Overview
Terraform implements an Infrastructure as Code (IaC) approach to manage infrastructure with code, reducing manual configuration errors and ensuring consistency and repeatability in infrastructure deployments. It supports various cloud providers (AWS, Azure, GCP, etc.) and on-premises solutions, offering powerful features to plan and review infrastructure changes beforehand.
Key Features
- Infrastructure as Code (IaC): Define infrastructure as code using HCL (HashiCorp Configuration Language).
- Multi-Cloud Support: Supports various cloud and service providers like AWS, Azure, GCP, and more.
- State Management: Tracks the actual state of your infrastructure to efficiently manage changes.
- Execution Plan Preview: Allows you to preview which resources will be created, modified, or deleted before applying changes.
Key Commands (Subcommands)
Terraform performs infrastructure management workflows through various subcommands.
Core Workflow
Utilities
Generated command:
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Description:
`terraform` Executes the command.
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Usage Examples
Examples demonstrating the typical workflow of Terraform.
Initialize Terraform Project
terraform initRun this after starting a new Terraform project or cloning an existing one to download necessary providers.
Preview Infrastructure Change Plan
terraform planSee how the changes defined in your configuration files will be applied to your actual infrastructure. No actual resource changes occur at this stage.
Deploy or Update Infrastructure
terraform apply --auto-approveApplies the changes reviewed with the 'plan' command to your actual cloud or on-premises infrastructure. The `--auto-approve` option skips the confirmation prompt.
Destroy Infrastructure Resources
terraform destroy --auto-approveDestroys all resources managed by Terraform. Use this command with extreme caution.
Format Configuration Files
terraform fmtAutomatically formats all Terraform configuration files (.tf) in the current directory to a standard style.
Installation
Terraform is not typically included by default in most Linux distributions. You need to download the binary from the official HashiCorp website. Here's the recommended installation method for Debian/Ubuntu-based systems.
Install via APT Repository (Debian/Ubuntu)
sudo apt-get update && sudo apt-get install -y gnupg software-properties-common curl
curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo apt-key add -
sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"
sudo apt-get update && sudo apt-get install terraformThis method involves adding HashiCorp's official APT repository and then installing Terraform. It's convenient for keeping Terraform up-to-date.
Verify Installation
After installation, run the following command to confirm that Terraform has been installed correctly.
Check Version
terraform -vTips & Best Practices
Tips and best practices for effectively using Terraform and preventing potential issues.
Key Tips
- State File Management: The `terraform.tfstate` file records the current state of your infrastructure. It's crucial to manage it securely and avoid committing it directly to version control systems. Using remote backends like S3, Azure Blob Storage, or GCS is common practice.
- Use Modules: Create and manage reusable infrastructure components as modules to improve code readability and maintainability.
- Review Plans: Always review changes with `terraform plan` before applying them to prevent unintended resource modifications or deletions, especially in production environments.
- Version Control: Always manage Terraform configuration files (.tf) with a version control system like Git to track changes and facilitate collaboration.
- Sensitive Data Management: Avoid hardcoding sensitive information like API keys and passwords directly in configuration files. Use environment variables, Terraform variables (tfvars), or secret management tools like Vault.
Precautions
- The `terraform destroy` command is irreversible. Always double-check before execution and perform backups if necessary.
- State File Corruption: Corrupted state files can lead to Terraform misinterpreting the actual infrastructure state, causing problems. Reduce this risk by using remote backends and state locking.
- Version Mismatches: Inconsistencies between Terraform CLI versions and provider versions can lead to unexpected behavior. It's recommended to pin provider versions using the `.terraform.lock.hcl` file.