Virtualization - boat

You can run virtual machines inside a sandbox: QEMU/KVM, Firecracker, or the Android emulator at full speed.

Where your sandbox runs

	Standard machines	Fallback machines
Hardware	Dedicated AMD Ryzen 9 9950X (Zen 5) hosts	Hetzner cloud VMs with an older AMD CPU
When Boat uses them	Normally	When the standard machines are temporarily out of capacity. Boat uses them instead of a queue.
`/dev/kvm`	Yes. The CPU virtualization extensions are passed through.	No
Price	Same	Same
CPU-heavy work	Normal speed	Slower, about 3x on our build benchmark

Internally, we call the standard machines “baremetal”. Your sandbox is still a full virtual machine with its own kernel. It is not a bare-metal server. If you need KVM and /dev/kvm is missing, create a new sandbox a bit later.

Check for KVM

Do this check before you rely on KVM:

ls /dev/kvm && echo "KVM available"

Run the Android emulator

This script runs a headless Android emulator. We tested it on a large sandbox.

The install takes about one minute.
Android 14 then boots in 20 to 30 seconds.
The emulator needs about 3 GB of RAM. Use default or bigger.

sudo apt-get install -y openjdk-17-jre-headless
export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64 ANDROID_HOME=$HOME/android
mkdir -p $ANDROID_HOME/cmdline-tools && cd /tmp
curl -fsSLo clt.zip https://dl.google.com/android/repository/commandlinetools-linux-11076708_latest.zip
unzip -q clt.zip -d $ANDROID_HOME/cmdline-tools && mv $ANDROID_HOME/cmdline-tools/cmdline-tools $ANDROID_HOME/cmdline-tools/latest
SDK=$ANDROID_HOME/cmdline-tools/latest/bin
yes | $SDK/sdkmanager --licenses >/dev/null
$SDK/sdkmanager "platform-tools" "emulator" "system-images;android-34;google_apis;x86_64"
echo no | $SDK/avdmanager create avd -n phone -k "system-images;android-34;google_apis;x86_64" -d pixel_6
if [ ! -e /dev/kvm ]; then
  echo "No KVM on this sandbox: the Android emulator cannot start here." >&2
else
  $ANDROID_HOME/emulator/emulator -avd phone -no-window -no-audio -gpu swiftshader_indirect &
  $ANDROID_HOME/platform-tools/adb wait-for-device
fi

To take a screenshot, run adb exec-out screencap -p > screen.png.