How to Create Azure Function App using Terraform ?

Last Updated : 30 Apr, 2024

Azure function app is a serverless implementation that provides execution of code without worrying about underlying infrastructure in Azure. It allows to writing of code in small functions called Azure functions which can be triggered using events in the Azure cloud. In this article let’s see how we can create a Azure function app using Terraform.

Understanding Of Primary Terminologies

The following are the primary components of Azure Vnet related to Terraform:

Terraform: It is Infrastructure as an infrastructure-as-a-service tool that allows the deployment of resources to multiple cloud providers through code.
Azure Function App: In Microsoft Azure, a function app is a serverless component that allows the execution of code without provisioning reserved infrastructure.
IaaC: Infrastructure as a Code allows the representation of cloud infrastructure in the form of code.

Setup Azure Function App Using Terraform: A Step-By-Step Guide

Step 1: Set Up Terraform

Download the Terraform zip from the installation page of the Terraform website.
Extract and paste the terraform folder to the required location and add the path to runnable in environment variables.
For MacOs install the terraform using HomeBrew.

Step 2: Set Up Azure CLI

Download the Azure CLI setup from the official website.
Run the installer and follow the steps to install.

Azure CLI

For MacOs install the Azure CLI using below HomeBrew Command.

brew update && brew install azure-cli

Step 3: Configure Azure CLI

Open terminal and run below command.

az login

A browser window will open for login. Login with your azure credentials. Once it is done you will see output as below.

Configuring Azure CLI

Step 4: Create Terraform Code

Goto your project folder and create main.tf file.
Add terraform block to code with azure as required provider with latest version. You can find the latest version at hashicorp registry.

Terraform block should look like below. You can add required version to avoid invalidation.

terraform {
  required_providers {
    azurerm = {
        source = "hashicorp/azurerm"
        version = "~>3.0"
    }
  }
}

Now add provider as azurerm like below. Specify other details as required.

provider "azurerm" {
  features {}
}

Before creating function app we must create storage account and app service plan. To create storage account add configuration as below.

resource "azurerm_storage_account" "deepslabteststorageacc" {
  name = "deepslabteststorageacc"
  resource_group_name = "DeepsLab"
  location = "eastus"
  account_tier = "Standard"
  account_replication_type = "LRS"
}

Here we have mentioned account tier and replication type for storage account. Now add configuration for app service plan.

resource "azurerm_service_plan" "deepslabserviceplan" {
  name = "deepslabserviceplan"
  resource_group_name = "DeepsLab"
  location = "eastus"
  os_type = "Linux"
  sku_name = "Y1"
}

The os type and SKU name has to be provided for service plan as mentioned above.
Finally add configuration for function app. For this article we will add only required arguments and use linux function app. You can specify other arguments if required.

resource "azurerm_linux_function_app" "deepslabtestfunctionapp" {
  name = "deepslabtestfunctionapp"
  resource_group_name = "DeepsLab"
  location = "eastus"
  storage_account_name = azurerm_storage_account.deepslabteststorageacc.name
  storage_account_access_key = azurerm_storage_account.deepslabteststorageacc.primary_access_key
  service_plan_id = azurerm_service_plan.deepslabserviceplan.id
  depends_on = [ azurerm_service_plan.deepslabserviceplan , azurerm_storage_account.deepslabteststorageacc ]
  site_config {}
}

We have specified name for function app. We have specified the location and resource group where virtual network should be created.
we have added storage account properties and service plan added earlier. We must add depends on so that storage account and service plan is created earlier.
The complete code will look like below.

terraform {
  required_providers {
    azurerm={
        source = "hashicorp/azurerm"
        version = "~>3.0"
    }
  }
}

provider "azurerm" {
  features {}
}

resource "azurerm_storage_account" "deepslabteststorageacc" {
  name = "deepslabteststorageacc"
  resource_group_name = "DeepsLab"
  location = "eastus"
  account_tier = "Standard"
  account_replication_type = "LRS"
}

resource "azurerm_service_plan" "deepslabserviceplan" {
  name = "deepslabserviceplan"
  resource_group_name = "DeepsLab"
  location = "eastus"
  os_type = "Linux"
  sku_name = "Y1"
}

resource "azurerm_linux_function_app" "deepslabtestfunctionapp" {
  name = "deepslabtestfunctionapp"
  resource_group_name = "DeepsLab"
  location = "eastus"
  storage_account_name = azurerm_storage_account.deepslabteststorageacc.name
  storage_account_access_key = azurerm_storage_account.deepslabteststorageacc.primary_access_key
  service_plan_id = azurerm_service_plan.deepslabserviceplan.id
  depends_on = [ azurerm_service_plan.deepslabserviceplan , azurerm_storage_account.deepslabteststorageacc ]
  site_config {}
}

Step 5: Apply The Terraform Code

Once the code is ready you can apply it.
First init the terraform by running below command in project folder where main.tf is present.

terraform init

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After successful output of terraform apply the changes using below command.

terrraform apply

After verifying type “yes” to confirm and apply.

Terraform will start creating network.

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You can also verify deployment by visiting Virtual Networks page of Azure.

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Conclusion

We have successfully created Azure Function app with the help of terraform in this article. the configuration described can be further modified to make changes to OS type and function runtime in azure. This is how terraform allows reusable and modifiable configuration of infrastructure.