[Unit]
Description=digd.js - A lightweight DNS server in node.js.
Documentation=https://git.coolaj86.com/coolaj86/digd.js
After=network-online.target
Wants=network-online.target systemd-networkd-wait-online.service

[Service]
# Restart on crash (bad signal), but not on 'clean' failure (error exit code)
# Allow up to 3 restarts within 10 seconds
# (it's unlikely that a user or properly-running script will do this)
Restart=on-abnormal
StartLimitInterval=10
StartLimitBurst=3

# User and group the process will run as
# (git is the de facto standard on most systems)
User=digd
Group=digd

WorkingDirectory=/opt/digd.js
# TODO use --config instead of commandline params
ExecStart=/opt/digd.js/bin/node /opt/digd.js/bin/digd.js --port 53 --input /srv/digd.js/db.json +norecurse
ExecReload=/bin/kill -USR1 $MAINPID

# Limit the number of file descriptors and processes; see `man systemd.exec` for more limit settings.
# Unmodified digd.js is not expected to use more than this.
LimitNOFILE=1048576
LimitNPROC=64

# Use private /tmp and /var/tmp, which are discarded after digd.js stops.
PrivateTmp=true
# Use a minimal /dev
PrivateDevices=true
# Hide /home, /root, and /run/user. Nobody will steal your SSH-keys.
ProtectHome=true
# Make /usr, /boot, /etc and possibly some more folders read-only.
ProtectSystem=full
# ... except /srv/digd.js because we want a place for the database
# and /var/log/digd.js because we want a place where logs can go.
# This merely retains r/w access rights, it does not add any new.
# Must still be writable on the host!
ReadWriteDirectories=/opt/digd.js /srv/digd.js /var/log/digd.js

# Note: in v231 and above ReadWritePaths has been renamed to ReadWriteDirectories
; ReadWritePaths=/opt/digd.js /srv/digd.js /var/log/digd.js

# The following additional security directives only work with systemd v229 or later.
# They further retrict privileges that can be gained by digd.js.
# Note that you may have to add capabilities required by any plugins in use.
CapabilityBoundingSet=CAP_NET_BIND_SERVICE
AmbientCapabilities=CAP_NET_BIND_SERVICE
NoNewPrivileges=true

# Caveat: Some features may need additional capabilities.
# For example an "upload" may need CAP_LEASE
; CapabilityBoundingSet=CAP_NET_BIND_SERVICE CAP_LEASE
; AmbientCapabilities=CAP_NET_BIND_SERVICE CAP_LEASE
; NoNewPrivileges=true

[Install]
WantedBy=multi-user.target