man: document journald namespaces

1 files changed, 50 insertions, 5 deletions

diff --git a/man/systemd-journald.service.xml b/man/systemd-journald.service.xml
index ec9f974f2d..f4ce4e4fe2 100644
--- a/man/systemd-journald.service.xml
+++ b/man/systemd-journald.service.xml
@@ -20,6 +20,9 @@
     <refname>systemd-journald.socket</refname>
     <refname>systemd-journald-dev-log.socket</refname>
     <refname>systemd-journald-audit.socket</refname>
+    <refname>systemd-journald@.service</refname>
+    <refname>systemd-journald@.socket</refname>
+    <refname>systemd-journald-varlink@.socket</refname>
     <refname>systemd-journald</refname>
     <refpurpose>Journal service</refpurpose>
   </refnamediv>
@@ -29,6 +32,9 @@
     <para><filename>systemd-journald.socket</filename></para>
     <para><filename>systemd-journald-dev-log.socket</filename></para>
     <para><filename>systemd-journald-audit.socket</filename></para>
+    <para><filename>systemd-journald@.service</filename></para>
+    <para><filename>systemd-journald@.socket</filename></para>
+    <para><filename>systemd-journald-varlink@.socket</filename></para>
     <para><filename>/usr/lib/systemd/systemd-journald</filename></para>
   </refsynopsisdiv>
 
@@ -130,6 +136,40 @@ systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
   </refsect1>
 
   <refsect1>
+    <title>Journal Namespaces</title>
+
+    <para>Journal 'namespaces' are both a mechanism for logically isolating the log stream of projects
+    consisting of one or more services from the rest of the system and a mechanism for improving
+    performance. Multiple journal namespaces may exist simultaneously, each defining its own, independent log
+    stream managed by its own instance of <command>systemd-journald</command>. Namespaces are independent of
+    each other, both in the data store and in the IPC interface. By default only a single 'default' namespace
+    exists, managed by <filename>systemd-journald.service</filename> (and its associated socket
+    units). Additional namespaces are created by starting an instance of the
+    <filename>systemd-journald@.service</filename> service template. The instance name is the namespace
+    identifier, which is a short string used for referencing the journal namespace. Service units may be
+    assigned to a specific journal namespace through the <varname>LogNamespace=</varname> unit file setting,
+    see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
+    details. The <option>--namespace=</option> switch of
+    <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> may be
+    used to view the log stream of a specific namespace. If the switch is not used the log stream of the
+    default namespace is shown, i.e. log data from other namespaces is not visible.</para>
+
+    <para>Services associated with a specific log namespace may log via syslog, the native logging protocol
+    of the journal and via stdout/stderr; the logging from all three transports is associated with the
+    namespace.</para>
+
+    <para>By default only the default namespace will collect kernel and audit log messages.</para>
+
+    <para>The <command>systemd-journald</command> instance of the default namespace is configured through
+    <filename>/etc/systemd/journald.conf</filename> (see below), while the other instances are configured
+    through <filename>/etc/systemd/journald@<replaceable>NAMESPACE</replaceable>.conf</filename>. The journal
+    log data for the default namespace is placed in
+    <filename>/var/log/journal/<replaceable>MACHINE_ID</replaceable></filename> (see below) while the data
+    for the other namespaces is located in
+    <filename>/var/log/journal/<replaceable>MACHINE_ID</replaceable>.<replaceable>NAMESPACE</replaceable></filename>.</para>
+  </refsect1>
+
+  <refsect1>
     <title>Signals</title>
 
     <variablelist>
@@ -190,6 +230,9 @@ systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
 
       </varlistentry>
     </variablelist>
+
+    <para>Note that these kernel command line options are only honoured by the default namespace, see
+    above.</para>
   </refsect1>
 
   <refsect1>
@@ -279,12 +322,14 @@ systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
         <term><filename>/run/systemd/journal/socket</filename></term>
         <term><filename>/run/systemd/journal/stdout</filename></term>
 
-        <listitem><para>Sockets and other paths that
-        <command>systemd-journald</command> will listen on that are
-        visible in the file system. In addition to these, journald can
-        listen for audit events using netlink.</para></listitem>
+        <listitem><para>Sockets and other file node paths that <command>systemd-journald</command> will
+        listen on and are visible in the file system. In addition to these,
+        <command>systemd-journald</command> can listen for audit events using <citerefentry
+        project='man-pages'><refentrytitle>netlink</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
       </varlistentry>
     </variablelist>
+
+    <para>If journal namespacing is used these paths are slightly altered to include a namespace identifier, see above.</para>
   </refsect1>
 
   <refsect1>
@@ -296,7 +341,7 @@ systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
       <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-      <citerefentry project='die-net'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
       <command>pydoc systemd.journal</command>
     </para>