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Using the terraform cloud configuration block

Ned Bellavance
8 min read

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Terraform 1.1 brings with it some new cool Terraform Cloud management options. Cloud blocks, Tags, and Workspace commands Oh MY! But wait. What was broken about the old system? And why is this better? Let’s dig in.

Terraform Cloud Workspaces

Everything in here is about the CLI workflow for a Terraform Cloud workspace. If you’re using the VCS or API workflow, you can safely ignore most of this post. The only major improvement for you is the proper evaluation of terraform.workspace.

Terraform Remote Backend

Before Terraform 1.1, the way you connected a Terraform configuration to Terraform Cloud in a CLI workflow was through the use of the backend block in a terraform configuration block. The backend type was remote and it came with settings for the hostname, organization, and workspaces.

The workspace block had two possible arguments:

  • name: associated the configuration with a single workspace in TFC with a matching name.
  • prefix: matched your current local workspace to a workspace in TFC by adding a prefix.

The two arguments are mutually exclusive. You might be wondering about the prefix, so allow me to illustrate with an example:

terraform {
    backend "remote" {
        hostname = "app.terraform.io"
        organization = "taconet"
        workspaces {
            prefix = "networking-"
        }
    }
}

When you initialize the configuration, it will look for any workspaces in the target organization that have the prefix “networking-”. The next action will depend on what it finds:

  • No matching workspace: Terraform will prompt you to create one using the terraform workspace command.
  • One matching workspace: Terraform will automatically select the workspace for you.
  • Multiple matching workspaces: Terraform will prompt you to select a workspace from the list.

Since we are starting with an empty organization, there will be no matching workspaces. The following command will create a workspace:

terraform workspace new dev

Listing out the workspaces at the CLI will show the following:

$ terraform workspace list

* dev

Looking at the workspaces on Terraform Cloud, you’ll see a workspace called networking-dev. Terraform is adding the prefix for the workspace it generated in Terraform Cloud.

The main problem with the prefix argument is the cognitive dissonance between what you’re seeing at the command line - a workspace called dev, and in Terraform Cloud - a workspace called networking-dev. This is further compounded by a problem with the terraform.workspace value.

Before Terraform 1.1, the workspace used by the remote runner was always the default workspace. If you used the terraform.workspace value in your code, it would evaluate to default no matter what the name of the workspace was locally or in Terraform Cloud.

Terraform 1.1 set out to fix this and add room for future capabilities.

Terraform Cloud Block

Terraform 1.1 introduced the cloud block as an alternative to backend "remote". The arguments were mostly the same including hostname and organization. The main change was with the workspaces block, which now had the name and tags arguments.

  • name: associated the configuration with a single workspace in TFC with a matching name.
  • tags: match your current local workspaces to workspaces with matching tags.

One of the goals behind the cloud block was to remove the cognitive dissonance between local workspaces and Terraform Cloud workspaces.

How did it do that? By giving you full control over naming each workspace, but at the same time applying consistent metadata tags to each workspace associated with a configuration. An example would be helpful.

terraform {
    cloud {
        organization = "taconet"

        workspaces {
            tags = ["cloud:aws", "security"]
        }
    }
}

When you initialize the configuration, Terraform will look for any workspaces in the target organization that have the tags “cloud:aws” and “security”. The next action will depend on what it finds:

  • No matching workspace: Terraform will prompt you to create one directly.
  • One matching workspace: Terraform will automatically select the workspace for you.
  • Multiple matching workspaces: Terraform will prompt you to select a workspace from the list.

You might notice that instead of asking you to creating a workspace using the terraform workspace new command, the dialog prompts you to do so as part of the workflow. That’s a small, but appreciated improvement to the experience.

Let’s say I created a workspace called shared-services-dev during initialization. Running the terraform workspace list command would show me the following:

$ terraform workspace list

* shared-services-dev

Looking at the workspaces on Terraform Cloud, I will see a workspace named shared-services-dev with the tags “cloud:aws” and “security”. The dissonance between my local workspaces and what I see in Terraform Cloud is gone.

