Add ostree.write deployment extension

This is a simple deployment extension to write the results of a Baserock
build to an OSTree repo.

See ostree.write.help for more information.

The Baserock reference systems contain static device nodes, which are
not supported by OSTree, and are obsolete on Linux systems. To work
around this problem, I added a strip-device-nodes.configure extension.
The systems should still work the same as devtmpfs will create the
device nodes.

I've tested this by deploying minimal-system-x86_64 to an OSTree repo,
then checking it out into a temporary directory, creating a read-only
bind-mount of the temporary directory and chrooting then into it.

This is only going to be useful for containers systems and chroots for
the time being. We would need to make some quite major changes to the
Baserock reference systems to enable deployment to VMs or bare metal
using OSTree.

Change-Id: I8556139d118da759360cdc1ce998590b1f50b644

1 files changed, 29 insertions, 0 deletions

diff --git a/extensions/strip-device-nodes.configure.help b/extensions/strip-device-nodes.configure.help
new file mode 100644
index 00000000..43b79a77
--- /dev/null
+++ b/extensions/strip-device-nodes.configure.help
@@ -0,0 +1,29 @@
+# Copyright (C) 2015 Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, see <http://www.gnu.org/licenses/>.
+
+help: |
+    A Baserock configuration extension for removing static device nodes.
+
+    Parameters:
+
+        STRIP_DEVICE_NODES=<1|0>: whether to strip device nodes
+
+    This extension is a workaround for a flaw in the Baserock reference systems.
+    They still contain statically created device nodes, which is not useful any
+    more for Linux systems due to the existance of the 'devtmpfs' filesystem.
+    The 'devtmpfs' filesystem creates device nodes automatically at run time.
+
+    Static device nodes are deliberately not supported by the OSTree tool, so this
+    .configure extension is needed to use the Baserock reference systems with the
+    ostree.write deployment extension.