docs: updated documentation to OpenTofu in addition to Terraform

README.md

@@ -10,7 +10,7 @@
 
 <p align="center">
   <img src="./runatlantis.io/public/hero.png" alt="Atlantis Logo"/><br><br>
-  <b>Terraform Pull Request Automation</b>
+  <b>Terraform & OpenTofu Pull Request Automation</b>
 </p>
 
 - [Resources](#resources)
@@ -20,22 +20,27 @@
 - [Stargazers over time](#stargazers-over-time)
 
 ## Resources
-* How to get started: [www.runatlantis.io/guide](https://www.runatlantis.io/guide)
-* Full documentation: [www.runatlantis.io/docs](https://www.runatlantis.io/docs)
-* Download the latest release: [github.com/runatlantis/atlantis/releases/latest](https://github.com/runatlantis/atlantis/releases/latest)
-* Get help in our [Slack channel](https://slack.cncf.io/) in channel #atlantis and development in #atlantis-contributors
-* Start Contributing: [CONTRIBUTING.md](CONTRIBUTING.md)
+
+- How to get started: [www.runatlantis.io/guide](https://www.runatlantis.io/guide)
+- Full documentation: [www.runatlantis.io/docs](https://www.runatlantis.io/docs)
+- Download the latest release: [github.com/runatlantis/atlantis/releases/latest](https://github.com/runatlantis/atlantis/releases/latest)
+- Get help in our [Slack channel](https://slack.cncf.io/) in channel #atlantis and development in #atlantis-contributors
+- Start Contributing: [CONTRIBUTING.md](CONTRIBUTING.md)
 
 ## What is Atlantis?
-A self-hosted golang application that listens for Terraform pull request events via webhooks.
+
+A self-hosted Go application that listens for Terraform and OpenTofu pull request events via webhooks.
 
 ## What does it do?
-Runs `terraform plan`, `import`, `apply` remotely and comments back on the pull request with the output.
+
+Runs `terraform plan`, `import`, `apply` (or `tofu plan`, `import`, `apply`) remotely and comments back on the pull request with the output.
 
 ## Why should you use it?
-* Make Terraform changes visible to your whole team.
-* Enable non-operations engineers to collaborate on Terraform.
-* Standardize your Terraform workflows.
+
+- Make Terraform and OpenTofu changes visible to your whole team.
+- Enable non-operations engineers to collaborate on infrastructure as code.
+- Standardize your Terraform and OpenTofu workflows.
+- Support both Terraform and OpenTofu in the same instance.
 
 ## Stargazers over time
 

runatlantis.io/docs/repo-level-atlantis-yaml.md

@@ -273,12 +273,28 @@ by the `--default-tf-version` flag, then set the `terraform_distribution` key:
 ```yaml
 version: 3
 projects:
-   - dir: project1
-     terraform_distribution: opentofu
+- dir: project1
+  terraform_distribution: opentofu
+- dir: project2
+  terraform_distribution: terraform
 ```
 
 Atlantis will automatically download and use this distribution. Valid values are `terraform` and `opentofu`.
 
+When using OpenTofu, you can also specify a specific version:
+
+```yaml
+version: 3
+projects:
+- dir: opentofu-project
+  terraform_distribution: opentofu
+  terraform_version: 1.9.0
+```
+
+:::tip OpenTofu Migration
+If you're migrating from Terraform to OpenTofu, you can run both in the same Atlantis instance by specifying different distributions per project. This allows for gradual migration.
+:::
+
 ### Terraform Versions
 
 If you'd like to use a different version of Terraform than what is in Atlantis'