logger

• ✅ Binding the popular Rust logging library spdlog-rs via FFI for Mojo usage.
• ✅ Redesigned API inspired by Python's loguru logging library for improved usability.

Logger Mojo

🐝 Binding spdlog-rs logging library for mojo 🔥

简体中文 | English

Package Contents

Project	Package	Host	Rank	Description
✅ spdlog-ffi	libspdlog_ffi	prefix.dev	⭐️⭐️⭐️	spdlog-rs ffi package
✅ spdlog	spdlog	prefix.dev	⭐️⭐️⭐️⭐️	spdlog-mojo package

Features

• ✅ Support logging to: console, file, stdout, stderr
• ✅ Support custom log format
• ✅ Support log level configuration
• ✅ Support colored logs

Usage

• Import dependencies:

# First add channel sources, including spdlog-ffi package and spdlog package
channels = [
    "https://conda.modular.com/max-nightly",
    "https://repo.prefix.dev/better-ffi", # contains spdlog-ffi package
    "https://repo.prefix.dev/better-mojo", # contains spdlog mojo package
    "conda-forge",
]

# Add dependency packages
[dependencies]
mojo = ">=1.0.0b2.dev2026052706,<2" # TODO X: fix version inconsistency issue!!!

# FFI dependency
libspdlog_ffi = ">=0.1.0,<0.2"

# Mojo package dependency
# spdlog = { git = "https://github.com/better-mojo/logger.git", branch = "main" }
spdlog = ">=0.1.2,<0.2"

• ✅ Simple example:

from spdlog import get_logger


def main() raises -> None:
    var logger = get_logger()

    logger.info("Hello, World!")
    logger.debug("Processing item {} of {}", "5", "100")
    logger.warn("Disk usage is at {}%", "85")

• ✅ run:

# Run logging example
pixi run mojo -I . examples/logger.mojo

• ✅ Complete example examples/try-uuid
  • Includes complete package dependency import methods

# Install dependencies
pixi install

# Run
pixi run mojo src/main.mojo

File Logging Example

• examples/logger_file.mojo
  • Includes complete package dependency import methods
  • Includes file logging example

Development Environment

Install Dependencies

• Install Taskfile: build tool
• Install Rust
• Install pixi
• Install rattler-build: package management tool, compile + publish rust binary packages
• Install mojo

task setup

Build and Debug

• ✅ Build and debug spdlog-ffi package

# Run examples
task ffi:r

# Build spdlog-ffi package
task ffi:b

# Release spdlog-ffi package
task ffi:rel

• ✅ Build and debug examples

# Run examples
task run:logger

Release and Publish to Prefix.dev

• ✅ https://prefix.dev/channels/better-ffi
• ✅ https://prefix.dev/channels/better-mojo
• ✅ Taskfile

# Publish spdlog-ffi package to prefix.dev
task m:q:rs

# Publish spdlog package to prefix.dev
task m:q:mojo

• ✅ Compile and release Linux version, based on orbstack virtual machine
  • Note: each time you need to publish the ffi library for 3 OS versions to prefix.dev first, then publish the spdlog package. (dependency order)

# List available virtual machines
orbctl list 

# Connect to linux-aarch64 architecture virtual machine, execute compile + publish
orbctl run -m u22dev

# Connect to linux-64 architecture virtual machine, execute compile + publish
orbctl run -m u22build

Reference

Mojo FFI Packages

• ✅ https://github.com/better-mojo/uuid
• ✅ https://github.com/ehsanmok/sqlite

Python loguru

• ✅ https://github.com/delgan/loguru

Rust spdlog

• ✅ https://github.com/SpriteOvO/spdlog-rs

Rust FFI

• ✅ https://github.com/getditto/safer_ffi
• ✅ https://github.com/f0cii/diplomat
  • https://github.com/rust-diplomat/diplomat
  • https://rust-diplomat.github.io/book/
• ✅ https://github.com/mozilla/uniffi-rs
• ✅ https://rustwiki.org/zh-CN/std/ffi/struct.CString.html#examples