zetten 1.0.4

Fast task runner for Python projects

Zetten

Zetten is a fast, deterministic task runner for Python backend projects, written in Rust. It provides a reliable way to run common backend tasks - tests, linters, type checks, builds - using a single execution engine that behaves the same locally and in CI. Zetten replaces ad-hoc setups built from Makefiles, shell scripts, nox/tox, and CI YAML glue with a small, explicit, and predictable tool. Zetten is inspired by tools like make, nox, just, and cargo, but is designed specifically for modern Python backend workflows.

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Why Zetten

Python backend projects often rely on a mix of:

• Makefiles
• shell scripts
• tox / nox
• CI YAML logic

These approaches are flexible, but they are often:

• non-deterministic
• slow as projects grow
• hard to reason about
• inconsistent between local runs and CI

Zetten focuses on a small set of guarantees:

• The same inputs always produce the same results
• Tasks only run when their inputs change
• Independent tasks run in parallel
• Local and CI execution behave identically

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Features

• Fast execution using a Rust-based core
• Deterministic task caching based on input hashing
• Python virtual environment awareness
• Automatic environment detection without manual activation
• Parallel task execution using a worker pool
• Task dependency execution using a DAG model
• Structured logging and progress reporting
• Clear and consistent exit code semantics

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What Zetten Is (and Is Not)

Zetten is

• A task runner for Python backend projects
• A local development and CI execution tool
• Deterministic and cache-aware
• CLI-first

Zetten is not

• A framework
• A workflow engine
• A job queue
• A replacement for linters or test frameworks
• A runtime dependency of your application

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Quick Start

Install Zetten:

pip install zetten

Initiate a project:

zetten init

Define tasks in pyproject.toml:

[tool.zetten.tasks.test]
cmd = "pytest"
inputs = ["src/", "tests/"]

[tool.zetten.tasks.lint]
cmd = "ruff check src"
inputs = ["src/"]

Define tasks in zetten.toml:

[tasks.test]
cmd = "pytest"
inputs = ["src/", "tests/"]

[tasks.lint]
cmd = "ruff check src"
inputs = ["src/"]

Run tasks:

zetten run test
zetten run lint test

Zetten will only re-run tasks when their inputs change.

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Configuration Model

Configuration is explicit by design:

• No templating
• No conditionals
• No implicit behavior

Configuration lives in:

• pyproject.toml (preferred)
• zetten.toml (for legacy or minimal projects)

If no configuration is found, Zetten will explain how to fix it.

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Commands

• zetten run — execute tasks deterministically
• zetten watch — re-run tasks on input changes
• zetten graph — inspect the task dependency graph
• zetten doctor — diagnose configuration and environment issues
• All commands produce stable, CI-safe output with well-defined exit codes.

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Status

Zetten is in v0.1 and is feature-complete for its initial design. Core semantics - execution, caching, exit codes, configuration - are stable.

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Documentation

Full documentation is available at: Github Wiki

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Contributing and Feedback

Zetten is intentionally minimal and opinionated. Feedback is welcome, especially around:

• Developer experience
• CI usage
• Installation friction
• Missing but essential workflows.

Please open an issue or discussion on GitHub before proposing large changes.