cdk/DEVELOPMENT.md

Development Guide

This guide will help you set up your development environment for working with the CDK repository.

Prerequisites

Before you begin, ensure you have:

• Git installed on your system
• GitHub account
• Basic familiarity with command line operations

Initial Setup

1. Fork and Clone the Repository

1. Navigate to the CDK repository on GitHub
2. Click the "Fork" button in the top-right corner
3. Clone your forked repository:

git clone https://github.com/YOUR-USERNAME/cdk.git
cd cdk

2. Install Nix

CDK uses Nix for building, CI, and managing dev environment. Note: only Nix (the language & package manager) and not the NixOS (the Linux distribution) is needed. Nix can be installed on any Linux distribution and macOS.

While Nix is preferred as it ensures a consistent and reproducible environment for all developers, it is not strictly required to use Nix to build CDK.

Install Nix

You have 2 options to install nix:

• RECOMMENDED: The Determinate Nix Installer
• The official installer

Example:

> nix --version
nix (Nix) 2.9.1

The exact version might be different.

Enable nix flakes

If you installed Nix using the "determinate installer" you can skip this step. If you used the "official installer", edit either ~/.config/nix/nix.conf or /etc/nix/nix.conf and add:

experimental-features = nix-command flakes

If the Nix installation is in multi-user mode, don’t forget to restart the nix-daemon.

Alternative Setup Without Nix

While Nix is preferred as it ensures a consistent and reproducible environment for all developers, it is not strictly required to use Nix to build CDK. You can also set up your environment manually.

Installing Rust via rustup

To build CDK without Nix, you'll need to install Rust manually:

1. Install rustup by following the instructions at https://www.rust-lang.org/tools/install

2. Once rustup is installed, you can install the required Rust version:

rustup install stable
rustup default stable

3. Install required tools:

# For building cdk-mintd, you'll need protobuf compiler
# On Ubuntu/Debian:
sudo apt install protobuf-compiler

# On macOS with Homebrew:
brew install protobuf

# On other systems, please refer to your package manager or
# https://grpc.io/docs/protoc-installation/

Building and Running CDK Components

Building cdk-cli

To build the CDK command-line interface:

cargo build --bin cdk-cli --release

To run cdk-cli directly without building:

cargo run --bin cdk-cli -- --help

Building cdk-mintd

To build the CDK mint server:

cargo build --bin cdk-mintd --release

To run cdk-mintd directly without building:

cargo run --bin cdk-mintd

Note: For cdk-mintd, you need to have the protobuf compiler installed as it's required for some dependencies.

Use Nix Shell

  nix develop -c $SHELL  

Regtest Environment

For testing and development, CDK provides a complete regtest environment with Bitcoin, Lightning Network nodes, and CDK mints.

Quick Start

just regtest  # Starts full environment with mprocs TUI

This provides:

• Bitcoin regtest node
• 4 Lightning Network nodes (2 CLN + 2 LND)
• 2 CDK mints (one connected to CLN, one to LND)
• Real-time log monitoring via mprocs
• Helper commands for testing Lightning payments and CDK operations

Comprehensive Guide

See REGTEST_GUIDE.md for complete documentation including:

• Detailed setup and usage instructions
• Development workflows and testing scenarios
• mprocs TUI interface guide
• Troubleshooting and advanced usage

Common Development Tasks

Building the Project

just build

Running Unit Tests

just test

Running Integration Tests

just itest REDB/SQLITE/MEMORY

NOTE: if this command fails on macos change the nix channel to unstable (in the flake.nix file modify nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11"; to nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";)

Running Format

just format

Running Clippy

just clippy

Running final check before commit

just final-check

Best Practices

1. Branch Management

   • Create feature branches from main
   • Use descriptive branch names: feature/new-feature or fix/bug-description

2. Commit Messages

   • Follow conventional commits format
   • Begin with type: feat:, fix:, docs:, chore:, etc.
   • Provide clear, concise descriptions

3. Testing

   • Write tests for new features
   • Ensure all tests pass before submitting PR
   • Include integration tests where applicable

Troubleshooting

Common Issues

1. Development Shell Issues
   • Clean Nix store: nix-collect-garbage -d
   • Remove and recreate development shell

Getting Help

• Open an issue on GitHub
• Check existing issues for similar problems
• Include relevant error messages and system information
• Reach out in Matrix Invite link

Contributing

1. Create a feature branch
2. Make your changes
3. Run tests and formatting
4. Submit a pull request
5. Wait for review and address feedback

Backporting Changes

CDK uses an automated backport bot to help maintain stable release branches. This section explains how the backport process works.

How the Backport Bot Works

The backport bot creates pull requests to backport merged changes from main to stable release branches. You control which branches to backport to by adding labels to your PR.

Available Target Branches:

• v0.10.x
• v0.11.x
• v0.12.x
• v0.13.x

Using Backport Labels

To backport a PR to specific stable branches, add labels to your PR before or after merging:

Label Format:

• backport v0.13.x - backports to v0.13.x branch
• backport v0.12.x - backports to v0.12.x branch
• Add multiple labels to backport to multiple branches

Example Workflow:

1. Create and merge your PR to main
2. Add label backport v0.13.x to the PR
3. The bot automatically creates a backport PR for the v0.13.x branch
4. Review and merge the backport PR
5. Repeat for other branches as needed

When to Add Labels:

• Add labels before merging - backport PRs are created automatically on merge
• Add labels after merging - backport PRs are created when you add the label
• You can add multiple backport labels at once

When Backports Fail

Sometimes the backport bot cannot automatically create a backport PR due to merge conflicts or other issues. When this happens:

1. The bot automatically creates a GitHub issue labeled with backport
2. The issue will contain details about the original PR and which branch(es) failed
3. You'll need to manually create the backport PR for the failed branch

Manual Backporting Process:

# Checkout the target stable branch
git checkout v0.13.x
git pull origin v0.13.x

# Create a new branch for the backport
git checkout -b backport-pr-NUMBER-to-v0.13.x

# Cherry-pick the commits from the original PR
git cherry-pick COMMIT_HASH

# Resolve any conflicts if they occur
# Then push and create a PR
git push origin backport-pr-NUMBER-to-v0.13.x

Best Practices for Backporting

1. Label Appropriately: Only add backport labels for changes that should be in stable branches
2. Keep PRs Focused: Smaller, focused PRs are easier to backport automatically
3. Review Backport PRs: Always review automatically created backport PRs to ensure they're appropriate
4. Test Backports: Run tests on backport PRs just like regular PRs
5. Address Conflicts Promptly: If a backport fails, address it promptly or close the issue with an explanation

When NOT to Backport

Not all changes should be backported to stable branches. Don't add backport labels for:

• Breaking API changes
• New features that aren't needed in older versions
• Changes that don't apply to older version branches
• Large refactorings
• Experimental or unstable features

If a backport isn't appropriate, simply don't add the backport label to the PR.

Additional Resources

• Nix Documentation
• Contributing Guidelines

License

Refer to the LICENSE file in the repository for terms of use and distribution.