Build and first boot

git clone https://github.com/bmalum/elixir_unikernel.git
cd elixir_unikernel
make check          # host prerequisites
make initramfs      # ~6 min cold, ~1 min when OTP/Elixir layers are cached
make run-m1         # build the Asterinas kernel (~4 min cold) and boot into IEx

make initramfs builds four Docker stages: an x86-64 Alpine sysroot, a cross-compiled OTP tree, a native OTP (so Elixir and Mix run at full speed), and the release. The output is build/initramfs.cpio.gz.

make run-m1 compiles Asterinas inside its upstream development container, applies the two patches from builder/asterinas-patches/, and starts QEMU:

Booting from ROM..OSTD initialized. Preparing components.
...
[kernel] unpacking initramfs.cpio.gz to rootfs ...
[kernel] running /init as the init process
[init] elixir_unikernel init, uptime 0.450 s
[init] net: eth0 10.0.2.15/24 gw 10.0.2.2
[init] exec /rel/erts-17.1/bin/beam.smp (iex mode)
Erlang/OTP 29 [erts-17.1] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:1] [jit:ns]
Interactive Elixir (1.20.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

Type an expression:

iex(1)> :inet.getifaddrs()
iex(2)> :ssl.connect(~c"www.erlang.org", 443, [verify: :verify_peer, cacertfile: ~c"/etc/ssl/cacert.pem"])

Leave QEMU with Ctrl-a followed by x.

The [init] lines about Not a tty on Asterinas are expected: that kernel does not implement the interface-configuration ioctls and configures 10.0.2.15/24 itself. /init logs and continues. See Networking.

Application mode

make run-m1-app

boots the same image with uniapp.mode=app: no shell, the release’s application starts under its supervision tree, and the sample app prints a few self-test lines:

LISTEN udp 4001
LISTEN tcp 4000
LISTEN tls 4443
PROBE dns ok
PROBE tls ok
PROBE done

While it runs, talk to it from another terminal:

printf 'hello\n' | nc 127.0.0.1 14000                                   # TCP echo
printf 'ping' | nc -u -w1 127.0.0.1 14001                               # UDP echo
(echo tls-hello; sleep 1) | openssl s_client -connect 127.0.0.1:14443 -tls1_3 -quiet

QEMU forwards host ports 14000, 14001 and 14443 to the guest’s 4000, 4001 and 4443.

The same image on Linux

make run-m0

boots build/initramfs.cpio.gz on a stock Linux 6.1 kernel (the Firecracker CI build, which has virtio and the serial console compiled in). Nothing in the image is Linux specific; this target exists so that a failure can be blamed on the right side of the syscall boundary.