Task inputs

Input	Required	Description	Default
planPath	Yes	Path to a Terraform plan — binary (terraform plan -out=…) or JSON (terraform show -json). Binary plans are converted on the agent.	–
attachmentName	No	Identifier for the attachment; used as the label in the tab's plan selector.	terraform-plan
cliTool	No	CLI used to convert binary plans: auto, terraform, or tofu. Ignored for JSON plans.	auto

planPath

Point this at the plan file your pipeline produced. Both forms are accepted:

• Binary — terraform plan -out=tfplan (or tofu plan -out=tfplan). The task runs show -json on the agent to convert it, so the CLI must be available — see cliTool.
• JSON — terraform show -json tfplan > tfplan.json (or tofu show -json). Pre-converted, so the publishing agent doesn't need either CLI.

attachmentName

Only relevant when you publish more than one plan per build (see the multi-stage example). Each distinct attachmentName becomes an entry in the tab's dropdown; alphabetical order decides which is selected first. With a single plan the selector is hidden.

cliTool

Only used when planPath is a binary plan.

• auto (default) — uses terraform if it is on PATH, otherwise tofu.
• terraform / tofu — use that CLI only. Set tofu when both are installed but the plan was produced by OpenTofu.

The CLI is always looked up on the PATH of the account running the agent; cliTool doesn't accept a file path, and any other value fails the task. If the CLI is installed somewhere else, add its directory to PATH in an earlier step:

- script: echo "##vso[task.prependpath]/opt/tofu/bin"

- task: TerraformPlanViewer@1
  inputs:
    planPath: '$(System.DefaultWorkingDirectory)/tfplan'
    cliTool: 'tofu'