Megalodon/deploy/install.sh

#!/bin/sh
# Installs (or upgrades) Megalodon as a systemd service.
#
#   curl -fsSL https://git.veillax.com/Veillax/megalodon/raw/branch/main/deploy/install.sh | sudo sh
#   sudo sh install.sh [--start] [--version v0.1.0] [--listen 127.0.0.1:8480] [--source]
#   sudo sh install.sh --uninstall [--purge]
#
# What it does:
#   1. downloads the release archive for this machine and checks its SHA-256 (or, with --source,
#      clones the repository and builds it with Go),
#   2. installs the binary to /usr/local/bin/megalodon,
#   3. creates a "megalodon" user, /etc/megalodon (settings) and /var/lib/megalodon (data),
#   4. writes /etc/megalodon/megalodon.env and the systemd service,
#   5. tells you what to do next: edit the env file, start the service, watch the log.
#
# Running it again upgrades the binary and keeps your settings; a service that is already running
# is restarted. Add --start to start it straight away instead of editing the env file first.
set -eu

REPO_URL=${MEGALODON_REPO_URL:-https://git.veillax.com/Veillax/megalodon}
API_URL=${MEGALODON_API_URL:-https://git.veillax.com/api/v1/repos/Veillax/megalodon}
BIN=/usr/local/bin/megalodon
CONF_DIR=/etc/megalodon
DATA_DIR=/var/lib/megalodon
ENV_FILE=$CONF_DIR/megalodon.env
CONF_FILE=$CONF_DIR/megalodon.json
UNIT=/etc/systemd/system/megalodon.service
USER_NAME=megalodon

VERSION=""
LISTEN="127.0.0.1:8480"
SOURCE=0
START=0
UNINSTALL=0
PURGE=0

say() { printf '%s\n' "$*"; }
die() { printf 'install.sh: %s\n' "$*" >&2; exit 1; }

while [ $# -gt 0 ]; do
	case $1 in
	--version) VERSION=${2:?--version needs a value}; shift ;;
	--listen) LISTEN=${2:?--listen needs a value}; shift ;;
	--source) SOURCE=1 ;;
	--start) START=1 ;;
	--uninstall) UNINSTALL=1 ;;
	--purge) PURGE=1 ;;
	-h|--help) sed -n '2,19p' "$0" | sed 's/^# \{0,1\}//'; exit 0 ;;
	*) die "unknown option $1" ;;
	esac
	shift
done

[ "$(id -u)" -eq 0 ] || die "run as root (sudo sh install.sh)"
[ "$(uname -s)" = Linux ] || die "this installer is for Linux; on Windows, download the .zip from the releases page"
command -v systemctl >/dev/null 2>&1 || HAVE_SYSTEMD=0
HAVE_SYSTEMD=${HAVE_SYSTEMD:-1}

if [ "$UNINSTALL" -eq 1 ]; then
	if [ "$HAVE_SYSTEMD" -eq 1 ]; then
		systemctl disable --now megalodon 2>/dev/null || true
		rm -f "$UNIT"
		systemctl daemon-reload
	fi
	rm -f "$BIN"
	if [ "$PURGE" -eq 1 ]; then
		rm -rf "$CONF_DIR" "$DATA_DIR"
		userdel "$USER_NAME" 2>/dev/null || true
		say "Megalodon removed, including its settings and data."
	else
		say "Megalodon removed. Settings ($CONF_DIR) and data ($DATA_DIR) were kept; add --purge to delete them."
	fi
	exit 0
fi

fetch() { # fetch URL DEST
	if command -v curl >/dev/null 2>&1; then curl -fsSL -o "$2" "$1"
	elif command -v wget >/dev/null 2>&1; then wget -qO "$2" "$1"
	else die "need curl or wget"; fi
}

TMP=$(mktemp -d)
trap 'rm -rf "$TMP"' EXIT

# ---- 1. get the binary ----
if [ "$SOURCE" -eq 1 ]; then
	command -v git >/dev/null 2>&1 || die "--source needs git"
	command -v go >/dev/null 2>&1 || die "--source needs Go (https://go.dev/dl/)"
	say "Cloning $REPO_URL ..."
	git clone --quiet ${VERSION:+--branch "$VERSION"} --depth 1 "$REPO_URL" "$TMP/src"
	(cd "$TMP/src" && CGO_ENABLED=0 go build -trimpath -ldflags "-s -w -X main.version=${VERSION:-source}" -o "$TMP/megalodon" ./cmd/megalodon)
else
	case $(uname -m) in
	x86_64|amd64) ARCH=amd64 ;;
	aarch64|arm64) ARCH=arm64 ;;
	*) die "no release build for $(uname -m); try --source" ;;
	esac
	if [ -z "$VERSION" ]; then
		fetch "$API_URL/releases/latest" "$TMP/latest.json"
		VERSION=$(sed -n 's/.*"tag_name"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' "$TMP/latest.json" | head -n 1)
		[ -n "$VERSION" ] || die "could not find the latest release; use --version or --source"
	fi
	ARCHIVE="megalodon_${VERSION}_linux_${ARCH}.tar.gz"
	say "Downloading Megalodon $VERSION ($ARCH) ..."
	fetch "$REPO_URL/releases/download/$VERSION/$ARCHIVE" "$TMP/$ARCHIVE"
	fetch "$REPO_URL/releases/download/$VERSION/SHA256SUMS" "$TMP/SHA256SUMS"
	want=$(grep " $ARCHIVE\$" "$TMP/SHA256SUMS" | cut -d' ' -f1)
	[ -n "$want" ] || die "$ARCHIVE is not listed in SHA256SUMS"
	got=$(sha256sum "$TMP/$ARCHIVE" | cut -d' ' -f1)
	[ "$want" = "$got" ] || die "checksum mismatch for $ARCHIVE; refusing to install"
	tar -xzf "$TMP/$ARCHIVE" -C "$TMP"
	cp "$TMP/megalodon_${VERSION}_linux_${ARCH}/megalodon" "$TMP/megalodon"
fi

