Add support for local SSDs

Add a systemd service which, on boot, partitions local SSD and
installs Rustup and Cargo on it for NayDuck to use.  Since the disk is
quite a bit larger than what we need, use part of it for swap which
should help with Docker tests sometimes failing.

automation/setup-host.sh

@@ -36,7 +36,7 @@ set -x
 
 apt-get -y update
 apt-get -y upgrade
-apt-get -y install git python3-pip libpq-dev lld libclang-dev
+apt-get -y install fdisk git python3-pip libpq-dev lld libclang-dev
 
 grep -q ^nayduck: /etc/passwd ||
 	adduser --disabled-login --gecos NayDuck nayduck
@@ -89,8 +89,8 @@ else
 fi
 
 case $type in
-frontend) services=ui              ;;
-worker)   services='worker fuzzer' ;;
+frontend) services=ui                        ;;
+worker)   services='local-ssd worker fuzzer' ;;
 *)        services=$type
 esac
 for service in $services; do

systemd/nayduck-fuzzer.service

@@ -1,6 +1,6 @@
 [Unit]
 Description=NayDuck Fuzzer
-After=network.target
+After=network.target local-ssd.service
 
 [Service]
 Restart=always

systemd/nayduck-local-ssd.service

@@ -0,0 +1,8 @@
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+WorkingDirectory=/home/nayduck/nayduck
+ExecStart=/bin/sh systemd/setup-local-ssd.sh
+
+[Install]
+WantedBy=multi-user.target

systemd/nayduck-worker.service

@@ -1,6 +1,6 @@
 [Unit]
 Description=NayDuck Worker
-After=network.target nayduck-fuzzer.service
+After=network.target nayduck-fuzzer.service local-ssd.service
 
 [Service]
 Restart=always

systemd/setup-local-ssd.sh

@@ -0,0 +1,53 @@
+#!/bin/sh
+
+set -eux
+
+dev=/dev/nvme0n1
+dir=/datadrive
+
+# Sanity checks
+if ! [ -e "$dev" ]; then
+	echo "$dev: device does not exist; nothing to do"
+	exit 0
+fi
+
+if ! [ -e "${dev}p1" ]; then
+	# Partition the disk:
+	# - p1 → data partition, will become /datadrive
+	# - p2 → swap partition
+	sfdisk "$dev" <<EOF
+		size=360G
+		type=swap
+		write
+EOF
+
+	# Data on the device is essentially lost on reboot and we’re treating it as
+	# ephemeral.  There’s no point in keeping journal.
+	mkfs.ext4 -E discard -O ^has_journal "${dev}p1"
+	mkdir -p "$dir"
+	mount "${dev}p1" "$dir" -o discard,noatime,nobarrier
+	chown nayduck:nayduck "$dir"
+
+	cat >$dir/README <<EOF
+	Data in this directory is ephemeral and may disappear on reboots.
+	Don’t keep any data which cannot be recreated here.
+EOF
+	chmod 644 "$dir/README"
+
+	# Install Rustup and Cargo in /datadrive/home for NayDuck to use.  Those always
+	# take a lot of space so best keep them on our massive local SSD.
+	mkdir -p "$dir/home"
+	chown nayduck:nayduck "$dir/home"
+	sudo -u nayduck CARGO_HOME="$dir/home/cargo" RUSTUP_HOME="$dir/home/rustup" '
+		set -eux
+		curl https://sh.rustup.rs -sSf | sh -s -- -y
+		"$CARGO_HOME/bin/rustup" target add wasm32-unknown-unknown
+		"$CARGO_HOME/bin/cargo" install cargo-fuzz
+	'
+else
+	mount "${dev}p1" "$dir" -o discard,noatime,nobarrier
+fi
+
+# Enable swap on the second partition
+mkswap "${dev}p2"
+swapon "${dev}p2"

workers/utils.py

@@ -278,21 +278,28 @@ def int_to_ip(addr: int) -> str:
 
 def setup_environ() -> None:
     """Configures environment variables for workers and builders."""
+    # Look for Cargo.
+    path = WORKDIR / 'home/cargo'
+    if (path / 'bin/cargo').is_file():
+        os.environb[b'CARGO_HOME'] = os.fsencode(path)
+        os.environb[b'RUSTUP_HOME'] = os.fsencode(WORKDIR / 'home/rustup')
+        cargo_bin = path / 'bin'
+    else:
+        cargo_bin = pathlib.Path.home() / '.cargo/bin'
+
     # Add Cargo to PATH and remove various unnecessary directories
     pathsep = os.fsencode(os.pathsep)
     paths = os.environb.get(b'PATH', os.fsencode(os.defpath)).split(pathsep)
     paths = [
         path for path in paths
         if path.startswith(b'/') and not path.endswith(b'/sbin')
     ]
-
-    cargo_bin = pathlib.Path.home() / '.cargo/bin'
     if cargo_bin.exists():
         paths.insert(0, os.fsencode(cargo_bin))
-
     os.environb[b'PATH'] = pathsep.join(paths)
 
-    # Configure Cargo builds
+    # Configure Cargo builds to make compilation faster.  We don’t need
+    # super-optimised builds thus disabling LTO and using lld.
     os.environb[b'CARGO_PROFILE_RELEASE_LTO'] = b'false'
     os.environb[b'CARGO_PROFILE_DEV_DEBUG'] = b'0'
     os.environb[b'CARGO_PROFILE_TEST_DEBUG'] = b'0'