DMS migration task failing to connect to S3

Question

We have a DMS migration task that has been successfully running for months. Recently, it started failing. We've tried restarting and recreating the task, but it continues to fail. It looks like the failures are related to an S3 connection issue. We even tried deleting the default S3 bucket that is created and used by the DMS migration task, and then creating a new task that recreated the S3 bucket. Here is a sample of the errors that we are seeing in the DMS migration task logs.

2023-08-01T17:45:20 [SOURCE_CAPTURE ]E: Failed to list bucket 'dms-x-prod-redshift': error code <>: curlCode: 7, Couldn't connect to server [1001713] (s3_dir_actions.cpp:105)

2023-08-01T17:45:20 [SOURCE_CAPTURE ]I: Failed to list bucket 'dms-x-prod-redshift' (s3_dir_actions.cpp:209)

2023-08-01T17:45:20 [SOURCE_CAPTURE  ]E:  Failed to list bucket 'dms-x-prod-redshift': error code <>: curlCode: 7, Couldn't connect to server [1001713]  (s3_dir_actions.cpp:105)

2023-08-01T17:45:20 [SOURCE_CAPTURE  ]I:  Failed to list bucket 'dms-x-prod-redshift'  (s3_dir_actions.cpp:209)

Accepted Answer

Is your DMS connected to a subnet in your VPC which

1. doesn’t have a route to the internet via a NAT gateway
2. is in a public subnet without a public IP
3. Have a S3 gateway and can’t route via it.

The DMS if attaching to the VPC will need to be able resolve and connect to the S3 endpoint.

Answer

Make sure you have ephemeral ports open if a private subnet behind NAT!!

https://docs.aws.amazon.com/vpc/latest/userguide/vpc-network-acls.html#nacl-ephemeral-ports

DMS migration task failing to connect to S3

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