This post gives a walkthrough on how to migrate an RDS DB across two AWS accounts.

#1 Take Snapshot

• Take a snapshot of the target DB

Go to AWS --> RDS --> Snapshots --> Take snapshot

#2 Create a KMS key

• Create a fresh KMS key and share it with the target account

AWS --> KMS --> Customer-managed keys --> create key

• Before you go on creating the new key, don't skip the above step. Now proceed to enter the target account ID in the below field

• Create a snapshot (a second) of the snapshot created in #1. The reasoning for this is that the KMS key created in #2 which was shared with the target account, was done to allow the creation of the DB on the target account

select the snapshot --> action --> copy snapshot

• While the steps to copying are underway, select the freshly created KMS key (I named it "test") from the drop-down

#3 Share the Snapshot

• Share the copied snapshot with the target account and enter the target account ID, once more

Select the snapshot --> Action --> share snapshot

NOTE: The below-proceeding steps should be executed on the target account

#4 Create a New DB.

• The shared DB snapshot will show up in your target account

Go to AWS --> RDS --> Snapshot --> Shared with me

• In the target account, create a new DB instance by restoring the DB snapshot

RDS --> Snapshot --> Shared with me --> select snapshot --> action -->  restore snapshot.

NOTE: When creating a DB from the snapshot, DO NOT FORGET to swap the "test" KMS key with the "default" on the target account key. Select "(default) aws/rds"