56_1: Introduction:

This Terraform script clones an existing OCI instance by referencing its configuration, such as shape, image, and network settings.

56_2: Terraform Configuration

56_2_1: Create Terraform Directory

Open the code editor in OCI and create a folder named 'terraform'.

56_2_2: Create Terraform File

Create a new file named Import.tf in this folder. .tf is the extension of terrraform file.

56_2_3: Import the Instance into Terraform State

Put the below command in this Import.tf file and will replace with OCI ID of Existing Instance.

import {
id = "ocid.virtual_circuit.oc1.phx.example"
to = oci_core_virtual_circuit.test_virtual_circuit
}

Explanation: id = "ocid1.instance.oc1.phx.example" → This is the OCID of the existing instance you are copying.

to = oci_core_instance.new_instance → This is the Terraform resource that will manage the copied instance.

Copy the OCI ID of the existing Instance and replace it in this command in the value for id= .

Put the oci_core_instance.test_instance in the value for to= .

import {
id = "ocid1.instance.oc1.iad.anuwcljtl6qj5oyczl2zxp4igbiuexaciprf3bhyn5eniybjzvrkw747lq7a"
to = oci_core_instance.test_instance
}

56_2_4: Open Integrated Terminal

Now, Right click on import.tf file and select open in integrated terminal.

56_2_5. Initialize Terraform.

terraform init

Terraform is initialized now.

56_2_6. Generate Terraform Configuration

terraform plan --generate-config-out=generated.tf

This will create a generated.tf file with the current configuration of the imported instance.

A new file named generated.tf is created with execution plan.

56_2_7: Comment Out Import File

By placing a # before the import.tf command in the code editor, it is converted into a comment. This prevents the command from being executed, effectively hiding it from the execution process.

56_2_8: Create New Terraform File

Now we will create a New File in the Terraform for the new instance and name it.

Create a new Terraform file for the new instance and name it Application_Server.tf.

56_2_9: Copy Configuration to New File.

Copy all from generated.tf

Paste into Application_Server.tf

Place # into generated.tf to make it inactive and will be treated as comment. In another way, multi-line comments are enclosed within /* ... */ to make it inactive and to be treated as comment.

Now, generated.tf is comment only and will not be executed.

56_2_10: Run Terraform Plan

Run the Terraform plan command to preview the changes

terraform plan 

56_2_11: Apply Terraform Configuration

Review all details and apply the Terraform plan

terraform apply

Now, enter Yes to confirm and apply the plan.

56_2_12: Troubleshoot Errors

Error Correction

Error 1: 400-InvalidParameter, Invalid Nvmes: 1

Solution: Comment out nvmes = 1 in shape_config as VM.Standard.E3.Flex does not support NVMe storage.

Error 2: 400-InvalidParameter, Hostname Application_Server is provided when AssignPrivateDnsRecord is false.

Solution: Remove or comment out hostname_label since private DNS is disabled.

Error 3: 400-InvalidParameter, Requested volume size 47GB is not in the allowed range.

Solution: Update boot_volume_size_in_gbs to at least 50GB

56_2_13: Instance Creation

Now Creating.

Instance is created now.

56_2_14: Terminate the Instance.

terraform destroy

Instance has been destroyed.

56_3: Conclusion

This guide provides a step-by-step approach to cloning an OCI instance using Terraform. It covers Terraform initialization, importing an instance, troubleshooting errors, and deploying an instance. Following these steps ensures a smooth replication of an existing instance with the necessary configurations.