Run modes and options

HCP Terraform runs support many of the same modes and options available in the Terraform CLI.

Plan and Apply (Standard)

The default run mode of HCP Terraform is to perform a plan and then apply it. If you have enabled auto-apply, a successful plan applies immediately. Otherwise, the run waits for user confirmation before applying.

• CLI: Use terraform apply (without providing a saved plan file).
• API: Create a run without specifying any options that select a different mode.
• UI: From the workspace's overview page, click + New run, and then choose Plan and apply (standard) as the run type.
• VCS: When a workspace is connected to a VCS repository, HCP Terraform automatically starts a standard plan and apply when you add new commits to the selected branch of that repository.

Destroy Mode

Destroy mode instructs Terraform to create a plan which destroys all objects, regardless of configuration changes.

• CLI: Use terraform plan -destroy or terraform destroy
• API: Use the is-destroy option.
• UI: Use a workspace's Destruction and Deletion settings page.

Plan Only/Speculative Plan

This option creates a speculative plan. The speculative plan shows a set of possible changes and checks them against Sentinel policies, but Terraform can not apply this plan.

You can create speculative plans with a different Terraform version than the one currently selected for a workspace. This lets you check whether your configuration is compatible with a newer Terraform version without changing the workspace settings.

Plan-only runs ignore the per-workspace run queue. Plan-only runs can proceed even if another run is in progress, can not become the workspace's current run, and do not block progress on a workspace's other runs.

• API: Set the plan-only option to true and specify an available terraform version using the terraform-version field.
• UI: From the workspace's overview page, click + New run, and then choose Plan only as the run type.
• VCS: When a workspace is connected to a VCS repository, HCP Terraform automatically starts a speculative plan when someone opens a pull request (or merge request) against the selected branch of that repository. The pull/merge request view in your VCS links to the speculative plan, and you can also find it in the workspace's run list.

Saved Plans

Saved plan runs are very similar to standard plan and apply runs: they perform a plan and then optionally apply it. There are three main differences:

1. No wait for planning. Saved plan runs ignore the per-workspace run queue during their plan and checks. Like plan-only runs, saved plans can begin planning even if another run is in progress, without blocking progress on other runs.
2. No auto-apply. Saved plan runs are never auto-applied, even if you enabled auto-apply for the workspace. Saved plans only apply if you confirm them.
3. Automatic discard for stale plans. If another run is applied (or the state is otherwise modified) before a saved plan run is confirmed, HCP Terraform automatically discards that saved plan. HCP Terraform may also automatically discard saved plans if they are not confirmed within a few weeks.

Saved plans are ideal for interactive CLI workflows, where you can perform many exploratory plans and then choose one to apply, or for custom continuous integration workflows where the default run queue behavior isn't suitable.

• CLI: Use terraform plan -out <FILE> to perform and save a plan, then use terraform apply <FILE> to apply the saved plan. Use terraform show <FILE> to inspect a saved plan before applying it.
• API: Use the save-plan option when creating a run. If you create a new configuration version for a saved plan run, use the provisional option so that it will not become the workspace's current configuration version until you decide to apply the run.

Allow Empty Apply

A no-operation (empty) apply enables HCP Terraform to apply a run from a plan that contains no infrastructure changes. During apply, Terraform can upgrade the state version if required. You can use this option to upgrade the state in your HCP Terraform workspace to a new Terraform version. Only some Terraform versions require this, most notably 0.13.

To make such upgrades easier, empty apply runs will always auto-apply if their plan contains no changes.

• API: Set the allow-empty-apply field to true.
• UI: From the workspace's overview page, click + New run, and then choose Allow empty apply as the run type.

Refresh-Only Mode

Hands-on: Try the Use Refresh-Only Mode to Sync Terraform State tutorial.

Refresh-only mode instructs Terraform to create a plan that updates the Terraform state to match changes made to remote objects outside of Terraform. This is useful if state drift has occurred and you want to reconcile your state file to match the drifted remote objects. Applying a refresh-only run does not result in further changes to remote objects.

• CLI: Use terraform plan -refresh-only or terraform apply -refresh-only.
• API: Use the refresh-only option.
• UI: From the workspace's overview page, click + New run, and then choose Refresh state as the run type.

Skipping Automatic State Refresh

The -refresh=false option is used in normal planning mode to skip the default behavior of refreshing Terraform state before checking for configuration changes.

• CLI: Use terraform plan -refresh=false or terraform apply -refresh=false.
• API: Use the refresh option.

Replacing Selected Resources

The replace option instructs Terraform to replace the object with the given resource address.

• CLI: Use terraform plan -replace=ADDRESS or terraform apply -replace=ADDRESS.
• API: Use the replace-addrs option.
• UI: Click + New run and select the Plan and apply (standard) run type. Then click Additional planning options to reveal the Replace resources option. Type the address of the resource that you want to replace. You can replace multiple resources.

Targeted Plan and Apply

Resource Targeting is intended for exceptional circumstances only and should not be used routinely.

• CLI: Use terraform plan -target=ADDRESS or terraform apply -target=ADDRESS.
• API: Use the target-addrs option.

The usual caveats for targeting in local operations imply some additional limitations on HCP Terraform features for remote plans created with targeting:

• Sentinel policy checks for targeted plans will see only the selected subset of resource instances planned for changes in the tfplan import and the tfplan/v2 import, which may cause an unintended failure for any policy that requires a planned change to a particular resource instance selected by its address.

• Cost Estimation is disabled for any run created with -target set, to prevent producing a misleading underestimate of cost due to resource instances being excluded from the plan.

You can disable or constrain use of targeting in a particular workspace using a Sentinel policy based on the tfrun.target_addrs value.

Generating Configuration

When using import blocks to import existing resources, Terraform can automatically generate configuration during the plan for any imported resources that don't have an existing resource block. This option is enabled by default for runs started from the UI or from a VCS webhook.

• CLI: Use terraform plan -generate-config-out=generated.tf.
• API: Use the allow-config-generation option.

You can find generated configuration displayed in the plan UI. If you're using the CLI workflow, Terraform will write generated configuration to the file you specify when running terraform plan.

Once Terraform has generated configuration for you, you'll need to review it, incorporate it in your Terraform configuration (including committing it to version control), then run another plan. If you try to directly apply a plan with generated configuration, the run will error.