Failed to load “tfplan” as a plan file

Question

I am performing a very simple testing on TF + AzureDevops pipeline. the plan stage is success but the Deploy stage is failing with Failed to load “tfplan” as a plan file

I can see a new plan file is generated in my azure blog storage container and I am using the same name in the plan and deploy stage job.

if I use terraform apply in the same job, then the job is success.

how do I ensure both the TerraformPlan and TerraformApply jobs using the same plan file?

Please help:

trigger:

main
pool:
vmImage: ‘ubuntu-latest’

variables:

group: KV-SQL-SERVER-TEST
stages:

stage: Plan
displayName: ‘Terraform Plan’
jobs:

job: TerraformPlan
displayName: ‘Terraform Plan’
steps:
task: TerraformInstaller@0
inputs:
terraformVersion: ‘latest’
script: |
terraform --version
terraform init -backend-config=“access_key=$(storagetest101-key1)”
terraform plan -out=tfplan
displayName: ‘Terraform Init and Plan’


stage: Deploy
displayName: ‘Terraform Apply’
jobs:

job: TerraformApply
displayName: ‘Terraform Apply’
steps:
task: TerraformInstaller@0
inputs:
terraformVersion: ‘latest’

script: |
terraform --version
terraform init -backend-config=“access_key=$(storagetest101-key1)”
terraform validate
terraform apply -auto-approve -input=false tfplan
displayName: ‘Terraform Init and Apply’

Answer 1

It's the expected behavior. You are running terraform plan and terraform apply in the different jobs. When you use MS-hosted agents, each job will get a brand-new agent. That's to say that your terraform plan and terraform apply are running on the different agents, so that terraform apply can't find the target plan file.

As a workaround, you can publish the plan file into a build artifact in job "TerraformPlan" and download the artifact in job "TerraformApply" to consume the plan file. I have modified your yaml file as shown below.

trigger:
- main
pool:
  vmImage: ‘ubuntu-latest’

variables:
  group: KV-SQL-SERVER-TEST
stages:
- stage: Plan
  displayName: ‘Terraform Plan’
  jobs:
  - job: TerraformPlan
    displayName: ‘Terraform Plan’
    steps:
    - task: TerraformInstaller@0
      inputs:
        terraformVersion: ‘latest’
    - script: |
        terraform --version
        terraform init -backend-config=“access_key=$(storagetest101-key1)”
        terraform plan -out=tfplan
      displayName: ‘Terraform Init and Plan’
    
    - task: CopyFiles@2
      inputs:
        SourceFolder: '$(System.DefaultWorkingDirectory)'
        Contents: '*tfplan*'
        TargetFolder: '$(Build.ArtifactStagingDirectory)'
    - task: PublishBuildArtifacts@1
      inputs:
        PathtoPublish: '$(Build.ArtifactStagingDirectory)'
        ArtifactName: 'planfile'
        publishLocation: 'Container'

- stage: Deploy
  displayName: ‘Terraform Apply’
  jobs:
  - job: TerraformApply
    displayName: ‘Terraform Apply’
    steps:
    - task: DownloadBuildArtifacts@1
      inputs:
        buildType: 'current'
        downloadType: 'single'
        artifactName: 'planfile'
        downloadPath: '$(System.DefaultWorkingDirectory)'
    - task: TerraformInstaller@0
      inputs:
        terraformVersion: ‘latest’

    - script: |
        terraform --version
        terraform init -backend-config=“access_key=$(storagetest101-key1)”
        terraform validate
        terraform apply -auto-approve -input=false planfile/tfplan
      displayName: ‘Terraform Init and Apply’