Even better, regardless of which workflow you use, Terraform 1.1 will use the actual workspace name on the remote runner. That means the terraform.workspace value will evaluate properly again.

Migrating from Backend Remote to Cloud

What if you’ve gone all in on using the backend "remote" method to manage your workspaces and now you want to move to the cloud block? Whether you are using the name or prefix argument in your backend block, the migration process is essentially the same.

If you’ve been using the prefix argument, then you will need to decide on tags to apply to the migrating workspace. For the name argument, you can simply use the same value for the name argument in the cloud block.

Let’s look at an example of the prefix scenario. We’ve got three workspaces in Terraform Cloud: application-dev, application-staging, and application-prod. The current backend block looks like this:

terraform {
    backend "remote" {
        hostname = "app.terraform.io"
        organization = "taconet"
        workspaces {
            prefix = "application-"
        }
    }
}

And a workspace listing on your local workstation would show the following:

$ terraform workspace list

  dev
* prod
  staging

The first thing to remember is that all the state data and workspace information is stored up in Terraform Cloud. The workspaces you have on your local workstation do not matter. What you’re trying to do is map to the Terraform Cloud workspaces using the new cloud block. Since we have multiple workspaces using the same configuration, we are going to use the tags argument.

Let’s say we want to use the tag “app:taco” to identify our migrated workspaces. We can update our configuration replacing the backend block with the cloud block:

terraform {
    cloud {
        organization = "taconet"

        workspaces {
            tags = ["app:taco"]
        }
    }
}

Because we are changing our backend, we need to run terraform init. You might think you need to go into Terraform Cloud and add the “app:taco” tag to the three workspaces, but you don’t! When you run terraform init, Terraform will recognize you are migrating from the remote backend to the cloud backend. Stored in the local state file is the following information:

"backend": {
        "type": "remote",
        "config": {
            "hostname": "app.terraform.io",
            "organization": "taconet",
            "token": null,
            "workspaces": {
                "name": null,
                "prefix": "application-"
            }
        },
        "hash": 1338747517
    }

During the migration process, Terraform will use the prefix information stored in local state and your existing list of local workspaces to find the matching workspaces in Terraform Cloud. Then it will apply the tags list in the cloud block and migrate the state. It will also update your local workspace names to match the names in Terraform Cloud.

One important caveat! If you have a bunch of existing workspaces in Terraform Cloud, chances are they are set to use an older version of Terraform. The cloud block and migration functionality require that your Terraform Cloud workspace is at Terraform v1.1 or higher. Before you run the migration, go into each impacted workspace and update the Terraform version in the General settings. If you don’t, you’ll get this fun message:

│ Error: Error migrating the workspace "dev" from the previous "remote" backend
│ to the newly configured "cloud" backend:
│     Error loading state:
│     Remote workspace Terraform version "1.0.1" does not match local Terraform version "1.1.2"

Don’t worry! Nothing is broken. Terraform fails gracefully on the migration. Simply go and update the workspaces to the proper Terraform version and run terraform init again.

Once the migration completes, you’ll see that your local workspace names now match what is in Terraform Cloud, and the Terraform Cloud workspaces have the proper tags.

Migration complete! Your workspaces are as follows:
* application-dev
  application-prod
  application-staging

Cloud Block Questions

HashiCorp could have introduced these improvements without creating a new configuration block type, so why did they do it? In part, I think it comes down to semantics. Terraform Cloud isn’t just a backend, it’s got a lot more services and features, including remote operations. Creating the cloud configuration block makes the difference clear and creates a migration path.

The other part is future updates and features. Instead of adding more arguments to the backend block that are Terraform Cloud specific, they can leave the backend block alone and introduce new options in the cloud block. What are those new options? No idea. But you can bet they’re coming soon.

Conclusion

The new cloud block in Terraform 1.1 provides an improved experience for those using the CLI workflow. Workspace names match between local and Terraform Cloud, and you can use tags to manage multiple workspaces. This change paves the way for future improvements in Terraform Cloud and the CLI experience. Migration from the remote backend is a simple affair as long as you remember to update the version of Terraform used by your workspaces.

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