$ show canonical/lxd
LXD is a modern, secure system container and virtual machine manager developed by Canonical. It provides a REST API over a Unix socket and HTTPS, a command-line client (lxc), and an in-guest agent (lxd-agent). The architecture is a monolithic daemon with pluggable storage drivers (ZFS, Btrfs, LVM, Ceph, dir, and enterprise SAN), network drivers (bridge, OVN, macvlan, SR-IOV, physical), and device passthrough (GPU, USB, NIC, TPM, proxy). It supports clustering via dqlite/Raft for high availability, fine-grained authorization via OpenFGA, OIDC authentication, and ACME certificate provisioning. The codebase is written in Go with CGo for low-level Linux operations (namespaces, seccomp, AppArmor, cgroups) and includes extensive unit and integration tests. Key features include live migration, incremental backups, cloud-init integration, and a built-in metrics endpoint for Prometheus.
The LLM identified 8 files worth highlighting for reuse:
Provides a generic revert/rollback mechanism using a slice of undo functions. Used extensively throughout the codebase for atomic operations (storage, devices, migration). The pattern is self-contained and can be extracted into any Go project needing safe rollback on failure.
A set of Go types that wrap iproute2 commands (ip link, addr, route, neigh, etc.) and tc (qdisc, class) in an object-oriented manner. Each type has methods like Add(), Delete(), and Flush() that construct and execute the corresponding CLI commands. This abstraction is reusable for any project that needs to manage Linux networking programmatically without shelling out to raw commands.
Implements a task group that manages the lifecycle of background tasks (start, stop, reset). Tasks are functions that run on a schedule (e.g., every N seconds) and can be gracefully stopped. The group handles concurrent start/stop and provides a Reset method for reconfiguration. This is a reusable pattern for any Go service needing periodic background work.
Provides a WebSocket proxy that mirrors traffic between a WebSocket connection and an io.ReadWriteCloser. Used for operations like console access and migration. The implementation is clean, handles bidirectional copying with proper error propagation, and can be reused in any Go project needing WebSocket-to-stream bridging.
Defines a typed configuration schema system with keys, validators, and defaults. Supports nested keys, user.* keys, and custom validators. The schema is used for server, cluster, and instance configuration. This pattern is reusable for any Go application needing a validated, extensible configuration system.
Implements retry logic for database transactions with exponential backoff and jitter. Handles transient errors (e.g., database locked) by retrying up to a configurable number of times. The implementation is generic and can be reused with any database/sql driver in Go.
Provides HMAC-based trust verification with Argon2id key derivation. Used for token binding and secure header generation. The implementation is self-contained, uses constant-time comparison, and can be reused in any Go project needing secure HMAC with key stretching.
Implements an in-memory bidirectional pipe that implements net.Conn. Used to create WebSocket-like sessions between the daemon and agent over vsock. The implementation is clean, handles concurrent reads/writes, and can be reused for any Go project needing a simple in-memory connection pair.