lintnet - General purpose linter powered by Jsonnet

This presentation is about my OSS project named lintnet.

https://lintnet.github.io/

lintnet is a general-purpose linter for structured configuration data, powered by Jsonnet.
In this presentation, you will learn what lintnet is and why you should use it.

https://lintnight.connpass.com/event/319202/

Links:
https://jsonnet.org/
Native functions: https://lintnet.github.io/docs/lint-rule/native-function/
https://github.com/lintnet/renovate-config
Official Modules: https://github.com/orgs/lintnet-modules/repositories
Conftest: https://www.conftest.dev/
Conftest - Sharing policies: https://www.conftest.dev/sharing/

Transcript

1. lintnet - General purpose linter powered by Jsonnet Shunsuke Suzuki 2024-06-07 Lint Night#3 1
2. Self introduction Shunsuke Suzuki Platform Engineer at Mercari Platform Group GitHub: suzuki-shunsuke X: szkdash 2
3. My OSS • aqua - Declarative CLI Version Manager written in Go • tfcmt - Notify the result of terraform to GitHub pull requests • tfaction - GitHub Actions for Terraform Monorepo • etc 3
4. Overview • Introduction of my new OSS lintnet • What’s lintnet? 4
5. What’s lintnet? • https://lintnet.github.io/ • General purpose linter for structured configuration data powered by Jsonnet • CLI like Conftest • Single binary written in Go. No dependency and easy to install • lintnet itself has no lint rule. You can define lint rules and lint files 5
6. General purpose • k8s, Terraform, GitHub Actions, CircleCI, etc • No need to use different linters and develop linters from scratch • Support various data format • Programing languages aren't supported 6
7. Jsonnet • Superset of JSON for dynamic configuration • Generate JSON dynamically https://jsonnet.org/ 7
8. Jsonnet • Popular • Simple - low learning cost • Powerful - if, for, function, std lib, import, native function, etc • Secure - restrict access to filesystem and network and OS command 8
9. Extend Jsonnet by Native functions • lintnet extends Jsonnet by adding native functions • https://lintnet.github.io/docs/lint-rule/native-function/ 9
10. Module • Easy to reuse and distribute lint rules • Reuse is just referring to modules in config or lint files • Distribution is just publishing Jsonnet files in GitHub repositories • Hopefully many awesome modules are published by community so that we can achieve awesome lint easily 10
11. Auto module update by Renovate • https://github.com/lintnet/renovate-config • lintnet’s Official Renovate Preset 11
12. Official Modules • Official Modules • e.g. ◦ lintnet-modules/ghalint - Port of ghalint ◦ lintnet-modules/nllint - Port of nllint 12
13. Extra features • Test lint rules • Parameterize lint rules • Lint across multiple files • Customize Output • Control the result by error level 13
14. How to achieve lint by Jsonnet 14
15. Limitation • Utilize the location of lint errors ◦ reviewdog and editor integration ◦ Output code where error occurs • Auto fix • Disable some lint rules by code annotation • Lint of programming languages It's difficult to support them as a general purpose linter 15
16. How to use lintnet 1. Create a configuration file lintnet.jsonnet 2. Define lint rules by Jsonnet 3. Test rules by Jsonnet 4. Run lintnet lint command 16
17. Configuration file (lintnet.jsonnet) $ lintnet init 17
18. Lint rule hello.jsonnet 18
19. Test hello_test.jsonnet *_test.jsonnet A list of test cases test data + expected lint result $ lintnet test 19
20. Run lintnet 20
21. Comparison with Conftest 21
22. Conftest • https://www.conftest.dev/ • Utility to help you write tests against structured configuration data • Use Rego as a Policy Language • Cover various lint rules with one tool 22
23. Issues of Conftest • Low reusability of policies ◦ People develop similar lint rules independently ◦ No standard way to share policies across multiple repositories ◦ conftest push/pull is a low level API ◦ https://www.conftest.dev/sharing/ 23
24. Compared with Conftest • Easy to reuse and distribute lint rules by Module • Standardized workflow by Configuration file and sub commands 24
25. Jsonnet vs Rego • It is difficult to compare them objectively • This is up to users • Some people feel Rego is difficult and Jsonnet is easier than Rego 25
26. Summary • lintnet is a general purpose linter powered by Jsonnet • Users don’t need to use many different linters • Developers can focus on developing lint rules • lintnet enables us to reuse and distribute lint rules by Module 26