How OpenTofu uses LSP to power its text editors plugins

Talk given at KubeCon NA 2025 on OpenTofu day.

Transcript

2. Diógenes Fernandes - OpenTofu Maintainer How OpenTofu uses LSP to power its text editors plugins Sponsored by Gruntwork CC BY-SA 4.0
3. Text Editor Plugins? Neovim VS Code Kate
4. What is going to be shown today? • What is LSP and how it works • Tofu-ls features: ◦ Hover ◦ Schema Validation
5. LSP? https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification • LSP stands for Language Server Protocol • Communication between text editors and language servers • Created in 2015 by Microsoft for VS Code • Open-sourced in 2016 with the participation of CodeEnvy and RedHat • Turns a M x N problem into a M + N problem (quote by TJ DeVries) ◦ M editors ◦ N language servers
6. JSON-RPC 2.0 Request Response
7. Meet Tofu-LS server • Released in a lot of different package managers • https://github.com/opentofu/tofu-ls • Fork of https://github.com/hashicorp/terraform-ls
8. Features
9. initialize
10. initialize
11. Hover
12. Hover Hover
13. opentofu-schema
14. opentofu-schema - Body vs BodySchema AST vs Specification
15. HCL library - hcl-lang
16. Body
17. Hover Hover
18. Hover Hover
19. Schema Validation
20. Schema Validation
21. Schema Validation - Bundled providers
22. Schema Validation - Bundled and others
23. Schema Validation - hcl-lang
24. Schema Validation - hcl-lang
25. Schema Validation - hcl-lang
26. Pull vs Push Diagnostics
27. Schema Validation
28. What's next? • Refactor capabilities (like renaming symbols) • Improving references, definitions, implementations… • Improving performance issues in big projects
29. That's it! • Special thanks to ◦ Gruntwork ◦ Gamunu Balagalla - vscode-opentofu ◦ Ilia @Gogotchuri - OpenTofu Maintainer ◦ OpenTofu maintainers • For support ◦ https://github.com/opentofu/tofu-ls • Talk to us! ◦ https://opentofu.org/slack/
30. Questions?