Terraform Output

Terraform configurations often produce valuable data, like IP addresses, resource IDs, or other details generated during deployment. The terraform output command allows you to extract and display this information in a readable format, making it easier to share or integrate into other workflows.

Why Use terraform output?

  • To retrieve and display outputs defined in your Terraform configuration.
  • To integrate output values into scripts or external systems.
  • To validate that resources have been created or updated successfully.

How to Use It?

  • To view all outputs: Run terraform output. This lists all outputs defined in your configuration.
  • To view a specific output: Use terraform output <output_name>, replacing <output_name> with the name of the output you want to retrieve.
  • To view outputs from a specific state file: Use the -state flag, e.g., terraform output -state=example.tfstate.
  • To display outputs in JSON format: Use the -json flag, e.g., terraform output -json.

Example: Using Terraform Output

Suppose your configuration includes an output block for an EC2 instance's public IP address:

output "instance_ip" {
  value = aws_instance.example.public_ip
}

After deploying the infrastructure, you can retrieve the public IP with:

terraform output instance_ip

Output:

54.123.45.67

To list all outputs, run:

terraform output

Output:

instance_ip = 54.123.45.67
instance_id = i-0abcd1234efgh5678

If you need the output in JSON format for integration with other tools, run:

terraform output -json

Output:

{
  "instance_ip": {
    "value": "54.123.45.67",
    "type": "string"
  },
  "instance_id": {
    "value": "i-0abcd1234efgh5678",
    "type": "string"
  }
}

Use Case

Imagine you’re setting up a pipeline that needs the public IP of an EC2 instance to configure DNS records. By defining and retrieving the output with terraform output, you can pass this information directly into your automation scripts, simplifying the process.

Conclusion

The terraform output command bridges the gap between infrastructure deployment and integration. By making essential resource information accessible, it ensures your workflows remain efficient and interconnected.

Glossary