📌 Steps to Migrate Terraform State

✅ 1. Backup the Current State

Before making any changes, it’s always good practice to backup the current state:

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terraform state pull > terraform.tfstate.backup

This ensures we have a snapshot of the existing state, just in case anything goes wrong.

🛠️ 2. Create a New GCS Bucket

Next, I created a new Google Cloud Storage (GCS) bucket to store the Terraform state:

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gsutil mb gs://NEW_BUCKET_NAME

📂 3. Copy the State File to the New Bucket

Once the bucket was ready, I copied the existing Terraform state file from the old bucket to the new one:

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gsutil cp -r gs://SOURCE_BUCKET_NAME/* gs://DESTINATION_BUCKET_NAME

📝 4. Update the Backend Configuration

Now, I updated the Terraform backend configuration in main.tf to point to the new bucket:

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terraform {
  backend "gcs" {
    bucket = "NEW_BUCKET_NAME"
    prefix = "terraform/state"
  }
}

🔄 5. Migrate the State

To finalize the migration, I ran the following command:

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terraform init -migrate-state

Terraform automatically detected the change in backend configuration and migrated the state to the new bucket.

🔍 Verifying the Migration

After migrating the state, I performed several verification steps to ensure everything was intact.

🧐 1. Check the New State File

Pulled the new state file to compare with the old one:

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terraform state pull > new_state.tfstate

🔍 2. Compare Old and New State Files

Checked if there were any unexpected changes:

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diff terraform.tfstate.backup new_state.tfstate

🔄 3. Run a Plan to Ensure No Drift

To confirm the migration didn’t introduce unintended changes, I ran:

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terraform plan

✅ Expected Outcome: The terraform plan should show no changes, confirming that everything migrated successfully.

🛡️ Safety Checks

To ensure the integrity of the migration, I followed these best practices:

• Plan should show no changes after migration ✅
• State list should match before & after migration ✅
• Diff between state files should be minimal (only backend config changes) ✅

🎉 Conclusion

Migrating Terraform state can seem risky, but by following a structured approach and verifying each step, you can ensure a smooth transition without disrupting your infrastructure.

If you ever need to migrate your Terraform state, remember:

💡 Backup first

💡 Verify integrity after migration

💡 Run a terraform plan to detect any unintended changes