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https://github.com/ishuar/terraform-state-migration

Tutorial : How to migrate terraform state ?
https://github.com/ishuar/terraform-state-migration

Last synced: 20 days ago
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Tutorial : How to migrate terraform state ?

Host: GitHub
URL: https://github.com/ishuar/terraform-state-migration
Owner: ishuar
Created: 2022-09-05T22:06:29.000Z (about 2 years ago)
Default Branch: main
Last Pushed: 2022-09-18T16:01:53.000Z (about 2 years ago)
Last Synced: 2024-10-13T02:08:49.253Z (about 1 month ago)
Size: 191 KB
Stars: 0
Watchers: 2
Forks: 0
Open Issues: 1
Metadata Files:
- Readme: README.md
- Codeowners: .github/CODEOWNERS

Awesome Lists containing this project

README

- [Tutorial : How to migrate terraform state ?](#tutorial--how-to-migrate-terraform-state-)
- [Moving State file from remote file to another remote **empty** file.](#moving-state-file-from-remote-file-to-another-remote-empty-file)
- [Initial Backend Configuration](#initial-backend-configuration)
- [First Terraform apply after resource definition. [ Old State ]](#first-terraform-apply-after-resource-definition--old-state-)
- [Pull Terraform State](#pull-terraform-state)
- [To verify if the remote state is still in use.](#to-verify-if-the-remote-state-is-still-in-use)
- [Update the new backend configuration.](#update-the-new-backend-configuration)
- [Init with `-reconfigure` flag.](#init-with--reconfigure-flag)
- [Move Local Pulled State to New State.](#move-local-pulled-state-to-new-state)
- [Verify if the resources are still available with new state file.](#verify-if-the-resources-are-still-available-with-new-state-file)
- [Clean up local and Old State File.](#clean-up-local-and-old-state-file)

# Tutorial : How to migrate terraform state ?

In this tutorial I have used azurerm storage account as a remote backend, however it should be same in other hyperscaler or other backend. Please refer to respective backend configuration documentation.

## Moving State file from remote file to another remote **empty** file.

#### Initial Backend Configuration

```hcl
terraform {
required_providers {
azurerm = {
source = "hashicorp/azurerm"
version = "~>3.21"
}
}
backend "azurerm" {
resource_group_name = "resource_group_with_storage_account"
storage_account_name = "uniquestorageaccount"
container_name = "tfstates"
key = "statemigration-dir1.tfstate"
}
}
```

#### First Terraform apply after resource definition. [ Old State ]

```hcl
Plan: 4 to add, 0 to change, 0 to destroy.

Changes to Outputs:
+ rg_name = "state-migration"
+ vpc_name = "vnet-state-migration"
azurerm_resource_group.this: Creating...
azurerm_resource_group.this: Creation complete after 1s [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration]
azurerm_network_security_group.this: Creating...
azurerm_storage_account.this: Creating...
azurerm_network_security_group.this: Creation complete after 5s [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration/providers/Microsoft.Network/networkSecurityGroups/sg-state-migration]
azurerm_virtual_network.this: Creating...
azurerm_storage_account.this: Still creating... [10s elapsed]
azurerm_virtual_network.this: Creation complete after 5s [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration/providers/Microsoft.Network/virtualNetworks/vnet-state-migration]
azurerm_storage_account.this: Still creating... [20s elapsed]
azurerm_storage_account.this: Creation complete after 28s [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration/providers/Microsoft.Storage/storageAccounts/stmigrstgacct]

Apply complete! Resources: 4 added, 0 changed, 0 destroyed.

Outputs:

rg_name = "state-migration"
vpc_name = "vnet-state-migration"
```

#### Pull Terraform State

```bash
terraform state pull > local.tfstate
```

- It will pull the remote state file locally under `local.tfstate` file.

##### To verify if the remote state is still in use.

```bash
➜ terraform-state-migration git:(docs/state-migrate) ✗ tf plan
azurerm_resource_group.this: Refreshing state... [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration]
azurerm_network_security_group.this: Refreshing state... [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration/providers/Microsoft.Network/networkSecurityGroups/sg-state-migration]
azurerm_storage_account.this: Refreshing state... [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration/providers/Microsoft.Storage/storageAccounts/stmigrstgacct]
azurerm_virtual_network.this: Refreshing state... [id=/subscriptions/xxxxxxxxx-xxxx-4c3d-b7ae-xxxxxxxxx/resourceGroups/state-migration/providers/Microsoft.Network/virtualNetworks/vnet-state-migration]

No changes. Your infrastructure matches the configuration.

Terraform has compared your real infrastructure against your configuration and found no differences, so no changes are needed.
```

#### Update the new backend configuration.

```hcl
terraform {
required_providers {
azurerm = {
source = "hashicorp/azurerm"
version = "~>3.21"
}
}
backend "azurerm" {
resource_group_name = "CDT-ishan-test"
storage_account_name = "backendstorageacct"
container_name = "tfstates"
key = "statemigration-dir2.tfstate" # "now is dir2 in key"
}
}
```

> **Info:** if you run `terraform init` at this time it will give you an error `"Error: Backend configuration changed"`.

##### Init with `-reconfigure` flag.

To reconfigure the tf state to new one use the below command.

```bash
terraform init -reconfigure
```

> At this time if you run `terraform plan` it should tell you to create all resources again.

#### Move Local Pulled State to New State.

To Push terraform local state which we pulled in above steps to new state file use the following command.

```bash
tf state push local.tfstate
```

#### Verify if the resources are still available with new state file.

Run `terraform plan` to verify if the resources are still available with new state file.

No changes. Your infrastructure matches the configuration.

Terraform has compared your real infrastructure against your configuration and found no differences, so no changes are needed.
```

#### Clean up local and Old State File.

- Remove the localy pulled state file.

```bash
rm local.tfstate
```

- Browse to your remote backend (s3 or storageAccounts) and then remove the state file.

Reference screenshot after deleting the first state file.
![image](./tf-state-migration.png "Remote Backend Status")