In Progress

Deacon

A fast, lightweight Rust implementation of the DevContainer CLI for reproducible development environments.

Deacon robot mascot - a tall elegant silver robot, surrounded by Rust and container icons

Overview

Deacon is a production-ready Rust implementation of the Development Containers CLI, following the containers.dev specification. It provides DevOps teams and developers with a fast, cross-platform tool for managing containerized development environments without requiring Node.js. With a startup time under 100ms and a ~40MB binary, Deacon brings the full power of DevContainers to CI/CD pipelines and teams seeking lightweight, reproducible workflows.

Key Features

Container Lifecycle Management - Full up/exec/down commands with all lifecycle phases (onCreate, postCreate, postStart, postAttach), idempotent operations, and container state persistence.
Configuration Resolution - Complete devcontainer.json parsing with variable substitution, extends chains for layered configurations, and Docker Compose multi-service orchestration.
OCI Feature System - Install, test, package, and publish reusable features via OCI registries with dependency resolution, parallel installation, and lockfile support for reproducible builds.
Template Management - Create and publish parameterized project templates with scaffolding options, metadata generation, and registry publication for team sharing.
Container Image Building - Dockerfile-based builds from devcontainer configs with BuildKit integration for secrets, SSH forwarding, caching, and multi-architecture support.
System Diagnostics - Built-in doctor command validates Docker availability, disk space, CPU, and memory requirements with JSON output for automation.

Use Cases

Deacon excels in these scenarios:

Standardizing team development environments with version-controlled configurations
CI/CD pipeline integration with fast startup and JSON output modes
Open-source project onboarding with single-command setup
Feature development, testing, and publishing to OCI registries
Multi-platform container builds with BuildKit integration
Migrating from VS Code Dev Containers to CLI-first workflows

Technical Highlights

Built in Rust (Edition 2021) using tokio for async I/O, reqwest with rustls for OCI registry operations, and clap for CLI parsing. The architecture separates the CLI binary from the core domain library, with abstractions like ContainerRuntime (Docker/Podman), ConfigLoader (extends chain resolution), and FeatureInstaller (OCI installation with dependency resolution). Performance optimizations include container environment probe caching and parallel feature installation.

Getting Started

Install via curl: curl -fsSL https://get2knowio.github.io/deacon/install.sh | bash. Run deacon up --workspace-folder . in any directory with a .devcontainer/devcontainer.json to start a development container. Use deacon exec -- <command> to run commands inside, and deacon doctor --json for system diagnostics.

Technologies

rustdevcontainersdockerclideveloper-toolsoci
GitHubDocumentationcontainers.dev Spec