Terraform Init throwing error while using with Azure DevOps

I am trying to run Terraform Open Source using Azure Devops I have the state file stored in Azure Blobstorage

Below is my pipeline file

variables:
  - group: infra-variables
  
trigger:
  branches:
    include:
    - master
  paths:
    include:
    - Terraform-Test 
    exclude:
    - README.md
  
stages:
- stage: Validate
  displayName: Validate
  jobs:
  - job: validate
    pool:
      vmImage: ubuntu-latest
    steps:
    - task: ms-devlabs.custom-terraform-tasks.custom-terraform-installer-task.TerraformInstaller@0
      displayName: Install Terraform
      inputs:
        terraformVersion: 'latest'

  # Init
    - task: TerraformCLI@0
      displayName: Initialize Terraform
      env:
        ARM_SAS_TOKEN: $(ARM_ACCESS_KEY)
      inputs:
        command: 'init'
        workingDirectory: '$(System.DefaultWorkingDirectory)/Terraform-Test'
        commandOptions: '-backend-config=storage_account_name=$(TF_STATE_BLOB_ACCOUNT_NAME) -backend-config=container_name=$(TF_STATE_BLOB_CONTAINER_NAME) -backend-config=key=$(ARM_ACCESS_KEY)'
        backendType: 'selfConfigured'

  # Validate
    - task: TerraformCLI@0
      displayName: Validate Config
      inputs:
        command: 'validate'
        workingDirectory: '$(System.DefaultWorkingDirectory)/Terraform-Test'

- stage: Plan
  displayName: Plan
  jobs:
  - job: plan
    pool:
      vmImage: ubuntu-latest
    steps:
    - task: ms-devlabs.custom-terraform-tasks.custom-terraform-installer-task.TerraformInstaller@0
      displayName: Install Terraform
      inputs:
        terraformVersion: 'latest'

  # Init
    - task: TerraformCLI@0
      displayName: Initialize Terraform
      env:
        ARM_SAS_TOKEN: $(ARM_ACCESS_KEY)
      inputs:
        command: 'init'
        workingDirectory: '$(System.DefaultWorkingDirectory)/Terraform-Test'
        commandOptions: '-backend-config=storage_account_name=$(TF_STATE_BLOB_ACCOUNT_NAME) -backend-config=container_name=$(TF_STATE_BLOB_CONTAINER_NAME) -backend-config=key=$(ARM_ACCESS_KEY)'
        backendType: 'selfConfigured'

  # Plan
    - task: TerraformCLI@0
      displayName: Plan Terraform Deployment
      env:
        ARM_SAS_TOKEN: $(ARM_ACCESS_KEY)
        ARM_CLIENT_ID: $(AZURE_CLIENT_ID)
        ARM_CLIENT_SECRET: $(AZURE_CLIENT_SECRET)
        ARM_SUBSCRIPTION_ID: $(AZURE_SUBSCRIPTION_ID)
        ARM_TENANT_ID: $(AZURE_TENANT_ID)
      inputs:
        command: 'plan'
        workingDirectory: '$(System.DefaultWorkingDirectory)/Terraform-Test'

# Approve
- stage: Approve
  displayName: Approve
  jobs:
  - job: approve
    displayName: Wait for approval
    pool: server
    steps: 
    - task: ManualValidation@0
      timeoutInMinutes: 60
      inputs:
        notifyUsers: 'pallabcd@hotmail.com'
        instructions: 'Review the plan in the next hour'

- stage: Apply
  displayName: Apply
  jobs:
  - job: apply
    pool:
      vmImage: ubuntu-latest
    steps:
      - task: ms-devlabs.custom-terraform-tasks.custom-terraform-installer-task.TerraformInstaller@0
        displayName: Install Terraform
        inputs:
          terraformVersion: 'latest'
      
      # Init
      - task: TerraformCLI@0
        displayName: TF Init 
        env:
          ARM_SAS_TOKEN: $(ARM_ACCESS_KEY)
        inputs:
          command: 'init'
          workingDirectory: '$(System.DefaultWorkingDirectory)/Terraform-Test'
          commandOptions: '-backend-config=storage_account_name=$(TF_STATE_BLOB_ACCOUNT_NAME) -backend-config=container_name=$(TF_STATE_BLOB_CONTAINER_NAME) -backend-config=key=$(ARM_ACCESS_KEY)'
          backendType: 'selfConfigured'


