Terraform.workspace interpolation - Step-by-Step Execution

Process Flow - Terraform.workspace interpolation

Start Terraform run

↓

Detect current workspace

↓

Interpolate ${terraform.workspace}

↓

Use workspace name in config

↓

Apply config with workspace-specific values

↓

End

Terraform detects the current workspace, replaces ${terraform.workspace} with its name, and applies configuration accordingly.

Execution Sample

Terraform

resource "aws_s3_bucket" "example" {
  bucket = "myapp-${terraform.workspace}-bucket"
  acl    = "private"
}

Creates an S3 bucket with a name that includes the current Terraform workspace.

Process Table

Step	Action	terraform.workspace Value	Resulting Bucket Name
1	Start Terraform apply in workspace 'default'	default	myapp-default-bucket
2	Apply configuration with interpolated bucket name	default	myapp-default-bucket
3	Switch workspace to 'dev'	dev	myapp-dev-bucket
4	Apply configuration with interpolated bucket name	dev	myapp-dev-bucket
5	Switch workspace to 'prod'	prod	myapp-prod-bucket
6	Apply configuration with interpolated bucket name	prod	myapp-prod-bucket
7	End - workspace interpolation done for each workspace

💡 Terraform finishes applying configuration using the current workspace name for interpolation.

Status Tracker

Variable	Start	After Step 3	After Step 5	Final
terraform.workspace	default	dev	prod	prod
bucket name	myapp-default-bucket	myapp-dev-bucket	myapp-prod-bucket	myapp-prod-bucket

Key Moments - 2 Insights

Why does the bucket name change when switching workspaces?

Because ${terraform.workspace} is replaced with the current workspace name at each apply step, as shown in execution_table rows 1, 3, and 5.

Is the bucket name fixed or dynamic?

It is dynamic and depends on the workspace, demonstrated by the variable_tracker showing bucket name changes after workspace switches.

Visual Quiz - 3 Questions

Look at the execution_table, what is the bucket name at Step 4?

A myapp-default-bucket

B myapp-prod-bucket

C myapp-dev-bucket

D myapp-test-bucket

💡 Hint

Check the terraform.workspace value and bucket name at Step 4 in the execution_table.

At which step does terraform.workspace first change from 'default'?

A Step 2

B Step 3

C Step 5

D Step 6

💡 Hint

Look at the terraform.workspace column in the execution_table to find when it changes from 'default'.

If you add a new workspace 'test', what would the bucket name be when applying in that workspace?

A myapp-test-bucket

B myapp-prod-bucket

C myapp-default-bucket

D myapp-dev-bucket

💡 Hint

Refer to how bucket names are formed by combining 'myapp-' with the current workspace name from variable_tracker.

Concept Snapshot

Terraform.workspace interpolation:
- Use ${terraform.workspace} to get current workspace name.
- Workspace name changes with 'terraform workspace select'.
- Interpolation updates config dynamically per workspace.
- Useful for naming resources uniquely per environment.
- Always run 'terraform workspace select' before apply.

Full Transcript

Terraform uses the special variable terraform.workspace to know which workspace is active. When you write ${terraform.workspace} in your configuration, Terraform replaces it with the current workspace name during apply. This lets you create resources with names that change depending on the workspace, like different buckets for dev, prod, or default. The execution table shows how the bucket name changes as you switch workspaces and apply the config. The variable tracker confirms terraform.workspace and bucket name values update step by step. This helps keep environments separate and organized.