doc: add information about systemd support

README

@@ -13,6 +13,7 @@ Optional packages:
 * libcap-ng >= 0.6.4 (for POSIX 1003.1e capabilites(7))
 * libidn             (for IDNA2003 support in Knot utilities)
 * lmdb               (for persistent events for slave zones)
+* libsystemd         (for systemd init system support)
 
 Dependencies for building documentation:
 * python-sphinx
@@ -39,7 +40,7 @@ Install prerequisites:
 $ sudo apt-get install git-core libtool autoconf flex bison libssl-dev liburcu-dev
 
 Install optional packages:
-($ sudo apt-get install libcap-ng-dev liblmdb-dev)
+($ sudo apt-get install libcap-ng-dev liblmdb-dev libsystemd-dev)
 
 If the liburcu-dev package is not present, install it from the source code
 (http://lttng.org/urcu)
@@ -56,7 +57,7 @@ Ensure all prerequisites are installed:
 $ yum install libtool autoconf flex bison openssl-devel userspace-rcu-devel
 
 Install optional packages:
-($ yum install libcap-ng-devel lmdb-devel)
+($ yum install libcap-ng-devel lmdb-devel systemd-devel)
 
 2) Install Knot DNS
 

doc/installation.rst

@@ -37,6 +37,7 @@ Knot DNS requires few libraries to be compiled:
 * Userspace RCU, at least 0.5.4
 * libcap-ng, at least 0.6.4 (optional library)
 * lmdb (optional library)
+* libsystemd (optional library)
 
 If the libcap-ng library is available, Knot DNS will take advantage of the
 POSIX 1003.1e capabilites(7) by sandboxing the exposed threads.  Most
@@ -46,6 +47,9 @@ If the LMDB library is available, the server will be able to store timers
 for slave zones in file-backed storage and the timers will persist across
 server restarts.
 
+If the libsystemd library is available, the server will use systemd's startup
+notifications mechanism and journald for logging.
+
 You can probably find OpenSSL and zlib libraries already included in
 your system or distribution.  If not, zlib resides at http://zlib.net,
 and OpenSSL can be found at http://www.openssl.org.

doc/reference.rst

@@ -1094,7 +1094,7 @@ serious will be logged to both ``stderr`` and ``syslog``.  The
 
 * ``stdout`` - logging to standard output
 * ``stderr`` - logging to standard error output
-* ``syslog`` - logging to syslog
+* ``syslog`` - logging to syslog (or systemd journal, if systemd support is enabled)
 
 .. _category:
 
@@ -1107,6 +1107,10 @@ Knot DNS allows user to choose from these logging categories:
 * ``zone`` - Messages related to zones, zone parsing and loading.
 * ``any`` - All categories.
 
+If systemd support is enabled, the log messages in the `zone` category are
+given the `ZONE` field containing a name of the zone. The field can be used
+to filter the log entries in the journal.
+
 .. _severity:
 
 ``severity``