# Tach [![downloads](https://static.pepy.tech/badge/tach/month)](https://pepy.tech/project/tach) [![version](https://img.shields.io/pypi/v/tach.svg)](https://pypi.Python.org/pypi/tach) [![license](https://img.shields.io/pypi/l/tach.svg)](https://pypi.Python.org/pypi/tach) [![python](https://img.shields.io/pypi/pyversions/tach.svg)](https://pypi.Python.org/pypi/tach) [![ci](https://github.com/gauge-sh/tach/actions/workflows/ci.yml/badge.svg)](https://github.com/gauge-sh/tach/actions/workflows/ci.yml) [![basedpyright - checked](https://img.shields.io/badge/basedpyright-checked-ffc000)](https://docs.basedpyright.com) [![ruff](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json)](https://github.com/astral-sh/ruff) Tach is a Python tool to enforce dependencies and interfaces, written in Rust. Tach is inspired by the [modular monolith](https://www.milanjovanovic.tech/blog/what-is-a-modular-monolith) architecture. [Docs](https://docs.gauge.sh)
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https://github.com/user-attachments/assets/11eec4a1-f80a-4f13-9ff3-91a9760133b6 Tach can enforce: - πŸ“‹ Imports only come from [declared dependencies](https://docs.gauge.sh/usage/configuration#modules) - 🀝 Cross-module calls use the [public interface](https://docs.gauge.sh/usage/configuration#interfaces) - ⛓️‍πŸ’₯ [No cycles](https://docs.gauge.sh/usage/configuration) in the dependency graph Tach is: - 🌎 Open source - 🐍 Installable via pip - πŸ”§ Able to be adopted incrementally - ⚑ Implemented with no runtime impact - ♾️ Interoperable with your existing systems ## Getting Started ### Installation ```bash pip install tach ``` ### Setup Tach will guide you through initial project setup. Run: ```bash tach init ``` After an introductory message, you will see a file tree interface allowing you to interactively configure your project. Use the arrow keys to navigate, and mark each module boundary with 'Enter'. You can mark all of your top-level Python packages, or just a few that you want to track. FAQ: [What is a module?](https://docs.gauge.sh/usage/faq#what-is-a-module%3F) If your Python code lives below your project root, or if you are working in a monorepo with multiple Python packages, mark your Python [source roots](https://docs.gauge.sh/usage/configuration#source-roots) using the 's' key. ### Enforcement Tach comes with a cli command to enforce the boundaries that you just set up! From the root of your Python project, run: ```bash tach check ``` You will see: ```bash βœ… All modules validated! ``` You can validate that Tach is working by: 1. Removing an item from the `depends_on` key in `tach.toml`, or marking it as [deprecated](https://docs.gauge.sh/usage/deprecate) 2. By adding an import between modules that didn't previously import from each other. Give both a try and run `tach check` again. This will generate an error: ```bash ❌ tach/check.py[L8]: Cannot use 'tach.filesystem'. Module 'tach' cannot depend on 'tach.filesystem'. ``` Each error indicates an import which violates your dependencies. If your terminal supports hyperlinks, click on the file path to go directly to the error. When an error is detected, `tach check` will exit with a non-zero code. It can be easily integrated with CI/CD, [Pre-commit hooks](https://docs.gauge.sh/usage/commands#tach-install), and [VS Code](https://marketplace.visualstudio.com/items?itemName=detachhead.dtach), and more! ### Extras Visualize your dependency graph. ```bash tach show [--web] ``` Tach will generate a graph of your dependencies. Here's what this looks like for Tach: ![tach show](docs/assets/tach_show.png) Note that this graph is generated remotely with the contents of your `tach.toml` when running `tach show --web`. If you would like to use the [GraphViz DOT format](https://graphviz.org/about/) locally, simply running `tach show` will generate `tach_module_graph.dot` in your working directory. You can view the dependencies and usages for a given path: ```bash tach report my_package/ # OR tach report my_module.py ``` e.g.: ```bash > tach report python/tach/filesystem [Dependencies of 'python/tach/filesystem'] python/tach/filesystem/install.py[L6]: Import 'tach.hooks.build_pre_commit_hook_content' python/tach/filesystem/project.py[L5]: Import 'tach.constants.CONFIG_FILE_NAME' ... ------------------------------- [Usages of 'python/tach/filesystem'] python/tach/cache/access.py[L8]: Import 'tach.filesystem.find_project_config_root' python/tach/cache/setup.py[L7]: Import 'tach.filesystem.find_project_config_root' ... ``` Tach also supports: - [Public interfaces for modules](https://docs.gauge.sh/usage/interfaces/) - [Deprecating individual dependencies](https://docs.gauge.sh/usage/deprecate) - [Layered architecture](https://docs.gauge.sh/usage/layers) - [Incremental adoption](https://docs.gauge.sh/usage/unchecked-modules) - [Generating JSON dependency maps](https://docs.gauge.sh/usage/commands#tach-map) - [Monorepos and namespace packages](https://docs.gauge.sh/usage/configuration#source-roots) - [Domain ownership](https://docs.gauge.sh/usage/configuration#tach-domain-toml) - [Inline 'ignore' comments](https://docs.gauge.sh/usage/tach-ignore) - [Pre-commit hooks](https://docs.gauge.sh/usage/commands#tach-install) More info in the [docs](https://docs.gauge.sh/). If you have any feedback, we'd love to talk! If you have any questions or run into any issues, let us know by submitting a [Github Issue](https://github.com/gauge-sh/tach/issues)! --- ### Contributors