When learning Terraform, most tutorials start by creating new infrastructure.

But in the real world, companies already have infrastructure running in the cloud — and your job is to bring it under Terraform management without recreating or breaking anything.

That process is called:

Terraform Import

In this mini project we will:

• Create Azure infrastructure manually (outside Terraform)
• Make Terraform “discover” it
• Connect Terraform state to real resources
• Understand what Terraform actually manages

This tutorial focuses on understanding — not best practices, modules, or clean architecture.

Table of Contents

1. Step 0 — Create Infrastructure in Azure (Without Terraform)
2. Create Resource Group
3. Create Virtual Network and Subnet
4. Create App Service Plan (Free Tier)
5. Create Web App
6. Final Verification
7. Step 1 — Terraform Tries to Recreate Existing Resources
8. Step 2 — Connect Terraform to the Real Azure Resource
9. Verify Terraform Learned the Resource
10. The Most Important Test
11. What Just Happened?
12. Repeat for Other Resources
13. Key Concept You Must Understand
14. Final Result
15. What You Learned

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Step 0 — Create Infrastructure in Azure (Without Terraform)

We first create resources using Azure CLI so Terraform has no knowledge of them.

Resource Names

Resource	Name
Resource Group	rgcliminipro21212
Virtual Network	vnetcliminipro21212
App Service Plan	plancliminipro21212
Web App	webappcliminipro21212
Region	centralus

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Create Resource Group

az group create --name rgcliminipro21212 --location centralus

Verify:

az group show --name rgcliminipro21212 --query "{Name:name,Location:location}"

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Create Virtual Network and Subnet

az network vnet create --resource-group rgcliminipro21212 --name vnetcliminipro21212 --address-prefix 10.0.0.0/16 --subnet-name default --subnet-prefix 10.0.1.0/24

Verify VNet:

az network vnet show --resource-group rgcliminipro21212 --name vnetcliminipro21212 --query addressSpace.addressPrefixes

Verify Subnet:

az network vnet subnet show --resource-group rgcliminipro21212 --vnet-name vnetcliminipro21212 --name default --query addressPrefix

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Create App Service Plan (Free Tier)

az appservice plan create --name plancliminipro21212 --resource-group rgcliminipro21212 --sku F1 --is-linux

Verify:

az appservice plan show --name plancliminipro21212 --resource-group rgcliminipro21212 --query "{Tier:sku.tier,Name:sku.name}"

---

Create Web App

az webapp create --resource-group rgcliminipro21212 --plan plancliminipro21212 --name webappcliminipro21212 --runtime "NODE:18-lts"

Verify:

az webapp show --resource-group rgcliminipro21212 --name webappcliminipro21212 --query "{State:state,Host:defaultHostName}"

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Final Verification

az resource list --resource-group rgcliminipro21212 --output table

At this point:

Infrastructure exists in Azure
Terraform knows nothing about it

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Step 1 — Terraform Tries to Recreate Existing Resources

Create a file rg.tf

resource "azurerm_resource_group" "rg" {
  name     = "rgcliminipro21212"
  location = "centralus"
}

Run:

terraform plan

You will see:

Plan: 1 to add

Why?

Because Terraform has no memory yet — it only trusts the state file, not Azure.

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Step 2 — Connect Terraform to the Real Azure Resource

We now map the Terraform resource to the real resource.

Get Resource ID

az group show --name rgcliminipro21212 --query id --output tsv

Output looks like:

/subscriptions/<sub-id>/resourceGroups/rgcliminipro21212

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Import into Terraform

terraform import azurerm_resource_group.rg <RESOURCE_ID>

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Verify Terraform Learned the Resource

Check state

terraform state list

Inspect resource details

terraform state show azurerm_resource_group.rg

Terraform downloaded the real configuration from Azure.

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The Most Important Test

Run:

terraform plan

Now you should see:

No changes. Infrastructure matches configuration.

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What Just Happened?

Before import:

Terraform	Azure
Wants to create RG	RG already exists

After import:

Terraform	Azure
Knows RG exists	RG exists

Terraform did not create anything.
It only learned reality.

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Repeat for Other Resources

You repeat the same process for:

• Virtual Network
• Subnet
• App Service Plan
• Web App

The pattern never changes:

1. Write resource block
2. terraform plan → shows create
3. terraform import
4. terraform plan → shows no changes

You are teaching Terraform what already exists.

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Key Concept You Must Understand

Terraform does NOT manage infrastructure.

Terraform manages a state file.

If it is not in state → Terraform thinks it does not exist
If it is in state → Terraform controls it

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Final Result

After importing all resources:

You can now run:

terraform destroy

And Terraform will delete resources that were originally created manually.

That proves:

Terraform now owns the infrastructure

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What You Learned

• Terraform does not read Azure automatically
• Import does not create resources
• State file is the brain of Terraform
• Infrastructure can be adopted safely

This is one of the most important real-world Terraform skills.

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If you understood this concept, you now understand more Terraform than most beginners who only follow terraform apply tutorials.