🆕 Linking Stacks and Databases

[jamie-lynch]

A number of applications rely on databases for persistence. Currently, there are multiple approaches for cloud-forming the two components and allowing the related security groups to talk to each other.

Two example approaches are:

1. Configure the database and ASG in the same stack

   This makes linking the two really easy. It does increase the risk that a change to the stack may have an effect on the
   database but adding removal protection goes some way to mitigating this risk.

2. Use parameters to provide the security group ids to each stack

   This approach allows the persistence layer to be defined in its own stack. The ASG and DB security group ids are then
   provided to each stack via parameters. This does mean that if the ID of one security group changes, the other stack
   also has to be updated (and won't work in the meantime). It also means that at creation time, there are a few steps to get
   everything setup as both groups must exist before they can refer to each other.

Are there any other solutions to this problem and can we standardise on one of them?