# ---- 2. install it ----
UPGRADE=0
[ -x "$BIN" ] && UPGRADE=1
if [ "$UPGRADE" -eq 1 ] && [ "$HAVE_SYSTEMD" -eq 1 ]; then systemctl stop megalodon 2>/dev/null || true; fi
install -m 0755 "$TMP/megalodon" "$BIN"
say "Installed $("$BIN" version) to $BIN"

# ---- 3. user and folders ----
id "$USER_NAME" >/dev/null 2>&1 || useradd --system --home-dir "$DATA_DIR" --shell /usr/sbin/nologin "$USER_NAME" 2>/dev/null \
	|| adduser --system --home "$DATA_DIR" --shell /usr/sbin/nologin "$USER_NAME" 2>/dev/null \
	|| die "could not create the $USER_NAME user"
# The dashboard rewrites its settings file, so the service must own the folder that holds it.
mkdir -p "$CONF_DIR" "$DATA_DIR"
chown "$USER_NAME" "$CONF_DIR" "$DATA_DIR"
chmod 0750 "$CONF_DIR" "$DATA_DIR"

# ---- 4. settings and environment file ----
if [ ! -f "$CONF_FILE" ]; then
	printf '{\n  "listen": "%s",\n  "data_dir": "%s"\n}\n' "$LISTEN" "$DATA_DIR" > "$CONF_FILE"
	chown "$USER_NAME" "$CONF_FILE"
	chmod 0600 "$CONF_FILE"
fi
if [ ! -f "$ENV_FILE" ]; then
	cat > "$ENV_FILE" <<EOF
# Environment for the megalodon service. Restart it after editing:  systemctl restart megalodon

# Where the settings file is. The dashboard edits this file, so leave it where the service can write.
MEGALODON_CONFIG=$CONF_FILE

# The time zone used by scheduled jobs ("04:30" means 04:30 in this zone). Examples: Europe/London,
# America/New_York, UTC. Leave it commented to use the server's own zone.
#TZ=Europe/London
EOF
	chmod 0600 "$ENV_FILE" # systemd reads it as root, so the service user does not need access
	say "Created $ENV_FILE. Edit it before starting."
fi

# ---- 5. service ----
if [ "$HAVE_SYSTEMD" -eq 0 ]; then
	say "systemd was not found, so no service was installed. Run it yourself with:"
	say "  sudo -u $USER_NAME env \$(grep -v '^#' $ENV_FILE | xargs) $BIN serve -config $CONF_FILE"
	exit 0
fi

cat > "$UNIT" <<EOF
[Unit]
Description=Megalodon, ARK server management over RCON
After=network-online.target
Wants=network-online.target

[Service]
User=$USER_NAME
EnvironmentFile=$ENV_FILE
WorkingDirectory=$DATA_DIR
ExecStart=$BIN serve
Restart=on-failure
RestartSec=5

# Megalodon only needs the network and its own folders.
NoNewPrivileges=true
ProtectSystem=strict
ReadWritePaths=$CONF_DIR $DATA_DIR
ProtectHome=true
PrivateTmp=true
PrivateDevices=true
ProtectKernelTunables=true
ProtectControlGroups=true
RestrictSUIDSGID=true
RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX

[Install]
WantedBy=multi-user.target
EOF
systemctl daemon-reload
systemctl enable megalodon >/dev/null 2>&1

if [ "$START" -eq 1 ] || systemctl is-active --quiet megalodon; then
	systemctl restart megalodon
	sleep 3
	if systemctl is-active --quiet megalodon; then
		say "Megalodon is running."
	else
		say "Megalodon did not start. Look at:  journalctl -u megalodon -n 50"
		exit 1
	fi
fi

say "Installed $("$BIN" version)."
say "Next:"
say "  1. sudoedit $ENV_FILE        (the time zone for schedules; the settings file is $CONF_FILE)"
say "  2. systemctl start megalodon      (or run this again with --start)"
say "  3. journalctl -u megalodon -f     to watch it; a first install prints the admin password here, once"
say ""
say "The dashboard is at http://$LISTEN"
case $LISTEN in
127.*|localhost*|[::1]*) say "It only listens on this machine. To reach it elsewhere, put an HTTPS reverse proxy (or Hammerhead) in front of it." ;;
esac