      # Apply
      - task: TerraformCLI@0
        displayName: TF Apply 
        env:
          ARM_SAS_TOKEN: $(ARM_ACCESS_KEY)
          ARM_CLIENT_ID: $(AZURE_CLIENT_ID)
          ARM_CLIENT_SECRET: $(AZURE_CLIENT_SECRET)
          ARM_SUBSCRIPTION_ID: $(AZURE_SUBSCRIPTION_ID)
          ARM_TENANT_ID: $(AZURE_TENANT_ID)
        inputs:
          command: 'apply'
          workingDirectory: '$(System.DefaultWorkingDirectory)/Terraform-Test'
          commandOptions: '-auto-approve'

My main.tf file is given below

terraform {
  required_version = "开发者_JAVA技巧~> 1.0"

  backend "azurerm" {
  storage_account_name = var.storage_account_name
  container_name = var.container_name
  key = "terraform.tfstate"
  access_key = "#{ARM_ACCESS_KEY}#"
  features {}
}
  
  required_providers {
    azuread = "~> 1.0"  
    azurerm = "~> 2.0"
  }
  }


provider "azurerm" {
  tenant_id       = var.tenant_id
  client_id       = var.client_id
  client_secret   = var.client_secret
  subscription_id = var.subscription_id
  features {}
}

data "azurerm_resource_group" "az-rg-wu" {
  name = "Great-Learning"
}

data "azurerm_client_config" "current" {}

When i am putting the actual storage access key in main.tf the Init is successful but if i am putting the ADO variable in the form of "#{ARM_ACCESS_KEY}#", the pipeline fails. This variable is there in my tfvar file also and the value is set in a variable group in Azure Devops

So what i am doing wrong here

The service connection may cause problems. Terraform should require a proper service connection and an Azure DevOps extension as a pre-requisite. Ensure Terraform CLI is installed on the pipeline agent.

Here is the sample YAML to connect to Azure DevOps.

Step1: sample yaml file code as below

variables: 
 - name: TerraformBackend.ResourceGroup
   value: rg-realworld-staging-001
 - name: TerraformBackend.StorageAccount
   value: strwstagingterraform01
 - name: TerraformBackend.ContainerName
   value: staging
 - group: 'staging'

steps:
- task: AzureCLI@2
  inputs:
    azureSubscription: '[service connection]'
    scriptType: 'bash'
    scriptLocation: 'inlineScript'
    inlineScript: |
      az group create --location eastus --name $(TerraformBackend.ResourceGroup)
      az storage account create --name $(TerraformBackend.StorageAccount) --resource-group $(TerraformBackend.ResourceGroup) --location eastus --sku Standard_LRS
      az storage container create --name staging --account-name $(TerraformBackend.StorageAccount)
      STORAGE_ACCOUNT_KEY=$(az storage account keys list -g $(TerraformBackend.ResourceGroup) -n $(TerraformBackend.StorageAccount) | jq ".[0].value" -r)
      echo "setting storage account key variable"
      echo "##vso[task.setvariable variable=ARM_ACCESS_KEY;issecret=true]$STORAGE_ACCOUNT_KEY"


- task: TerraformInstaller@0
  inputs:
    terraformVersion: '1.3.6'

- task: TerraformTaskV1@0
  displayName: "Terraform Init"
  inputs:
    provider: 'azurerm'
    command: 'init'
    backendServiceArm: '[service connection]'
    backendAzureRmResourceGroupName: $(TerraformBackend.ResourceGroup)
    backendAzureRmStorageAccountName: $(TerraformBackend.StorageAccount)
    backendAzureRmContainerName: '$(TerraformBackend.ContainerName)'
    backendAzureRmKey: 'infrastructure/terraform.tfstate'
    workingDirectory: '$(System.DefaultWorkingDirectory)/stag/'



- task: TerraformTaskV1@0
  displayName: "Terraform Apply"
  inputs:
    provider: 'azurerm'
    command: 'apply'
    workingDirectory: '$(System.DefaultWorkingDirectory)/stag/'
    environmentServiceNameAzureRM: '[service connection]'
    commandOptions: |
      -var "some_key=$(value)"

Upon init execution

Updated main tf file as below

terraform {
  required_version = "~> 1.0"

  backend "azurerm" {
  storage_account_name = "tstate6075"
  container_name = "tstate"
  key = "terraform.tfstate"
  access_key = "=="
******************************** // features {}
}
required_providers {
    azuread = "~> 1.0"  
    azurerm = "~> 2.0"
  }
  }

provider "azurerm" {
  tenant_id       = "*******************"
  //client_id       = var.client_id
  //client_secret   = var.client_secret
  subscription_id = "**********************"
  features {}
}

data "azurerm_resource_group" "az-rg-wu" {
  name = "rg-*****"
}

data "azurerm_client_config" "current" {}