tfscp (terraform state copy)

tfscp is a tool designed for migrating Terraform resources across remote states. It simplifies the process by leveraging Terraform's existing capabilities.

How it works

tfscp automates the following steps:

1. Creates a temporary operating directory.
2. Validates that terraform init succeeds in both source and target state directories.
3. Downloads the source and target states locally.
4. Uses terraform state mv to move the specified resource from the source to the target state.
5. Pushes the updated target state back to the remote location using terraform state push.
6. Cleans up the temporary operating directory.

Installation

To install tfscp, run the following commands:

wget https://github.com/thomasv314/tfscp/releases/download/v1.0.2/tfscp-darwin-amd64
mv tfscp-darwin-amd64 /usr/local/bin/tfscp
chmod u+x /usr/local/bin/tfscp

Usage

Usage:
  tfscp [terraform resource address] [flags]

Flags:
      --dry-run             If true, do not actually move the resource (default true)
  -h, --help                help for tfscp
      --source-dir string   Source directory to move a terraform resource from (optional, defaults to CWD)
      --target-dir string   Target directory to move a terraform resource to

Example scenario

Suppose you have the following Terraform states:

└── apps
    ├── applications.tf
    ├── config.tf       # Uses s3://terraform-states/apps.tfstate
    └── foobar-service
        ├── config.tf   # Uses s3://terraform-states/foobar-service.tfstate
        └── service.tf 
2 directories, 4 files

Here, the apps directory contains a module for your app: module.foobar_service.

By default, tfscp operates in a safe "dry-run" mode. To preview actions, run tfscp from the source directory:

tfscp "module.foobar_service" --target-dir="./foobar-service"

For example:

If the dry-run output looks good, execute the migration by disabling the dry-run mode:

 tfscp "module.foobar_service" --target-dir="./foobar-service" --dry-run=false