generate-systemd-service-files

#!/bin/sh

SYSTEMD_VER=$(systemctl --version | head -1 | cut -d' ' -f2)

if [ ${SYSTEMD_VER} -lt 237 ]
then
    SYSTEMD_EXTRA=""
else
    SYSTEMD_EXTRA=$(cat <<EOF

RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
#MemoryDenyWriteExecute=true
ProtectKernelModules=true
ProtectKernelTunables=true
ProtectControlGroups=true
RestrictRealtime=true
RestrictNamespaces=true
EOF
                 )
fi

for BINARY in keydb-server keydb-sentinel
do
	for MODE in default templated
	do
		case "${BINARY}" in
		keydb-server)
			NAME="keydb"
			;;
		keydb-sentinel)
			NAME="sentinel"
			;;
		esac

		case "${MODE}" in
		default)
			EXTRA="Alias=${NAME}.service"
			TARGET="debian/${BINARY}.service"
			NAMESPACED="${NAME}"
			DESCRIPTION="Advanced key-value store"
			;;
		templated)
			EXTRA=""
			TARGET="debian/${BINARY}@.service"
			NAMESPACED="${NAME}-%i"
			DESCRIPTION="Advanced key-value store (%I)"
			;;
		esac

		: >${TARGET}

		if [ "${MODE}" = "templated" ]
		then
			cat >> ${TARGET} <<EOF
# Templated service file for ${BINARY}(1)
#
# Each instance of ${BINARY} requires its own configuration file:
#
#   $ cp /etc/keydb/${NAME}.conf /etc/keydb/${NAME}-myname.conf
#   $ chown keydb:keydb /etc/keydb/${NAME}-myname.conf
#
# Ensure each instance is using their own database:
#
#   $ sed -i -e 's@^dbfilename .*@dbfilename dump-myname.rdb@' /etc/keydb/${NAME}-myname.conf
#
# We then listen exlusively on UNIX sockets to avoid TCP port collisions:
#
#   $ sed -i -e 's@^port .*@port 0@' /etc/keydb/${NAME}-myname.conf
#   $ sed -i -e 's@^\\(# \\)\\{0,1\\}unixsocket .*@unixsocket /var/run/${NAME}-myname/${BINARY}.sock@' /etc/keydb/${NAME}-myname.conf
#
# ... and ensure we are logging, etc. in a unique location:
#
#   $ sed -i -e 's@^logfile .*@logfile /var/log/keydb/${BINARY}-myname.log@' /etc/keydb/${NAME}-myname.conf
#   $ sed -i -e 's@^pidfile .*@pidfile /var/run/keydb-myname/${BINARY}.pid@' /etc/keydb/${NAME}-myname.conf
#
# We can then start the service as follows, validating we are using our own
# configuration:
#
#   $ systemctl start ${BINARY}@myname.service
#   $ keydb-cli -s /var/run/${NAME}-myname/${BINARY}.sock info | grep config_file
#
#  -- Chris Lamb <lamby@debian.org>  Mon, 09 Oct 2017 22:17:24 +0100
EOF
		fi

		cat >> ${TARGET} <<EOF
[Unit]
Description=${DESCRIPTION}
After=network.target
Documentation=https://docs.keydb.dev, man:${BINARY}(1)

[Service]
Type=notify
ExecStart=/usr/bin/${BINARY} /etc/keydb/${NAMESPACED}.conf
ExecStop=/bin/kill -s TERM \$MAINPID
PIDFile=/var/run/${NAMESPACED}/${BINARY}.pid
TimeoutStopSec=0
Restart=always
User=keydb
Group=keydb
RuntimeDirectory=${NAMESPACED}
RuntimeDirectoryMode=2755

UMask=007
PrivateTmp=yes
LimitNOFILE=65535
PrivateDevices=yes
ProtectHome=yes
ReadOnlyDirectories=/
ReadWriteDirectories=-/var/lib/keydb
ReadWriteDirectories=-/var/log/keydb
ReadWriteDirectories=-/var/run/${NAMESPACED}

NoNewPrivileges=true
CapabilityBoundingSet=CAP_SETGID CAP_SETUID CAP_SYS_RESOURCE${SYSTEMD_EXTRA}

# ${BINARY} can write to its own config file when in cluster mode so we
# permit writing there by default. If you are not using this feature, it is
# recommended that you replace the following lines with "ProtectSystem=full".
ProtectSystem=true
ReadWriteDirectories=-/etc/keydb

[Install]
WantedBy=multi-user.target
EOF
		if [ "${EXTRA}" != "" ]
		then
			echo "${EXTRA}" >> "${TARGET}"
		fi
	done
done