# rusty-initramfs-builder
A Rust CLI tool to convert Docker/OCI images into bootable initramfs for microVMs.
## Installation
```bash
cargo install initramfs-builder
```
## Quick Start
```bash
# Build an initramfs from a Docker image
initramfs-builder build python:3.12-alpine -o python.cpio.gz
# Inject a custom binary and init script
initramfs-builder build python:3.12-alpine \
--inject ./my-agent:/usr/bin/my-agent \
--init ./init.sh \
-o python-lambda.cpio.gz
```
## Usage
```bash
# Build initramfs
initramfs-builder build <IMAGE> [OPTIONS]
Options:
-o, --output <FILE> Output file [default: initramfs.cpio.gz]
--inject <SRC:DEST> Inject file into initramfs (can be repeated)
--init <SCRIPT> Custom init script (placed at /init)
--exclude <PATTERN> Exclude files matching pattern
--platform-arch <ARCH> Target architecture [default: amd64]
-c, --compression <FMT> gzip, zstd, or none [default: gzip]
# Inspect image
initramfs-builder inspect <IMAGE>
# List layers
initramfs-builder list-layers <IMAGE>
```
## Example init script
```bash
#!/bin/sh
mount -t proc proc /proc
mount -t sysfs sysfs /sys
mount -t devtmpfs devtmpfs /dev
exec /usr/bin/my-agent
```
## Documentation
See [docs/](docs/) for detailed documentation:
- [Architecture](docs/architecture.md) - How it works internally
- [Integration](docs/integration.md) - Using with rust-vmm/Firecracker
## License
MIT