Slack Notification failing for Alerts with large number of affected sources (Host-Label pairs)

Products

• Insights

Issue/Introduction

This article applies to:

• Alerting

•Product edition: Current

•Feature Category: Alerting

 

Problem description:

In VMware Aria Operations for Application(AoA), for the alerts which are using slack target are unable to receive notifications over slack when the number of affected sources is high. However, there is no issue with e-mail notifications.

 

Cause:
This is mainly happening because the text field of the slack template has a limit of 3000 characters as per the slack documentation - https://api.slack.com/reference/block-kit/composition-objects#text 
For my case, I checked the word count using - https://easywordcount.com/ and it was showig characters count as 3728.

We checked from the error logs that this has been failing due to the "invalid_blocks" error. 

 

Workaround:
Reducing the limit will help in this case. We tried with 25 (setFailingLimit) and the webhook notification is coming through.