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This guide walks you through setting up your local development environment for GOV.UK Notify Admin, a Flask-based Python admin frontend.

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Prerequisites

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Python 3.13

GOV.UK Notify Admin runs Python 3.13 in production. Ensure you have Python 3.13 installed on your system.

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Node.js 24

The project uses Node.js version 24 (specified in .nvmrc).

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Install Node.js with Homebrew

brew install node
nvm is a tool for managing different versions of Node.js. Follow the installation guidance on nvm’s GitHub repository. Once installed, switch to the project’s Node.js version: 
nvm use
If you don’t have Node.js 24 installed, nvm will tell you how to install it.

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Initial Setup

1

Install uv for Python dependency management

The project uses uv for Python dependency management.
curl -LsSf https://astral.sh/uv/install.sh | sh
See the uv installation docs for alternative installation methods.
2

Install pre-commit hooks

The project uses pre-commit to ensure committed code meets formatting standards and makes basic fixes automatically.Install pre-commit system-wide:
brew install pre-commit
Then install the hooks in this repository:
pre-commit install --install-hooks
The pre-commit configuration (.pre-commit-config.yaml) includes:
  • Trailing whitespace removal
  • End-of-file fixer
  • YAML validation
  • Debug statement detection
  • Ruff linting and formatting
3

Create environment.sh

Create an environment.sh file in the root directory with required environment variables:
echo "
export NOTIFY_ENVIRONMENT='development'
export FLASK_APP=application.py
export FLASK_DEBUG=1
export WERKZEUG_DEBUG_PIN=off
" > environment.sh
This file sets up:
  • NOTIFY_ENVIRONMENT: Identifies the environment as development
  • FLASK_APP: Points to the main application file
  • FLASK_DEBUG: Enables Flask debug mode for auto-reload
  • WERKZEUG_DEBUG_PIN: Disables the Werkzeug debugger PIN
4

Bootstrap the application

Run the bootstrap command to install all dependencies and build the frontend:
make bootstrap
This command:
  1. Generates a version file (app/version.py)
  2. Installs Python dependencies from requirements_for_test.txt using uv
  3. Installs Node.js dependencies using npm ci --no-audit
  4. Builds the frontend assets with npm run build

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AWS Credentials (Optional)

To run certain parts of the application (such as uploading letters), you’ll need appropriate AWS credentials. See the Notify manuals wiki for details on setting up AWS credentials for local development.

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Next Steps

With your environment set up, you’re ready to:

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