nspawn,machined: change default container image location from /var/lib/container to /var/lib/machines

Given that this is also the place to store raw disk images which are
very much bootable with qemu/kvm it sounds like a misnomer to call the
directory "container". Hence, let's change this sooner rather than
later, and use the generic name, in particular since we otherwise try to
use the generic "machine" preferably over the more specific "container"
or "vm".

5 files changed, 64 insertions, 16 deletions

diff --git a/man/machinectl.xml b/man/machinectl.xml
index 91bdb5e111..19531866c7 100644
--- a/man/machinectl.xml
+++ b/man/machinectl.xml
@@ -291,10 +291,10 @@
                                 name. <command>systemd-nspawn</command>
                                 looks for a container image by the
                                 specified name in
-                                <filename>/var/lib/container</filename>
-                                and runs it. Use
-                                <command>list-images</command> (see
-                                below), for listing available
+                                <filename>/var/lib/machines/</filename>
+                                (and other search paths, see below) and runs
+                                it. Use <command>list-images</command>
+                                (see below), for listing available
                                 container images to start.</para>
 
                                 <para>Note that
@@ -488,7 +488,7 @@
                                 images. This enumerates all raw disk
                                 images and container directories and
                                 subvolumes in
-                                <filename>/var/lib/container/</filename>. Use
+                                <filename>/var/lib/machines/</filename> (and other search paths, see below). Use
                                 <command>start</command> (see above)
                                 to run a container off one of the
                                 listed images. Note that by default
@@ -596,6 +596,51 @@
         </refsect1>
 
         <refsect1>
+                <title>Files and Directories</title>
+
+                <para>Machine images are preferably stored in
+                <filename>/var/lib/machines/</filename>, but are also
+                searched for in
+                <filename>/usr/local/lib/machines/</filename> and
+                <filename>/usr/lib/machines/</filename>. For
+                compatibility reasons the directory
+                <filename>/var/lib/container/</filename> is searched,
+                too. Note that images stored below
+                <filename>/usr</filename> are always considered
+                read-only. It is possible to symlink machines images
+                from other directories into
+                <filename>/var/lib/machines/</filename> to make them
+                available for control with
+                <command>machinectl</command>.</para>
+
+                <para>Disk images are understood in three formats:</para>
+
+                <itemizedlist>
+                        <listitem><para>A simple directory tree,
+                        containing the files and directories of the
+                        container to boot.</para></listitem>
+
+                        <listitem><para>A subvolume (on btrfs file
+                        systems), which are similar to the simple
+                        directories, described above. However, they
+                        have additional benefits, such as efficient
+                        cloning and quota reporting.</para></listitem>
+
+                        <listitem><para>"Raw" disk images, i.e. binary
+                        images of disks with a GPT or MBR partition
+                        table. Images of this type are regular
+                        files with the suffix
+                        <literal>.raw</literal>.</para></listitem>
+                </itemizedlist>
+
+                <para>See
+                <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                for more information on image formats, in particular
+                it's <option>--directory=</option> and
+                <option>--image=</option> options.</para>
+        </refsect1>
+
+        <refsect1>
                 <title>Exit status</title>
 
                 <para>On success, 0 is returned, a non-zero failure
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index e67aeecb1a..0c6fb00289 100644
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -171,7 +171,7 @@
                                 <option>--directory=</option>, nor
                                 <option>--image=</option> is specified
                                 the directory is determined as
-                                <filename>/var/lib/container/</filename>
+                                <filename>/var/lib/machines/</filename>
                                 suffixed by the machine name as
                                 specified with
                                 <option>--machine=</option>. If
@@ -247,10 +247,13 @@
                                 the root directory for the container
                                 from. Takes a path to a regular file
                                 or to a block device node. The file or
-                                block device must contain a GUID
-                                Partition Table with a root partition
-                                which is mounted as the root directory
-                                of the container. Optionally, it may
+                                block device must contain either an
+                                MBR partition table with a single
+                                partition of type 0x83 that is marked
+                                bootable, or a GUID partition table
+                                with a root partition which is mounted
+                                as the root directory of the
+                                container. Optionally, GPT images may
                                 contain a home and/or a server data
                                 partition which are mounted to the
                                 appropriate places in the
@@ -842,7 +845,7 @@
                 <example>
                         <title>Enable Arch Linux container on boot</title>
 
-                        <programlisting># mv ~/arch-tree /var/lib/container/arch
+                        <programlisting># mv ~/arch-tree /var/lib/machines/arch
 # systemctl enable systemd-nspawn@arch.service
 # systemctl start systemd-nspawn@arch.service</programlisting>
 
diff --git a/src/import/import.c b/src/import/import.c
index 669d7c152c..b4d859df1f 100644
--- a/src/import/import.c
+++ b/src/import/import.c
@@ -29,7 +29,7 @@
 #include "import-dkr.h"
 
 static bool arg_force = false;
-static const char *arg_image_root = "/var/lib/container";
+static const char *arg_image_root = "/var/lib/machines";
 
 static const char* arg_dkr_index_url = DEFAULT_DKR_INDEX_URL;
 
diff --git a/src/shared/machine-image.c b/src/shared/machine-image.c
index a2f49e6e93..5112d24a8f 100644
--- a/src/shared/machine-image.c
+++ b/src/shared/machine-image.c
@@ -110,7 +110,7 @@ static int image_make(
         assert(filename);
 
         /* We explicitly *do* follow symlinks here, since we want to
-         * allow symlinking trees into /var/lib/container/, and treat
+         * allow symlinking trees into /var/lib/machines/, and treat
          * them normally. */
 
         if (fstatat(dfd, filename, &st, 0) < 0)
@@ -486,13 +486,13 @@ int image_clone(Image *i, const char *new_name, bool read_only) {
 
         case IMAGE_SUBVOLUME:
         case IMAGE_DIRECTORY:
-                new_path = strappenda("/var/lib/container/", new_name);
+                new_path = strappenda("/var/lib/machines/", new_name);
 
                 r = btrfs_subvol_snapshot(i->path, new_path, read_only, true);
                 break;
 
         case IMAGE_RAW:
-                new_path = strappenda("/var/lib/container/", new_name, ".raw");
+                new_path = strappenda("/var/lib/machines/", new_name, ".raw");
 
                 r = copy_file_atomic(i->path, new_path, read_only ? 0444 : 0644, false, FS_NOCOW_FL);
                 break;
diff --git a/tmpfiles.d/var.conf b/tmpfiles.d/var.conf
index d0c759e0fc..9b7644476b 100644
--- a/tmpfiles.d/var.conf
+++ b/tmpfiles.d/var.conf
@@ -18,6 +18,6 @@ f /var/log/btmp 0600 root utmp -
 d /var/cache 0755 - - -
 
 d /var/lib 0755 - - -
-v /var/lib/container 0700 - - -
+v /var/lib/machines 0700 - - -
 
 d /var/spool 0755 - - -