Terraform: How to migrate state between projects?

Question

What is the least painful way to migrate state of resources from one project (i.e., move a module invocation) to another, particularly when using remote state storage? While refactoring is relatively straightforward within the same state file (i.e., take this resource and move it to a submodule or vice-versa), I don't see an alternative to JSON surgery for refactoring into different state files, particularly if we use remote (S3) state (i.e., take this submodule and move it to another project).

Answer 1

The least painful way I’ve found is to pull both remote states local, move the modules/resources between the two, then push back up. Also remember, if you’re moving a module, don’t move the individual resources; move the whole module.

For example:

cd dirA terraform state pull > ../dirA.tfstate  cd ../dirB terraform state pull > ../dirB.tfstate  terraform state mv -state=../dirA.tfstate -state-out=../dirB.tfstate module.foo module.foo  terraform state push ../dirB.tfstate  # verify state was moved terraform state list | grep foo  cd ../dirA terraform state push ../dirA.tfstate 

Unfortunately, the terraform state mv command doesn’t support specifying two remote backends, so this is the easiest way I’ve found to move state between multiple remotes.