Steps to Break Up a Terralith - Migration Script

github_repos_migration.sh

#!/bin/bash
###
### `github_repos_migration.sh` script purpose is to migrate the state to a new GitHub repositories root module.
### This script must be run from your root-modules directory, see below for the expected directory structure.
### └── root-modules
###            ├── terralith # legacy root module ($SRC_ROOT_MODULE)
###            └── github-repos # new root module ($DESTINATION_ROOT_MODULE)

set -eu -o pipefail

SRC_ROOT_MODULE="terralith"
DESTINATION_ROOT_MODULE="github-repos"
DATE=$(date +"%Y-%m-%d")
DESTINATION_STATE_FILE="github-repos-state-$DATE.tfstate"
SRC_STATE_FILE="terralith-state-$DATE.tfstate"

function mv_resource() {
    if ! tofu state mv -state-out="../$DESTINATION_ROOT_MODULE/$DESTINATION_STATE_FILE" "$1" "$1"; then
        echo "Check if the resource exists in the source state with: tofu state list | grep $1"
        exit 1
    fi
}

function main() {
    echo "⏳ Starting migration..."
    # Change into destination root module so we can pull state file and confirm initialized
    cd "$DESTINATION_ROOT_MODULE"
    tofu init

    # Pull the destination state into a local file so we can move resources to it
    tofu state pull > "$DESTINATION_STATE_FILE"

    # Confirm the source root module is initialized
    cd "../$SRC_ROOT_MODULE"
    tofu init

    # Pull the source state into a local file as a backup
    tofu state pull > "$SRC_STATE_FILE"

    # Move resources
     mv_resource "github_repository.foo"
     mv_resource "github_repository.bar"

    # Push the updated state file
    cd "../$DESTINATION_ROOT_MODULE"
    tofu state push "$DESTINATION_STATE_FILE"
    
    echo "Migration completed 🎉"
}

main