docs(UPGRADE.md): update upgrade guide with detailed state migration …

…steps and verification process for EFS module upgrade

UPGRADE.md

@@ -10,8 +10,42 @@ This guide helps you upgrade the EFS module from version v0.3.5 and below to new
 
 ### Required Actions
 
-Before running `terraform plan`, you need to migrate the state of the EFS filesystem resource to prevent destruction and recreation. Execute the following command:
+1. First, create a backup of your terraform state:
 
 ```bash
-terraform state mv 'module.efs.module.efs.aws_efs_file_system.default[0]' 'module.efs.module.efs.aws_efs_file_system.this[0]'
+# For local state
+terraform state pull > terraform.tfstate.backup.$(date +%Y%m%d_%H%M%S)
 ```
+
+2. Before running `terraform plan`, you need to migrate the state of the EFS resources to prevent destruction and recreation. Execute the following commands in order:
+
+```bash
+# Move EFS file system
+terraform state mv 'module.efs.module.efs.aws_efs_file_system.default[0]' 'module.efs.module.efs.aws_efs_file_system.this[0]'
+
+# Move mount targets
+terraform state mv 'module.efs.module.efs.aws_efs_mount_target.default[0]' 'module.efs.module.efs.aws_efs_mount_target.this[0]'
+terraform state mv 'module.efs.module.efs.aws_efs_mount_target.default[1]' 'module.efs.module.efs.aws_efs_mount_target.this[1]'
+terraform state mv 'module.efs.module.efs.aws_efs_mount_target.default[2]' 'module.efs.module.efs.aws_efs_mount_target.this[2]'
+
+# Move file system policy
+terraform state mv 'module.efs.aws_efs_file_system_policy.default' 'module.efs.aws_efs_file_system_policy.this'
+
+# Move backup policy
+terraform state mv 'module.efs.module.efs.aws_efs_backup_policy.default[0]' 'module.efs.module.efs.aws_efs_backup_policy.policy[0]'
+
+### Verification Steps
+
+1. Run all the state move commands mentioned above
+2. Execute `terraform plan`
+3. Verify that the plan does not show destruction of any EFS resources
+4. The plan should only show changes related to the resource name changes
+5. If the plan shows EFS resource destruction, DO NOT APPLY and review the state migration steps
+
+### Notes
+
+- Always backup your Terraform state before performing any state migrations
+- Test these changes in a non-production environment first
+- If you encounter any issues during the upgrade, please refer to the module documentation or open an issue in the repository
+- Make sure to execute the state move commands in the order specified above
+- If you have a different number of mount targets, adjust the mount target migration commands accordingly