nspawn: beef up nspawn with some btrfs magic
This adds --template= to duplicate an OS tree as btrfs snpashot and run it This also adds --ephemeral or -x to create a snapshot of an OS tree and boot that, removing it after exit.
This commit is contained in:
Lennart Poettering
+82
-16
@@ -165,14 +165,78 @@
|
||||
<term><option>--directory=</option></term>
|
||||
|
||||
<listitem><para>Directory to use as
|
||||
file system root for the container. If
|
||||
neither <option>--directory=</option>
|
||||
nor <option>--image=</option> are
|
||||
file system root for the container.</para>
|
||||
|
||||
<para>If neither
|
||||
<option>--directory=</option>, nor
|
||||
<option>--image=</option> is specified
|
||||
the directory is determined as
|
||||
<filename>/var/lib/container/</filename>
|
||||
suffixed by the machine name as
|
||||
specified with
|
||||
<option>--machine=</option>. If
|
||||
neither <option>--directory=</option>,
|
||||
<option>--image=</option>, nor
|
||||
<option>--machine=</option> are
|
||||
specified, the current directory will
|
||||
be used. May not be specified together with
|
||||
be used. May not be specified together
|
||||
with
|
||||
<option>--image=</option>.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><option>--template=</option></term>
|
||||
|
||||
<listitem><para>Directory or
|
||||
<literal>btrfs</literal> subvolume to
|
||||
use as template for the container's
|
||||
root directory. If this is specified
|
||||
and the container's root directory (as
|
||||
configured by
|
||||
<option>--directory=</option>) does
|
||||
not yet exist it is created as
|
||||
<literal>btrfs</literal> subvolume and
|
||||
populated from this template
|
||||
tree. Ideally, the specified template
|
||||
path refers to the root of a
|
||||
<literal>btrfs</literal> subvolume, in
|
||||
which case a simple copy-on-write
|
||||
snapshot is taken, and populating the
|
||||
root directory is instant. If the
|
||||
specified template path does not refer
|
||||
to the root of a
|
||||
<literal>btrfs</literal> subvolume (or
|
||||
not even to a <literal>btrfs</literal>
|
||||
file system at all), the tree is
|
||||
copied, which can be substantially
|
||||
more time-consuming. Note that if this
|
||||
option is used the container's root
|
||||
directory (in contrast to the template
|
||||
directory!) must be located on a
|
||||
<literal>btrfs</literal> file system,
|
||||
so that the <literal>btrfs</literal>
|
||||
subvolume may be created. May not be
|
||||
specified together with
|
||||
<option>--image=</option> or
|
||||
<option>--ephemeral</option>.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><option>-x</option></term>
|
||||
<term><option>--ephemeral</option></term>
|
||||
|
||||
<listitem><para>If specified, the
|
||||
container is run with a temporary
|
||||
<literal>btrfs</literal> snapshot of
|
||||
its root directory (as configured with
|
||||
<option>--directory=</option>), that
|
||||
is removed immediately when the
|
||||
container terminates. May not be
|
||||
specified together with
|
||||
<option>--image=</option> or
|
||||
<option>--template=</option>.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><option>-i</option></term>
|
||||
<term><option>--image=</option></term>
|
||||
@@ -197,7 +261,9 @@
|
||||
partitions, swap partitions or EFI
|
||||
system partitions are not mounted. May
|
||||
not be specified together with
|
||||
<option>--directory=</option>.</para></listitem>
|
||||
<option>--directory=</option>,
|
||||
<option>--template=</option> or
|
||||
<option>--ephemeral</option>.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
@@ -653,13 +719,13 @@
|
||||
<term><option>--volatile</option><replaceable>=MODE</replaceable></term>
|
||||
|
||||
<listitem><para>Boots the container in
|
||||
volatile (ephemeral) mode. When no
|
||||
mode parameter is passed or when mode
|
||||
is specified as <literal>yes</literal>
|
||||
full volatile mode is enabled. This
|
||||
means the root directory is mounted as
|
||||
mostly unpopulated
|
||||
<literal>tmpfs</literal> instance, and
|
||||
volatile mode. When no mode parameter
|
||||
is passed or when mode is specified as
|
||||
<literal>yes</literal> full volatile
|
||||
mode is enabled. This means the root
|
||||
directory is mounted as mostly
|
||||
unpopulated <literal>tmpfs</literal>
|
||||
instance, and
|
||||
<filename>/usr</filename> from the OS
|
||||
tree is mounted into it, read-only
|
||||
(the system thus starts up with
|
||||
@@ -677,8 +743,8 @@
|
||||
changes to the latter are lost on
|
||||
shutdown). When the mode parameter is
|
||||
specified as <literal>no</literal>
|
||||
(the default) the whole OS tree is made
|
||||
available writable.</para>
|
||||
(the default) the whole OS tree is
|
||||
made available writable.</para>
|
||||
|
||||
<para>Note that setting this to
|
||||
<literal>yes</literal> or
|
||||
@@ -748,13 +814,13 @@
|
||||
</example>
|
||||
|
||||
<example>
|
||||
<title>Boot into a btrfs snapshot of the host system</title>
|
||||
<title>Boot into a <literal>btrfs</literal> snapshot of the host system</title>
|
||||
|
||||
<programlisting># btrfs subvolume snapshot / /.tmp
|
||||
# systemd-nspawn --private-network -D /.tmp -b</programlisting>
|
||||
|
||||
<para>This runs a copy of the host system in a
|
||||
btrfs snapshot.</para>
|
||||
<literal>btrfs</literal> snapshot.</para>
|
||||
</example>
|
||||
|
||||
<example>
|
||||
|
||||
Reference in New Issue
Block a user