What is Terraform Apply?

Terraform Apply is a command in the Terraform tool that applies the changes specified in a Terraform configuration to an infrastructure. After running the terraform plan command and reviewing the proposed changes, terraform apply executes those changes to create, modify, or delete resources as necessary, bringing the infrastructure into the desired state defined in the Terraform configuration files.

How Does Terraform Apply Work?

When you run the terraform apply command, Terraform uses the information from the configuration files (and any state files) to apply the changes to your infrastructure. It reads the plan created by terraform plan and proceeds with making the specified updates, including adding new resources, updating existing ones, or destroying outdated resources. Terraform Apply can be run with or without an explicit plan file, in which case it generates the plan before applying the changes. Key components of Terraform Apply include:

• Execution Plan: Terraform generates an execution plan that details the changes it will make based on the Terraform configuration and the current state.
• Resource Creation/Modification: Terraform creates, updates, or deletes resources based on the defined configuration, bringing the infrastructure to the desired state.
• Confirmation Prompt: When running terraform apply without a predefined plan, Terraform prompts the user to confirm the proposed changes before proceeding with their application.
• State Update: After applying changes, Terraform updates the state file to reflect the current configuration of the infrastructure.

Why Use Terraform Apply?

Terraform Apply is used to implement the infrastructure changes defined in Terraform configuration files. It allows for automated provisioning, updates, and teardown of resources, ensuring that the infrastructure is consistent with the specified configuration. The command also provides an easy way to manage complex infrastructures with minimal manual intervention, ensuring that infrastructure updates are applied safely and reliably.

Key Features of Terraform Apply

• Infrastructure Changes: Terraform Apply executes changes to your infrastructure, based on the configuration and planned actions defined by Terraform.
• Real-time Updates: It applies the changes in real-time, adjusting resources as needed to match the desired state.
• Safety Mechanism: The command provides a confirmation prompt to prevent accidental changes to the infrastructure and gives an opportunity for review before proceeding with updates.
• State Management: Terraform automatically updates the state file after applying changes, ensuring that the infrastructure state remains accurate and up to date.

Benefits of Terraform Apply

• Automation: Terraform Apply automates the process of infrastructure provisioning, modification, and deletion, reducing manual effort and increasing productivity.
• Consistency: Ensures that infrastructure changes are applied in a consistent, repeatable way across environments.
• Reduced Errors: By using Terraform to apply changes, errors caused by manual configurations or inconsistent environments are minimized.
• Version Control: Enables the management of infrastructure changes through version-controlled configuration files, ensuring infrastructure is managed in the same way as application code.

Use Cases for Terraform Apply

1. Infrastructure Deployment: Automates the creation of cloud infrastructure, including virtual machines, storage, and networking resources.
2. Environment Updates: Updates infrastructure to match changes made in configuration files, such as scaling resources or modifying configurations.
3. Resource Cleanup: Deletes or reconfigures outdated or unused resources to optimize infrastructure and reduce costs.
4. Multi-Environment Management: Applies consistent infrastructure changes across multiple environments (e.g., development, staging, production) using the same Terraform configuration.

Summary

Terraform Apply is a critical command in the Terraform workflow that applies the desired changes to your infrastructure. It automates the provisioning, modification, and teardown of resources based on the configuration, ensuring infrastructure consistency, reducing errors, and enabling efficient management of cloud environments.