Prototype with single host server and no admin panel (#2)

Reviewed-on: wrenn/sandbox#2
Co-authored-by: pptx704 <rafeed@omukk.dev>
Co-committed-by: pptx704 <rafeed@omukk.dev>

images/wrenn-init.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+# wrenn-init: minimal PID 1 init for Firecracker microVMs.
+# Mounts virtual filesystems then execs envd.
+
+set -e
+
+# Mount essential virtual filesystems if not already mounted.
+mount -t proc proc /proc 2>/dev/null || true
+mount -t sysfs sysfs /sys 2>/dev/null || true
+mount -t devtmpfs devtmpfs /dev 2>/dev/null || true
+mkdir -p /dev/pts /dev/shm
+mount -t devpts devpts /dev/pts 2>/dev/null || true
+mount -t tmpfs tmpfs /dev/shm 2>/dev/null || true
+mount -t tmpfs tmpfs /tmp 2>/dev/null || true
+mount -t tmpfs tmpfs /run 2>/dev/null || true
+mkdir -p /sys/fs/cgroup
+mount -t cgroup2 cgroup2 /sys/fs/cgroup 2>/dev/null || true
+
+# Set hostname
+hostname sandbox
+
+# Configure DNS resolver.
+echo "nameserver 8.8.8.8" > /etc/resolv.conf
+echo "nameserver 8.8.4.4" >> /etc/resolv.conf
+
+# Set a standard PATH so envd and all child processes can find common binaries.
+export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+
+# Exec tini as PID 1 — it reaps zombie processes and forwards signals to envd.
+exec /sbin/tini -- /usr/local/bin/envd