Introduction

This action temporarily changes the visibility timeout of an SQS queue using the SetQueueAttributes API. The pre-attack value is captured during Prepare and restored on Stop.

Set the target value very low (0-5s) to force premature message redelivery, or very high (e.g. 12 hours) to stall in-flight messages.

Use Cases

• Stress consumer idempotency by forcing the same message to be redelivered while still being processed.
• Validate consumer behaviour when in-flight messages stay invisible for extended periods.
• Test the dead-letter queue / maxReceiveCount path by inflating redelivery rates.

Rollback

The queue's original visibility timeout is captured during Prepare and restored on Stop.

New messages enqueued during the experiment inherit the modified timeout; messages already in flight keep their assigned visibility window until their next visibility change.

Observed AWS-side behaviour for the visibility-timeout parameter

• In-flight messages are not affected — SetQueueAttributes only updates the queue's default visibility timeout, which is applied to messages at the moment they are received. Messages already in flight when the attack starts keep the visibility window they were assigned at their original ReceiveMessage call, until that window expires or the consumer explicitly calls ChangeMessageVisibility. Setting the value to 0 does not instantly redeliver currently-processing messages — only subsequent receives inherit the new value.
• Symmetric on Stop — restoring the original value on Stop does not retroactively fix the messages received during the attack: they keep the modified visibility window until their next receive. Allow a full receive-cycle after Stop before asserting on consumer behaviour.
• FIFO interaction — on FIFO queues, a short visibility timeout combined with a slow consumer can cause head-of-line blocking on the message group while the same message is redelivered. This is AWS-side behaviour and is the intended chaos signal, but worth noting when interpreting results.

Parameters

Parameter	Description	Default
Duration	How long the modified visibility timeout stays in effect.	60s
New visibility timeout (s)	New value in seconds. Valid range: 0-43200 (12 hours).	0