AWS SNS can't confirm the subscription

Describe the problem/error/question

Hello. I’ve created two workflows. One to send messages into SNS queue and another one with SNS trigger to receive them.

Everything is ok with sending to the queue, however I’m experiencing problems with trigger flow. I see that it exists in the SNS subscriptions in the pending state, but when I send a “Request confirmation” command from the AWS side, nothing happened (the flow didn’t display anything).

So I have no idea how to get the confirmation in order to use the subscription. And I don’t know how to check if the workflow receives something.

Is anyone got it working?

Information on your n8n setup

  • n8n version: 1.4.0
  • Running n8n via (Docker, npm, n8n cloud, desktop app): docker

Hi @barn4k, I am sorry you’re having trouble. I created multiple subscriptions but didn’t run into any trouble here:

Is there a chance your webhook URLs aren’t publicly accessible for AWS SNS (for example because they are being blocked by your reverse proxy, a service such as Cloudflare, or because you’re using an internal hostname or localhost as your instance URL)?

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Wel… I’m using AWS ALB for n8n which has an IP whitelist and some path rules, so maybe that is the problem. But the path seems working fine (tested with curl). I have excluded /webhook/* and /webhook-test/* from our internal authentication provider.

But how the confirmation process should work in the normal way?

  1. You are creating an SNS trigger node (webhook)
  2. Activating it
  3. in the AWS console pressing the ‘Confirm’ button
  4. And all is working?

Hi @barn4k, I do not have to press the “Confirm” button. Activating your workflow (or manually executing it) should register the URL with AWS SNS and also handle the confirmation defined on Step 3: Confirm the subscription - Amazon Simple Notification Service.

So this is why I suspect SNS might not reach the webhook URL n8n is sending here. Does your load balancer have HTTP access logs and do you see the requests coming in from AWS SNS (and ideally also the response status code)?

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