OpenTofu: Installation, Workflow, and Building Blocks
Installing OpenTofu 🔗
OpenTofu is very easy to install and works on various Linux, Windows, and MacOS distributions. The installation method differs depending on your choice of operating system. The easiest is to use the installer script made available in the official documentation.
- Download the Installer script:
curl -fsSL https://get.opentofu.org/install-opentofu.sh -o install-opentofu.sh
- Grant execute permissions and review the script:
chmod +x install-opentofu.sh && less install-opentofu.sh
- Install using the script:
./install-opentofu.sh --install-method standalone
How Does OpenTofu Work? 🔗
OpenTofu leverages application programming interfaces (APIs) to create and manage resources on cloud platforms and other services. Through providers, OpenTofu can interact with virtually any platform or service that has an accessible API.
The OpenTofu community has already developed thousands of providers for various resources and services. All publicly available providers, including those for Amazon Web Services (AWS), Azure, Google Cloud Platform (GCP), Kubernetes, Helm, GitHub, and many others, are listed on the Public OpenTofu Registry.
OpenTofu Workflow 🔗
The core OpenTofu workflow consists of three steps.
Write: You define resources that may span multiple cloud providers and services. For example, you might create a configuration to deploy an application on virtual machines within a Virtual Private Cloud (VPC) network, complete with security groups and a load balancer.
Plan: During the planning phase, OpenTofu generates a detailed execution plan outlining its specific infrastructure actions. This plan describes precisely which resources will be created, updated, or destroyed by comparing the current state of your infrastructure with the desired state defined in your configuration files. By providing this execution plan, OpenTofu allows you to review and understand all proposed changes before they are implemented, ensuring that the modifications align with your expectations and reducing the risk of unintended consequences.
Apply: Once you approve the execution plan, OpenTofu implements the proposed changes by performing the necessary operations in the correct sequence. It respects all resource dependencies to maintain the integrity of your infrastructure. This means that resources are created, updated, or destroyed in an order that ensures each resource is ready when another depends on it.
Additionally, OpenTofu’s application process includes monitoring and handling any issues that arise during the execution. If an operation fails, it can stop the process to prevent cascading failures, allowing you to address the problem before proceeding. This careful management of resource dependencies and execution order helps maintain system stability and reliability throughout the infrastructure lifecycle.
For more details on the OpenTofu workflow, check out the documentation.
Basic Building Blocks: the CLI and the OpenTofu Language 🔗
The tofu CLI
🔗
tofu is the official command-line interface (CLI) tool designed to interact with OpenTofu. tofu allows users to define, provision, and manage cloud infrastructure resources in a consistent and automated manner. By leveraging tofu, developers and operations teams can efficiently manage complex infrastructure setups across multiple cloud providers and services.
| Command | Description |
|---|---|
| tofu init | Initialize the working directory with configuration files |
| tofu plan | Generate and display an execution plan for changes |
| tofu apply | Apply the changes required to reach the desired state |
| tofu destroy | Destroy all resources managed by the configuration |
| tofu fmt | Format configuration files for consistency |
| tofu validate | Validate the syntax and integrity of configuration files |
| tofu state list | List all resources in the current state |
| tofu state show | Show detailed information about a specific resource |
| tofu workspace new | Create a new workspace for managing separate environments |
| tofu workspace select | Switch to a different workspace |
| tofu import | Import an existing resource into Tofu’s state management |
The OpenTofu Language 🔗
The OpenTofu language is the primary way you interact with OpenTofu. You use it to write configuration files that tell OpenTofu what to do, such as installing plugins, creating infrastructure resources like servers or networks, and collecting essential data. This language also lets you define how resources depend on each other, so OpenTofu knows which tasks must happen first. It allows you to create multiple similar resources from a single block of code.
The main purpose of the OpenTofu language is to help you define the resources that make up your infrastructure, like virtual machines or storage. Other features of the language are there to make this process easier and more flexible. Instead of manually setting up everything, you write code to describe what you need. OpenTofu takes care of the rest, using your configuration as a guide to build and manage your resources, much like following a detailed instruction manual.
The syntax of the OpenTofu language consists of a few basic elements:
<BLOCK TYPE> "<BLOCK LABEL>" "<BLOCK LABEL>" {
# Block body
<IDENTIFIER> = <EXPRESSION> # Argument
}
- Blocks are used to group related settings and usually represent an object, like a resource. Each block has a specific type, can include labels for identification, and contains a body with arguments and other nested blocks. Most of the key features in OpenTofu are controlled through these top-level blocks in configuration files.
- Arguments are used inside blocks to assign specific values to names, defining settings for a resource or feature.
- Expressions represent values, either directly or by referencing or combining other values. These expressions are used as values for arguments or within other expressions.
The OpenTofu language is declarative, meaning you describe the desired outcome rather than listing the steps to achieve it. The order of blocks and how they’re arranged in files doesn’t matter much. OpenTofu focuses on the relationships between resources—whether defined directly or inferred—to determine the order of operations.
Migrating from Terraform 🔗
Migrating from Terraform to OpenTofu is a straightforward process, as OpenTofu is designed to maintain compatibility with existing Terraform configurations. Most Terraform .tf files can be used with OpenTofu without requiring significant changes, allowing organizations to transition seamlessly. The migration typically involves updating references to the OpenTofu binary and ensuring that any required providers are configured to work with OpenTofu. Additionally, OpenTofu provides documentation and tools to support the migration process, ensuring minimal disruption to existing infrastructure workflows. By migrating, organizations can benefit from OpenTofu’s open source community-driven development, avoiding vendor lock-in while maintaining the same powerful capabilities and workflows they’re accustomed to with Terraform.