Change infrastructure

Now that you have provisioned infrastructure with HCP Terraform, you are ready to make changes to that infrastructure.

HCP Terraform offers multiple ways to set variable values for your configuration. In the previous tutorial, you defined your variables in the web UI. Now, you will use per-run variables passed on the command line to modify your EC2 instance configuration.

Explore your workspace

The landing page for a workspace includes an overview of its current state and configuration.

The top of the workspace overview page reports the following information:

• the lock icon to indicate if the workspace is locked, which prevents others from triggering new runs.
• the resource count for the workspace.
• the Terraform version used for the workspace.
• the time since the last update.
• the Lock button that lets you lock and unlock the workspace.
• the New run button, which allows you to trigger a new run.

The rest of the page shows details about the most recent run and current settings for your workspace.

• The Latest run section displays details of the last run, including a count of resource modifications, duration, and estimated change in cost.
• The resources and outputs tables display details about the current infrastructure and any outputs defined for the workspace.
• The sidebar contains metrics and details about workspace settings. It also includes a section for workspace tags. You can manage your workspace's tags here, and your list of tags in your Organization settings. Tags allow you to group and filter your workspaces.

The workspace's menu lists available actions and configurations for the workspace.

• The Runs page lists all of the plan and apply actions you have taken with this workspace.
• The States page lists the state files for all successful past runs in the workspace. Terraform records data about your resources as a tfstate file. The state file is central to Terraform operations, and Terraform uses it to determine which changes to make to your resources over their lifecycle.
• The Variables page lists the Terraform variables, environment variables, and variable sets configured for the workspace.
• The Settings page contains all of the HCP Terraform settings for your workspace, and is where you will destroy your infrastructure at the end of these tutorials.

Navigate to the the Runs page, and notice the run attributes that you can filter the list of runs by.

• Status lets you filter by the stage of the run, such as Applied, Discarded, or Pending.
• Operation lets you filter by the run type, such as Refresh only, Apply, or Destroy.
• Source lets you filter by the run workflow, UI, VCS, or API.

Edit variables

Use variables to make your configuration flexible enough to use in different contexts. Setting variable values is one of the most common ways to customize Terraform configuration, and HCP Terraform supports multiple ways to manage variables.

Like Terraform Community Edition, you can pass per-run variables to HCP Terraform using command line flags. When using the CLI-driven workflow for HCP Terraform, any variables passed using the -var flag will override workspace-specific variables. However, HCP Terraform will not save the new value in your workspace unless you update the variable in the UI. This feature can be useful when you want to test or temporarily apply a change that you expect to revert on the next apply, so your stored variable values continue to reflect the desired eventual configuration.

In your terminal, start a new Terraform run for your workspace. Use a command line variable to update the instance type for your EC2 instance to t2.small.

$ terraform apply -var="instance_type=t2.small"
Running apply in HCP Terraform. Output will stream here. Pressing Ctrl-C
will cancel the remote apply if it's still pending. If the apply started it
will stop streaming the logs, but will not stop the apply running remotely.

Preparing the remote apply...

To view this run in a browser, visit:
https://app.terraform.io/app/hashicorp-training/learn-terraform/runs/run-zRZTVvu....
##...

Once again, Terraform will trigger a run in your learn-terraform workspace and stream the output to your terminal. You can also review the details for the run in the workspace itself.

The Terraform AWS provider determined that it can modify your instance type in place. Approve the run to resize your EC2 instance.

Next Steps

Review the documentation on variables in HCP Terraform to learn more about variable precedence in a workspace.

In these tutorials, you created an HCP Terraform account and organization, authenticated from the command line, created an HCP Terraform workspace, and used the CLI-driven workflow to create and modify infrastructure.

In the next tutorial, you will update your workspace settings to instead use the VCS-driven workflow and trigger Terraform operations off of pull requests.