Merge pull request #62 from marineam/units

add(units): Generic config drive and other systemd units.

Documentation/config-drive.md

@@ -0,0 +1,30 @@
+# Distribution via Config Drive
+
+CoreOS supports providing configuration data via [config drive][config-drive]
+disk images. Currently only providing a single script or cloud config file is
+supported.
+
+[config-drive]: http://docs.openstack.org/user-guide/content/enable_config_drive.html#config_drive_contents
+
+## Contents and Format
+
+The image should be a single FAT or ISO9660 file system with the label
+`config-2` and the configuration data should be located at
+`openstack/latest/user_data`.
+
+For example, to wrap up a config named `user_data` in a config drive image:
+
+    mkdir -p /tmp/new-drive/openstack/latest
+    cp user_data /tmp/new-drive/openstack/latest/user_data
+    mkisofs -R -V config-2 -o configdrive.iso /tmp/new-drive
+    rm -r /tmp/new-drive
+
+## QEMU virtfs
+
+One exception to the above, when using QEMU it is possible to skip creating an
+image and use a plain directory containing the same contents:
+
+    qemu-system-x86_64 \
+        -fsdev local,id=conf,security_model=none,readonly,path=/tmp/new-drive \
+        -device virtio-9p-pci,fsdev=conf,mount_tag=config-2 \
+        [usual qemu options here...]