Using Parameter File With Bicep Templates

In the previous post we went through the process of deploying an Bicep template using parameter that where called directly from PowerShell.

This is ok when deploying resources that require only a few values to be set, but this can become difficult to manage when there are a lot of parameter like when deploying virtual machines or web apps.

A parameter file for Bicep is a json file that has the specific parameter names and values set.

I used this Microsoft document as a reference to create the parameter file.

https://docs.microsoft.com/en-us/azure/azure-resource-manager/bicep/parameter-files

Below is the Bicep file we create in the last post.

A parameter file for the storage Bicep template would look like the below.

Once we have the parameter file, we are ready to test the deployment. To test without actually deploying the resource add the whatif parameter.

New-AzResourceGroupDeployment -ResourceGroupName ResourceGroupName -TemplateFile .\BicepTemplate.bicep -TemplateParameterFile .\BicepParamter.json -WhatIf

Next we will create a template to deploy a virtual machine and it network interface. To create base template in visual studio code type

res-nic to populate the network interface:

Use res-vm-windows to populate the virtual machine.

I will be creating parameters for each part that requires customization and anything that doesn’t I will leave with the hardcode values like. The @descirpiton is a Parameter decorators that allow use to add a description of what the parameter is used for.

I create two variables for the vnetId and subnetref that are used for the network interface

Below is what the updated virtual machine resource template looks like.

Once we have the Bicep template file ready the next step is to configure the parameter file. I copied the default template file code from the above Microsoft document and added in each of the required parameters.

To get the virtual network ID that will be used in the parameters file go to the virtual network and click on properties > Resource ID.

Once we have that we can fill out the reset of the parameter values.

After the template file has been configured, we can test the deployment same way as the storage account and use the whatif to confirm there are no errors.

As I have not set the admin password in the template or parameter file the deployment will prompt for the admin password to be set on the VM.

If the test deployment comes back without any issues we can check the results from the whaif deployment to confirm all the are correct.

Since the template and parameter files have returned no error we are ready to run and deploy the new VM resource.

If we check the resource group the new VM, OSDisk and network interface should be created.

Now that we have all the template and parameter file working we can just create a new parameter file for each VM resource. We can now create fully customized VM’s pretty quickly instead of having to deploy using the Azure market place and manually select the options we want to set.

Deploy Azure Resource Using Bicep template and PowerShell

In a previous post we went through deploying resource using ARM templates. I have been recently working on creating some new templates to be used for additional deployment and decided to use Bicep templates instead as it seem to an easier and more straight forward way of writing template files to deploy resources in Azure.

Bicep uses a simpler syntax than creating templates using JSON, the syntax is declarative and specifies which resources and resource properties you want to deploy.

Below is a comparison of a JSON and Bicep template file to create a storage account.

We can see that the bicep file is an easier format to read and create.

JSON Template
Bicep Template

To get started with Bicep we will first be installing the Bicep extension to Visual Studio Code so we can edit and modify Bicep templates.

The extension adds intellisense which makes it easier than looking up the full syntax for each resource.

To create a new template click on new file in VS code and select bicep as the language.

To create a template using intellisense either start typing the res-resource type or the resource type itself.

Click on the resource to pre populate the template.

The values can be hard code in the template file but this would require manual change each time the template is run.

We can add parameters to the template to make it more reusable. There are a few different types of parameters that can be used.

Below is a brief description of each type.

ParameterDescription
stringSingle line value
arrayAllow multiple values
intInteger value
boolRequired true or false
objectsAllows property types

Microsoft have a more in depth document on the different data types.

https://docs.microsoft.com/en-us/azure/azure-resource-manager/bicep/data-types

The below is an example of a template with parameters set.

Once we have the template we need to install Azure PowerShell if not already installed and to install the Bicep tools, below is the document to install.

https://docs.microsoft.com/en-us/azure/azure-resource-manager/bicep/install#install-manually

To connect to Azure PowerShell use

Connect-AzAccount

Once connected we can use the New-AzResourceGroupDeployment to deploy the template and specify the parameters values. To test the deployment for errors without running an actual deployment we can use the -whatif parameter.

New-AzResourceGroupDeployment -ResourceGroupName ResourceGroup -TemplateFile pathtotempaltefile\BicepStorageTest.bicep -location regsion -storagename storageaccountname -storagetype Standard_LRS -WhatIf

Run the command and it should return any error if there is an issue or green if there is no issue.

Once the template comes back with no issues we can remove the -whatif and the storage account will be created.

To confirm the storage account has been created use the Get-AzStorageAccount

Using parameters in the Bicep template is fine when there are only a few that need to be called but for more complex deployment it will be better to use a parameters file and pre fill each value.

In the next post we will go through the process of using a template to create a VM and its network interface and will call a parameters files instead of call the parameters in PowerShell directly.