Sending AWS SNS message subscription into Slack workflow

A no-code solution to push messages sent to an AWS SNS topic into Slack via a workflow webhook.

Create a new Slack Workflow, using From a webhook as the triggering event.
Include the following Data variables:
```
Message
Token
```
Next, add a Slack Workflow step to Send a message to... a nominated channel with Message and Token values included.
Publish the Slack Workflow and obtain the Web request URL from the opening event trigger step.
Create an SNS topic subscription where:
- Protocol is HTTP.
- Endpoint is Web request URL from previous step.
SNS will now call Web request URL, and you will receive a Slack message from the Workflow containing Message and Token values.

Using the Token, confirm the SNS topic subscription via the AWS CLI:

$ aws sns confirm-subscription --topic-arn SNS_TOPIC_ARN --token LONG_TOKEN_STRING
{
  "SubscriptionArn": "SUBSCRIPTION_ARN"
}

Finally, go back to your Slack Workflow and update the message body/add additional triggering actions/etc. You can remove Token from the From a webhook initial step, as no longer required.
Done!

magnetikonline/README.md