Technical and Product News and Insights from Rackspace
Creating a VM in Azure by using Terraform with for loops
You can easily create multiple virtual machines (VMs) on Azure® by using Hashicorp® Terraform® with the help of Visual Studio® Code (VS Code).
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.
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
Log into Azure:
Check how many subscriptions we have for this tenant:
az account list --output table
Set the right subscription for our deployment:
az account set --subscription "XXXXXX-XXXXXXX-XXXX-XXX"
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):
Initialize Terraform in this directory:
Run the Terraform plan to check what we are going to build and save the plan output for later use by adding the
-outflag in the command:
terraform plan or terraform plan -out
Execute the Terraform code to deploy and type yes at the confirmation check or use
-auto-approveto skip manual confirmation:
terraform apply or terraform apply -auto-apply
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 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.
Have fun using Terraform for Azure and maintain standards with some simple code.
Use the Feedback tab to make any comments or ask questions.