wacon

Minimal container runtime with RISC-V emulator, written in MoonBit.

Demo: mizchi.github.io/wacon

Alpine Linux の busybox (static-pie, RV64) をブラウザ上の RISC-V エミュレータで実行する。

What works

$ echo hello from wacon    → hello from wacon     (35ms)
$ cat /etc/hostname         → wacon                (19ms)
$ cat /etc/os-release       → Alpine Linux v3.21   (14ms)

Architecture

Browser (JS)
  ↓ fetch busybox.elf (1MB, Alpine riscv64 static-pie)
  ↓ MoonBit JS (225KB, gzip 23KB)
  ↓
┌─────────────────────────────────┐
│  RV64IMACFD Emulator            │
│  ├── RV64I base (LD/SD/ADDIW)  │
│  ├── M ext (MUL/DIV/REM)       │
│  ├── A ext (LR/SC/AMO)         │
│  ├── C ext (compressed 16-bit) │
│  ├── F/D ext (floating point)  │
│  ├── ELF64 loader (PIE+RELA)   │
│  └── Linux syscall shim (30+)  │
├─────────────────────────────────┤
│  Virtual Filesystem (VFS)       │
│  ├── /bin (busybox symlinks)    │
│  ├── /etc (passwd, hostname)    │
│  ├── /proc/self/exe            │
│  └── /dev (null, zero, tty)    │
├─────────────────────────────────┤
│  OCI Container Runtime          │
│  ├── Registry client (Docker Hub)│
│  ├── Manifest/blob store        │
│  ├── gzip decompression (zlib)  │
│  └── WASM VM (separate)        │
└─────────────────────────────────┘

Stats

• 5,767 lines of MoonBit
• 51 tests passing
• 13 commits from zero to browser demo
• Emulator: 225KB JS (23KB gzip)
• busybox: 998KB ELF (Alpine riscv64 static-pie)

Packages

Package	Description
rv64	RV64IMACFD emulator (exec, alu, rvc, fpu, atomic, elf, syscall, mem)
rv32i	RV32I emulator (original prototype)
vfs	In-memory virtual filesystem
wasm	WASM binary parser + stack VM + WASI shim
oci	OCI manifest/descriptor parser
registry	OCI Distribution API client
store	Content-addressable blob store
types	Shared OCI types

Build

just           # check + test (native)
just run       # run CLI

# Browser build
moon build --target js --release src/cmd/wasm

License

Apache-2.0