fyrer

A declarative, fast and lightweight monorepo tool that runs multiple dev servers and build tasks concurrently.

fyrer reads a fyrer.yml file describing projects and their tasks, resolves the dependency graph between tasks, runs each level of the graph concurrently, and streams every task's output through a colorized, prefixed logger. Long-running tasks can be restarted automatically when their watched input files change.

Installation

Install using cargo

cargo install fyrer

Build from source

git clone https://github.com/07calc/fyrer
cd fyrer
cargo build --release
cargo install --path .

Usage

fyrer looks for a fyrer.yml file in the current directory. A full example is available at fyrer.example.yml.

# Run every task
fyrer run

# Run a single task or every task with a given name
fyrer run web:dev
fyrer run build

# Show the execution plan without running anything
fyrer run dev --dry-run

# List every project and its tasks
fyrer list

# Point at a different configuration file
fyrer --config path/to/fyrer.yml run

Configuration

version: 1                       # config format version (required)
env:                             # variables shared by every project
  NODE_ENV: development
projects:                        # projects that make up the monorepo
  - name: web                    # unique project name
    root: ./apps/web             # relative project root
    env:                         # variables shared by every task
      PORT: "3000"
    env_path: .env               # .env file path, relative to root
    tasks:
      dev:
        cmd: bun run dev         # shell command to run
        depends_on: [build]      # tasks that must run first
        inputs: [src/**]         # globs of watched input files
        outputs: [dist/**]       # globs of produced output files
        ignore: [node_modules/**]  # globs excluded from watching
        cache: false             # allow skipping when outputs are fresh
        restart:
          strategy: FileChange   # FileChange | OnFailure | Never
          delay: 300             # debounce before restarting (ms)
        env:                     # per-task variables (highest precedence)
          PORT: "8080"

Environment precedence

From lowest to highest: root-level env, project-level env, the project's .env file, then task-level env.

Restart strategies

• FileChange – restart whenever a watched input file changes (requires inputs).
• OnFailure – restart after the process exits with a failure.
• Never – never restart.

Features

• Run multiple development servers and build tasks concurrently
• Declarative YAML-based configuration with validation
• Dependency-aware topological ordering
• Automatic .env file parsing with per-task overrides
• Colorized, prefixed log output
• Optional file-watching with automatic restarts and debouncing
• Graceful shutdown on SIGINT/SIGTERM, killing spawned process groups

License

MIT