Azure DevOps Pipeline to Deploy Terraform fails

Question

I've got this ADO pipeline to run Terraform Plan then Deploy it

The job does the plan correctly, then stop for an approval, then when try to Init again and the deployment stage i'm getting this error below.

When I try to add a task to install Terraform again it doesn't work either.

Any idea what's wrong with my build pipeline please?

Error:

Starting: Terraform Init
==============================================================================
Task         : Terraform
Description  : Execute terraform commands to manage resources on AzureRM, Amazon Web Services(AWS) and Google Cloud Platform(GCP). v4.241.11
Version      : 4.241.33
Author       : Microsoft Corporation
Help         : [Learn more about this task](https://aka.ms/devlabs/ado/tf/task/v4)
==============================================================================
##[error]Error: **Failed to find terraform tool in paths
Finishing: Terraform Init**

Pipeline:

pr: none
trigger: none

stages:
- stage:
  displayName: Terraform Plan
  jobs:
  - job: TerraformPlan 
    displayName: Terraform Plan
    condition: succeeded()
    pool: azc-vmss-man-ado-uks-001
    steps:
    - task: TerraformInstaller@1
      inputs:
        terraformVersion: 'latest'
    - task: TerraformTaskV4@4
      displayName: Terraform Init 
      inputs:
        provider: 'azurerm'
        command: 'init'
        workingDirectory: '$(System.DefaultWorkingDirectory)/projects/skeleton'
        backendAzureRmUseEnvironmentVariablesForAuthentication: false
        backendAzureRmUseEntraIdForAuthentication: false
        backendServiceArm: 'azure-dev'
        backendAzureRmResourceGroupName: 'azc-rg-dev-devops-uks-001'
        backendAzureRmStorageAccountName: 'azcstordevterfrmuks001'
        backendAzureRmContainerName: 'terraform'
        backendAzureRmKey: 'skeleton'
    - task: TerraformTaskV4@4
      displayName: Terraform Plan
      inputs:
          provider: 'azurerm'
          command: 'plan'
          workingDirectory: '$(System.DefaultWorkingDirectory)/projects/skeleton'
          commandOptions: '-var-file=./tfvars/dev.tfvars -out=deployment.tfplan -input=false -out=deployment.tfplan'
          environmentServiceNameAzureRM: 'azure-dev'
- stage:
  displayName: Terraform Apply
  jobs:
    - deployment: Apply
      pool: azc-vmss-man-ado-uks-001
      environment: azure-spoke-dev-app-skeleton
      displayName: Terraform Apply
      condition: succeeded()
      strategy:
        runOnce:
          deploy:
            steps:
              - task: TerraformTaskV4@4
                displayName: Terraform Init 
                inputs:
                  provider: 'azurerm'
                  command: 'init'
                  workingDirectory: '$(System.DefaultWorkingDirectory)/projects/skeleton'
                  backendAzureRmUseEnvironmentVariablesForAuthentication: false
                  backendAzureRmUseEntraIdForAuthentication: false
                  backendServiceArm: 'azure-dev'
                  backendAzureRmResourceGroupName: 'azc-rg-dev-devops-uks-001'
                  backendAzureRmStorageAccountName: 'azcstordevterfrmuks001'
                  backendAzureRmContainerName: 'terraform'
                  backendAzureRmKey: 'skeleton'

              - task: TerraformTaskV4@4
                displayName: Terraform Plan
                inputs:
                  provider: 'azurerm'
                  command: 'plan'
                  workingDirectory: '$(System.DefaultWorkingDirectory)/projects/skeleton'
                  commandOptions: '-var-file=./tfvars/dev.tfvars -out=deployment.tfplan -input=false -out=deployment.tfplan'
                  environmentServiceNameAzureRM: 'azure-dev'
                                  
              - task: TerraformTaskV4@4
                inputs:
                  provider: 'azurerm'
                  command: 'apply'
                  workingDirectory: '$(System.DefaultWorkingDirectory)/projects/skeleton'
                  commandOptions: '-input=false deployment.tfplan'
                  environmentServiceNameAzureRM: 'azure-dev'
          

Answer 1

Based on your description, it appeared that your pipeline was running on VMSS self-hosted agents. If you have configured more than one instance for your VMSS resource, the two agent jobs in this pipeline may have been running on different agent machines.

Even if both jobs run on the same VMSS instance, you still need to add the TerraformInstaller@1 task for each agent job. This task simply downloads Terraform into $(Agent.ToolsDirectory) for use in subsequent steps within the same job — it does not install Terraform globally on the agent machine. The only exception is if your VMSS instances were scaled out using an image that already included the Terraform toolset.

Additionally, unlike a traditional job, where the first default step is - checkout: self, a deployment job starts with - download: current by default to download artifacts published in the current run. Since no pipeline artifacts were published before the deployment: Apply job, if it ran on a different agent machine than the job: TerraformPlan, it had no access to the Terraform templates needed for initialization, planning, or applying changes.

To help you troubleshoot and resolve this issue, I suggest adding the following three steps to your deployment: Apply job. These steps ensure that Terraform is installed, the templates are checked out from your repository, and the necessary requirments are verified before running terraform init.

...
          steps:
          - checkout: self
          - task: TerraformInstaller@1
            inputs:
              terraformVersion: 'latest'
          - script: |
              terraform -version
              echo "Agent.Name - $(Agent.Name)"
              echo "Agent.MachineName - $(Agent.MachineName)"
              echo "System.DefaultWorkingDirectory - $(System.DefaultWorkingDirectory)"
              tree $(System.DefaultWorkingDirectory)
...