updated to work back to v229 and fixed conventions

etc/systemd/system/caddy.service

@@ -5,58 +5,59 @@ 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)
+# 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
-; Allow up to 3 restarts within 10 seconds
-; (it's unlikely that a user or properly-running script will do this)
 StartLimitInterval=10
 StartLimitBurst=3
 
-; User and group the process will run as
-; (www-data is the de facto standard on most systems)
+# User and group the process will run as
+# (www-data is the de facto standard on most systems)
 User=www-data
 Group=www-data
 
-; Letsencrypt-issued certificates will be written to this directory.
+# Letsencrypt-issued certificates will be written to this directory.
 Environment=CADDYPATH=/etc/ssl/caddy
 
-; Always set "-root" to something safe in case it gets forgotten in the Caddyfile.
+# Always set "-root" to something safe in case it gets forgotten in the Caddyfile.
 WorkingDirectory=/etc/ssl/caddy
 ExecStart=/usr/local/bin/caddy -log stdout -agree=true -conf=/etc/caddy/Caddyfile -root=/var/tmp
 ExecReload=/bin/kill -USR1 $MAINPID
 
-; Limit the number of file descriptors; see `man systemd.exec` for more limit settings.
+# Limit the number of file descriptors and processes; see `man systemd.exec` for more limit settings.
+# Unmodified caddy is not expected to use more than this.
 LimitNOFILE=1048576
-; Unmodified caddy is not expected to use more than that.
 LimitNPROC=64
 
-; Use private /tmp and /var/tmp, which are discarded after caddy stops.
+# Use private /tmp and /var/tmp, which are discarded after caddy stops.
 PrivateTmp=true
-; Use a minimal /dev
+# Use a minimal /dev
 PrivateDevices=true
-; Hide /home, /root, and /run/user. Nobody will steal your SSH-keys.
+# 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.
+# Make /usr, /boot, /etc and possibly some more folders read-only.
 ProtectSystem=full
-; … except /etc/ssl/caddy, because we want Letsencrypt-certificates there
-;   and /var/log/caddy, 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!
-ReadWritePaths=/etc/ssl/caddy /var/log/caddy
+# … except /etc/ssl/caddy, because we want Letsencrypt-certificates there
+#   and /var/log/caddy, 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=/etc/ssl/caddy /var/log/caddy
 
-; The following additional security directives only work with systemd v229 or later.
-; They further retrict privileges that can be gained by caddy. Uncomment if you like.
-; Note that you may have to add capabilities required by any plugins in use.
+# Note: in v231 and above ReadWritePaths has been renamed to ReadWriteDirectories
+; ReadWritePaths=/etc/ssl/caddy /var/log/caddy
+
+# The following additional security directives only work with systemd v229 or later.
+# They further retrict privileges that can be gained by caddy.
+# 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 plugins need additional capabilities. Add them to both lines above.
-; - plugin "upload" needs: CAP_LEASE
+# Caveat: Some plugins need additional capabilities.
+# For example "upload" needs CAP_LEASE
+; CapabilityBoundingSet=CAP_NET_BIND_SERVICE CAP_LEASE
+; AmbientCapabilities=CAP_NET_BIND_SERVICE CAP_LEASE
+; NoNewPrivileges=true
 
 [Install]
 WantedBy=multi-user.target
-
-; Learn more:
-;
-;   * systemd: https://www.freedesktop.org/software/systemd/man/systemd.exec.html
-;   * why caddy's systemd file is what it is https://github.com/mholt/caddy/pull/1566/files