nspawn: add new --network-veth-extra= switch for defining additional veth links

The new switch operates like --network-veth, but may be specified
multiple times (to define multiple link pairs) and allows flexible
definition of the interface names.

This is an independent reimplementation of #1678, but defines different
semantics, keeping the behaviour completely independent of
--network-veth. It also comes will full hook-up for .nspawn files, and
the matching documentation.

2 files changed, 32 insertions, 0 deletions

diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index 4725604c03..a97b7c44eb 100644
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -433,6 +433,21 @@
       </varlistentry>
 
       <varlistentry>
+        <term><option>--network-veth-extra=</option></term>
+
+        <listitem><para>Adds an additional virtual Ethernet link
+        between host and container. Takes a colon-separated pair of
+        host interface name and container interface name. The latter
+        may be omitted in which case the container and host sides will
+        be assigned the same name. This switch is independent of
+        <option>--network-veth</option>, and -- in contrast -- may be
+        used multiple times, and allows configuration of the network
+        interface names. Note that <option>--network-bridge=</option>
+        has no effect on interfaces created with
+        <option>--network-veth-extra=</option>.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>--network-bridge=</option></term>
 
         <listitem><para>Adds the host side of the Ethernet link
diff --git a/man/systemd.nspawn.xml b/man/systemd.nspawn.xml
index c2b7a40ec1..e952688331 100644
--- a/man/systemd.nspawn.xml
+++ b/man/systemd.nspawn.xml
@@ -324,6 +324,23 @@
       </varlistentry>
 
       <varlistentry>
+        <term><varname>VirtualEthernetExtra=</varname></term>
+
+        <listitem><para>Takes a colon-separated pair of interface
+        names. Configures an additional virtual Ethernet connection
+        (<literal>veth</literal>) between host and the container. The
+        first specified name is the interface name on the host, the
+        second the interface name in the container. The latter may be
+        omitted in which case it is set to the same name as the host
+        side interface. This setting implies
+        <varname>Private=yes</varname>. This setting corresponds to
+        the <option>--network-veth-extra=</option> command line
+        switch, and maybe be used multiple times. It is independent of
+        <varname>VirtualEthernet=</varname>. This option is privileged
+        (see above).</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><varname>Interface=</varname></term>
 
         <listitem><para>Takes a space-separated list of interfaces to