AWS SNS Notification Message Limit

Dylan,

This is a limit imposed by Amazon.

Amazon SNS FAQs

Q: What is the format of an Amazon SNS topic?

Topic names are limited to 256 characters. Alphanumeric characters plus hyphens (-) and underscores (_) are allowed. Topic names must be unique within an AWS account. After you delete a topic, you can reuse the topic name. When a topic is created, Amazon SNS will assign a unique ARN (Amazon Resource Name) to the topic, which will include the service name (SNS), region, AWS ID of the user and the topic name. The ARN will be returned as part of the API call to create the topic. Whenever a publisher or subscriber needs to perform any action on the topic, they should reference the unique topic ARN.

The following is the ARN for a topic named “mytopic” created by a user with the AWS account ID “123456789012” and hosted in the US East region:

arn:aws:sns:us-east-1:1234567890123456:mytopic Note: Users should NOT attempt to build the topic ARN from its separate components – they should always use the name returned from the API call to create the topic.

Let me know if I can answer any other questions.

Benjamin Day
Paessler Support

Hi Benjamin,

The AWS SNS topic names are limited to 255 characters however the SNS body message/payload can be up to 256KB - https://aws.amazon.com/about-aws/whats-new/2013/06/18/amazon-sqs-announces-256KB-large-payloads/ The PRTG SNS notification 'message' isn't the AWS SNS 'Topic' but the publised payload by the Topic created already in the AWS dashboard.

Not sure if my last reply went through. Yes this is true that SNS topics are limited to 255 characters, but the topic is created in the AWS console and the ARN that the PRTG notification publishes to is linked to this topic. PRTG is publishing a message/payload to that topic therefore has a limit of up to 265 KB if using the 'Large Payloads'

Dylan,

Are you sending these out via email or SMS? I apologize for my lack of knowledge regarding SNS. From what I've gathered, a message is sent to Amazon, and you can then either have it email or send you an SMS message based on that. Is that correct, or am I way off?

Benjamin Day
Paessler Support

That is correct. I am using the Amazon SNS service to trigger internal Amazon Lambda functions within my stack. The alerts never get posted to email, SMS or anywhere else by the SNS service. This message character limit appears to be imposed by the PRTG notification service rather than Amazon SNS. See the link in my first reply as SNS can do up to 256KB payloads. Thanks for your response.

Dylan,

One of my colleagues helped out here to clear this up.

"The message part is only sent if you use email based notifications delivered by Amazon SNS." --> I think that would be the "body" he refers to, which can be indeed be quite huge, up to 256kB payload.

However, since he does not trigger an email through this SNS voodoo, the whole message block is disregarded, only the subject will be used and "The maximum length for the subject is 202 characters. Characters that exceed this number will be cut off."

I think this is why you're getting cut off. Thoughts?

Benjamin Day
Paessler Support

It is definitely coming through on the 'message' part of the SNS rather than the 'subject'. I can send you the JSON of the incoming SNS message if you would like to take a look.

Dyaln,

Sure, please do.

Benjamin Day
Paessler Support

Hi Benjamin,

Has there been any further progress on this issue? It still appears that there is a 256 character limit for SNS messages published by PRTG alerts. This limit does not exist on the AWS side as I have just tested this manually. I am triggering an email with the SNS.

Regards Dylan

Dylan,

Did you send a support ticket in with the JSON? I would have opened a ticket with my devs, but I don't have any tickets opened from your email on file, [email protected].

Can you look back through, and see if you have a ticket number for the case in a different inbox?

Benjamin Day
Paessler Support