Variables and outputs in GCP - Step-by-Step Execution

Process Flow - Variables and outputs

Define Variables

↓

Use Variables in Config

↓

Deploy Infrastructure

↓

Capture Outputs

↓

View Outputs

↓

Use Outputs Elsewhere

This flow shows how variables are defined, used in deployment, and how outputs are captured and viewed after deployment.

Execution Sample

GCP

variable "region" {
  default = "us-central1"
}

output "instance_zone" {
  value = "${var.region}-a"
}

Defines a variable for region and outputs a computed instance zone based on that variable.

Process Table

Step	Action	Variable State	Output Value	Notes
1	Define variable 'region' with default 'us-central1'	region = 'us-central1'		Variable ready for use
2	Use variable 'region' to compute output 'instance_zone'	region = 'us-central1'	instance_zone = 'us-central1-a'	Output expression evaluated
3	Deploy infrastructure using variable 'region'	region = 'us-central1'		Deployment uses variable value
4	Capture output 'instance_zone' after deployment	region = 'us-central1'	instance_zone = 'us-central1-a'	Output available for viewing
5	View output 'instance_zone'	region = 'us-central1'	instance_zone = 'us-central1-a'	Output shown to user
6	Use output 'instance_zone' in another config or script	region = 'us-central1'	instance_zone = 'us-central1-a'	Output passed as input elsewhere
7	End of process	region = 'us-central1'	instance_zone = 'us-central1-a'	All steps complete

💡 All variables defined and outputs captured successfully after deployment

Status Tracker

Variable	Start	After Step 1	After Step 2	Final
region	undefined	us-central1	us-central1	us-central1
instance_zone	undefined	undefined	us-central1-a	us-central1-a

Key Moments - 2 Insights

Why does the output 'instance_zone' depend on the variable 'region'?

Because in the execution_table at Step 2, the output value is computed using the variable 'region', showing the dependency clearly.

Can outputs be used before deployment?

No, outputs are only available after deployment as shown in Step 4 and Step 5 where the output is captured and viewed after infrastructure is deployed.

Visual Quiz - 3 Questions

Look at the execution_table at Step 2, what is the value of 'instance_zone'?

A us-central1-a

B us-central1

C undefined

D a-us-central1

💡 Hint

Check the 'Output Value' column at Step 2 in the execution_table

At which step does the deployment use the variable 'region'?

A Step 1

B Step 3

C Step 5

D Step 6

💡 Hint

Look at the 'Action' column for deployment usage in the execution_table

If the variable 'region' changed to 'europe-west1', what would be the new output 'instance_zone'?

A europe-west1

B us-central1-a

C europe-west1-a

D a-europe-west1

💡 Hint

Refer to how 'instance_zone' is computed from 'region' in the execution_sample and execution_table

Concept Snapshot

Variables store input values for deployment.
Outputs show results after deployment.
Define variables with defaults or inputs.
Use variables in resource configs.
Outputs can be used elsewhere after deployment.

Full Transcript

This lesson shows how variables and outputs work in cloud infrastructure deployment. First, variables are defined with default values or user inputs. Then, these variables are used in the configuration to customize resources. When the infrastructure is deployed, outputs are computed based on variables or resource attributes. Outputs become available after deployment and can be viewed or used in other configurations. The execution table traces each step from defining variables, using them, deploying, capturing outputs, and using outputs elsewhere. Variables hold values throughout, and outputs depend on those variables. This helps make deployments flexible and reusable.