array of messages. Each message’s payload becomes the body of one SNS message, and subject is published as that message’s SNS subject.


function handler(input) {
  const messages = input.events.map((event) => ({
    payload: JSON.stringify(event.payload),
    subject: event.eventType
  }));

  return {
    messages,
  };
}

SNS accepts at most 10 messages per batch request, so larger batches are automatically split across multiple PublishBatch calls.