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Creating a VM in Azure by using Terraform with for loops


You can easily create multiple virtual machines (VMs) on AzureĀ® by using HashicorpĀ® TerraformĀ® with the help of Visual StudioĀ® Code (VS Code).

Overview

This blog post focuses on bulk VM creation on Azure. I also emphasize the Infrastructure-as-Code (IaC) approach. I use VS Code throughout this blog, but you can use your favorite IDE.

Let’s get started

I went through the general requirements to create multiple VMs in Azure with some specific standard or typical nomenclature. Even when we build stuff on the fly, we have to keep an eagle eye on everything to sustain our standards. And maintaining the standard is not at all easy, mainly because we have to follow the same name canons for VM name, OS disk, data disk, network interface controller (NIC) name, and so on.

IaC lets us manage every aspect of maintaining standards, including things we build in the backend on the real surface.

I have written some simple Terraform code to create two VMs in Azure with similar names for every resource. I also use tags, which are the new way of segregating things. So, let’s straight jump into the action and get our hands dirty with Terraform.

Azure VM creation requires a resource group (RG), virtual network (VNet), subnet, NIC, and VM configuration. Keeping all that in mind, let’s make all the files separately so that it is easy to understand.

Create the resource group file

First, we need to create an RG code block in the Hashicorp configuration language (HCL). Let’s create two RGs (one for the VM and NIC and another for Networking stuff). As a best practice, I don’t recommend keeping everything together. Before creating the RGs, define a provider block for Terraform, so it understands that we are deploying Azure resources. Store this information for Terraform in a separate file called providers.tf:

The RG code, rg.tf:

Create the VNET and subnet files

Now, the second task is to create a VNet and a subnet for our VM.

The VNet block, vnet.tf:

And the subnet code, subnet.tf:

Create the NIC file

We are almost done with networking stuff except for our VM’s NIC. Let’s put the NIC code in the VM’s RG. Notice that I referenced the app RG in resource_group_name because keeping NIC details in the Network RG does not suit me.

The NIC code, Nic.tf:

Create the storage file

Now we are done with all the networking stuff, but most people consider a VM without diagnostic settings enabled to be a poor build. And I don’t want anyone to call me a “new builder”! Storage account code is simple, and by using that, we can call ourselves good Azure implementors.

The Storage account file, storage_account.tf:

Create the VM file

We are all set for VM code, but remember, we have to use the same standards that we used earlier, such as VM name, NIC name, disk name, and so on.

Final code for our VM, vm.tf:

Create the variable file

Finally, I put a few things into variables such as all the VM names. You can put other items into variables, such as RG, VNet, and subnet names. Using variables helps when you do giant builds.

The variable file, Variable.tf:

Build the VMs

My goal is to create two VMs by using a for loop. Thus, the vm_name variable has two VM names (you can add multiples), and the second variable is the location to which I want to deploy the Azure resources.

Let me share how I keep my standards intact: I used VMName-nic for every NIC, VMName-Osdisk, and -data1. All resources such as VM, NIC, and DISK pop up with the same nomenclature, thus, we can easily understand which resources belong to which VM.

Deploy

Let’s get down to business and learn how to deploy the VMs in Azure. It’s time to boil the eggs.

For simplicity, I use the Azure CLI for this task instead of using a proper DevOps approach and running this through a pipeline and storing the site files somewhere other than our directory.

If you don’t have the az CLI on your machine, you can install it.

  1. Log into Azure:

     az login
    
  2. Check how many subscriptions we have for this tenant:

     az account list --output table
    
  3. Set the right subscription for our deployment:

     az account set --subscription "XXXXXX-XXXXXXX-XXXX-XXX"
    
  4. Navigate to the directory where we have put our all Terraform code files (I used temp for this example, but I don’t recommend that location):

     cd 'C:\temp'
    
  5. Initialize Terraform in this directory:

     terraform init
    
  6. Run the Terraform plan to check what we are going to build and save the plan output for later use by adding the -out flag in the command:

     terraform plan
    
     or
    
     terraform plan -out
    
  7. Execute the Terraform code to deploy and type yes at the confirmation check or use -auto-approve to skip manual confirmation:

     terraform apply
    
     or
    
     terraform apply -auto-apply
    
  8. Check the VM that you created:

     az vm list -o table
    

Some secret for loop hacks

You can create multiple VMs by running a Terraform for loop as shown in the following code. The loop executes as many times as you defined the variable (twice, in our case, because I defined two VM names in the variable):

for_each = toset(var.vm_name)

The each object:

The for loop in Terraform has a key-pair, key and value, but both are generally similar.

In resource blocks, where you set for_each, you can use an additional each objects in your expressions to modify the configuration of each instance.

An each object has two attributes:

  • each.key: The map key (or set member) corresponding to this instance.

  • each.value: The map value corresponding to this instance. If you provided a set, this is the same as each.key.

You can use the Terraform fmt command to format the code, such as rewriting Terraform configuration files to conform to a canonical format and style. This command applies a subset of Terraform language style conventions, along with other minor adjustments for readability.

Conclusion

Have fun using Terraform for Azure and maintain standards with some simple code.

Use the Feedback tab to make any comments or ask questions.

post avatar
Gourav Kumar

An Azure professional, blog writer, and community contributor who is passionate about PowerShell, I’m also learning Terraform and forging my path to be on top.

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