TL;DR: It’s possible, however dangerous. Do it in case you already f*cked up really need it.

Note: It may be safer and faster to terraform state rm and terraform state import, for small changes. This article can have mistakes.

A state is just a JSON file, usually stored in a cloud. You should never edit .tfstate files manually. Use terraform provided commands instead.

How to

Preparation (safe)

terraform state pull would fetch state from remote storage and output it as STDOUT. If you use remote state, local file would be empty.

Fetch state

# Here we put evetyrhing into home folder
# cd ~/tf/source_dir
terraform state pull > ~/source.tfstate
# cd ~/tf/destination_dir
terraform state pull > ~/destination.tfstate

Now we have two backuped states. No risks so far.

Doublecheck exported state files

To avoid any conflicts with remote backend, use different folder.

terraform state list -state=~/source.tfstate # | grep 'mysupermodule'
terraform state list -state=~/destination.tfstate

Move state between backups (safe)

The following command does not change the infrastructure. Here we would move JSON state between local files (no errors expected).

# terraform state mv [options] SOURCE DESTINATION
# where options are `-state` and `-state-out`; Also `-lock=false` may be required 
terraform state mv -state=~/source.tfstate -state-out=~/destination.tfstate module.api.module.mysupermodule module.mysupermodule

Doublecheck states again. If the result is unexpected, start from the beginning.

terraform state list -state=~/source.tfstate # | grep 'mysupermodule'
terraform state list -state=~/destination.tfstate

Update sources (safe)

Create/delete modules and resources to reflect same changes.

Optional check for paranoid (kinda safe)

I’m scared, show it anyway!

With local backend only P3 is required. But with remote backend -state flag can not be used, so

  1. Edit backend in source code:
terraform {
  required_version = "~> 0.14.0"
  # Comment any remote backend definition
  # backend "s3" {
  #   bucket = "here-i-store-my-states"
  #   key    = "example/terraform.tfstate"
  # }

  # Add local backend with path state you want to test
  backend "local" {
    path = "~/source.tfstate"
  1. Then init terraform. It would ask if you want to move state, answer No.
terraform init # Don't move the state
  1. Now having local backend we can specify -state flag. (P3)
terraform plan -state=~/source.tfstate -refresh=false
  1. Undo changes made in step 1 and init terraform again

Apply changes (dangerous)

If everything is as you expected, we need to push state. (always do backups)

# cd ~/tf/source_dir
terraform state push ~/source.tfstate
# cd ~/tf/destination_dir
terraform state push ~/destination.tfstate

Check results with terraform plan in respective directories.

Do not forget to commit and push the code.