[Unit]
Description=Battleship relay
Documentation=https://github.com/agrauf67/battleship
After=network-online.target
Wants=network-online.target

[Service]
# Anything else the relay should be told - a certificate, for one - lives in this file,
# so turning TLS on does not mean editing a unit that the installer owns.
EnvironmentFile=-/etc/battleship-relay/options
ExecStart=/usr/bin/python3 /opt/battleship-relay/relay.py --port 8642 --key-file /etc/battleship-relay/key $RELAY_EXTRA
User=battleship
Group=battleship
Restart=on-failure
RestartSec=5

# The relay reads its key once, writes nothing and needs no privileges: it opens one
# listening socket and copies bytes. Everything else is taken away from it. /etc stays
# readable under ProtectSystem=strict, which is all the key file needs.
NoNewPrivileges=true
PrivateTmp=true
PrivateDevices=true
ProtectSystem=strict
ProtectHome=true
ProtectKernelTunables=true
ProtectKernelModules=true
ProtectControlGroups=true
RestrictAddressFamilies=AF_INET AF_INET6
RestrictNamespaces=true
RestrictSUIDSGID=true
LockPersonality=true
MemoryDenyWriteExecute=true
SystemCallArchitectures=native
CapabilityBoundingSet=
AmbientCapabilities=

[Install]
WantedBy=multi-user.target