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Overview

Bootstrapping is the process of configuring a Flower FL project to work with Syft-Flwr. This transforms a standard Flower project into a privacy-preserving federated learning setup that can run across multiple datasites.

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Prerequisites

Before bootstrapping, you need:
  • An existing Flower project with pyproject.toml
  • Valid datasite email addresses for participants
  • An aggregator (server) email address
  • Python 3.9 or higher

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Basic Bootstrap Process

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Using the CLI

The simplest way to bootstrap a project is using the syft_flwr CLI: 
syft_flwr bootstrap /path/to/flower-project \
  --aggregator data-scientist@openmined.org \
  --datasites data-owner-1@hospital.org,data-owner-2@clinic.com

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Interactive Mode

If you don’t provide the required arguments, the CLI will prompt you: 
syft_flwr bootstrap /path/to/flower-project
# Enter the datasite email of the Aggregator (Flower Server): data-scientist@openmined.org
# Enter a comma-separated email of datasites of the Flower Clients: data-owner-1@hospital.org,data-owner-2@clinic.com

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Using Python API

from pathlib import Path
from syft_flwr.bootstrap import bootstrap

project_dir = Path("./my-fl-project")
aggregator = "data-scientist@openmined.org"
datasites = [
    "data-owner-1@hospital.org",
    "data-owner-2@clinic.com"
]

bootstrap(
    flwr_project_dir=project_dir,
    aggregator=aggregator,
    datasites=datasites
)

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Transport Configuration

Syft-Flwr supports two transport mechanisms:
Uses local SyftBox client with RPC and end-to-end encryption.
bootstrap(
    flwr_project_dir=project_dir,
    aggregator=aggregator,
    datasites=datasites,
    transport="syftbox"  # Default
)
Features:
  • End-to-end encryption enabled by default
  • Uses SyftBox Go client for file sync
  • RPC communication via futures database
  • Best for production deployments

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Auto-Detection

When transport=None, Syft-Flwr automatically detects the environment: 
bootstrap(
    flwr_project_dir=project_dir,
    aggregator=aggregator,
    datasites=datasites,
    transport=None  # Auto-detect
)
# In Colab: Uses "p2p"
# Otherwise: Uses "syftbox"

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What Bootstrap Does

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1. Validates Project Structure

Bootstrap verifies:
  • pyproject.toml exists in the project directory
  • main.py doesn’t already exist (to avoid overwriting)
  • All email addresses are valid datasites
# bootstrap.py:86-98
def __validate_flwr_project_dir(flwr_project_dir: Union[str, Path]) -> Path:
    flwr_pyproject = flwr_project_dir / "pyproject.toml"
    flwr_main_py = flwr_project_dir / "main.py"

    if flwr_main_py.exists():
        raise FileExistsError(f"File '{flwr_main_py}' already exists")

    if not flwr_project_dir.exists():
        raise FileNotFoundError(f"Directory '{flwr_project_dir}' not found")

    if not flwr_pyproject.exists():
        raise FileNotFoundError(f"File '{flwr_pyproject}' not found")

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2. Updates pyproject.toml

Bootstrap adds Syft-Flwr configuration to your pyproject.toml: 
[project]
name = "my-fl-project"
dependencies = [
    "syft_flwr==0.1.0",  # Added automatically
    # ... your existing dependencies
]

[tool.syft_flwr]
app_name = "aggregator@example.com_my-fl-project_1234567890"
datasites = ["client1@example.com", "client2@example.com"]
aggregator = "aggregator@example.com"
transport = "syftbox"  # or "p2p"

[tool.flwr.app.config]
partition-id = 0
num-partitions = 1

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3. Generates main.py

Creates the entry point that orchestrates your FL workflow: 
# Generated main.py structure
import sys
from pathlib import Path
from syft_flwr.run import syftbox_run_flwr_client, syftbox_run_flwr_server

def main():
    project_dir = Path(__file__).parent
    
    if "-s" in sys.argv or "--server" in sys.argv:
        syftbox_run_flwr_server(project_dir)
    else:
        syftbox_run_flwr_client(project_dir)

if __name__ == "__main__":
    main()

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Project Structure

After bootstrapping, your project structure looks like: 
my-fl-project/
├── pyproject.toml          # Updated with syft_flwr config
├── main.py                 # Generated entry point
├── my_fl_project/
│   ├── __init__.py
│   ├── server_app.py      # Your Flower ServerApp
│   ├── client_app.py      # Your Flower ClientApp
│   └── task.py            # Your ML logic
└── README.md

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Email Validation

Datasite and aggregator emails must be valid: 
# Valid examples
aggregator = "data-scientist@openmined.org"  # ✓
datasites = [
    "client1@hospital.edu",  # ✓
    "user@clinic.co.uk"      # ✓
]

# Invalid examples
aggregator = "invalid-email"           # ✗ No @ or domain
datasites = ["@example.com"]           # ✗ No local part

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Complete Example

Here’s a full workflow from creating a Flower project to bootstrapping:
1

Create Flower Project

flwr new my-fl-project --framework pandas
cd my-fl-project
2

Bootstrap with Syft-Flwr

syft_flwr bootstrap . \
  --aggregator data-scientist@openmined.org \
  --datasites hospital1@med.org,hospital2@med.org
3

Verify Configuration

cat pyproject.toml | grep syft_flwr
ls main.py  # Should exist now

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Troubleshooting

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”main.py already exists”

Bootstrap won’t overwrite existing main.py. Remove it first: 
rm main.py
syft_flwr bootstrap .

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“Invalid datasite” Error

Ensure all emails match the pattern name@domain.tld: 
# bootstrap.py:131-136
if not is_valid_datasite(aggregator):
    raise ValueError(f"'{aggregator}' is not a valid datasite")

for ds in datasites:
    if not is_valid_datasite(ds):
        raise ValueError(f"{ds} is not a valid datasite")

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“pyproject.toml not found”

Make sure you’re in a valid Flower project directory: 
ls pyproject.toml  # Must exist
cat pyproject.toml | grep "tool.flwr"  # Should have Flower config

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Next Steps

Run Simulations

Test your bootstrapped project locally

Transport Configuration

Deep dive into transport options

Multi-Client Setup

Deploy across multiple datasites

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