Implement EBS volume mounting

This can either be invoked by instrumenting the user-data with a mime
part with content-type 'text/x-ebs-mount-description' with a body like
so:

device=/dev/sde:/var/lib/mysql,/etc/alfresco
device=/dev/sdf:/other/things

or by using the appliance config XML format like so:

<appliance>
  <storage device="/dev/sde">
	<path>/var/lib/mysql</path>
    <path>/etc/alfresco</path>
	</storage>
  <storage device="/dev/sdf">
    <path>/other/things</path>
  </appliance>
</appliance>

In either case, if the volume does not yet have a filesystem, one will be created.

For each path that is to live on the volume, a directory is created, and
populated with the data currently in the target directory (e.g.
/var/lib/mysql is copied to ${ebs_volume_path}/_var_lib_mysql). Once
this is done, the directories are bind-mounted to the relevant paths.
If the directories in question already exist, they will just be bind-mounted.

1 files changed, 22 insertions, 1 deletions

diff --git a/ec2-run-user-data.py b/ec2-run-user-data.py
index 67ecf219..d7e8e632 100755
--- a/ec2-run-user-data.py
+++ b/ec2-run-user-data.py
@@ -61,7 +61,7 @@ def handle_appliance_config(payload):
 
 @handler('text/x-ebs-mount-description')
 def handle_ebs_mount_description(payload):
-    (volume_description, path) = payload.split(':')
+    (volume_description, paths) = payload.split(':')
     (identifier_type, identifier) = volume_description.split('=')
 
     if identifier_type == 'device':
@@ -73,6 +73,17 @@ def handle_ebs_mount_description(payload):
     else:
         return
 
+    mount_ebs_volume(device, paths.split(','))
+
+def mount_ebs_volume(device, paths):
+    if os.path.exists('ec2-init-appliance-ebs-volume-mount.sh'):
+        helper = './ec2-init-appliance-ebs-volume-mount.sh'
+    else:
+        helper = '/usr/share/ec2-init/ec2-init-appliance-ebs-volume-mount.sh'
+    helper = subprocess.Popen([helper, device] + paths, stdout=subprocess.PIPE)
+    stdout, stderr = helper.communicate()
+    return stdout
+
 @handler('text/x-shellscript')
 def handle_shell_script(payload):
     (fd, path) = tempfile.mkstemp()
@@ -129,6 +140,16 @@ class ApplianceConfig(object):
                     # An empty script?
                     continue
                 content_type_handlers['text/x-shellscript'](script)
+            elif node.tagName == 'storage':
+                paths = []
+                device = node.getAttribute('device')
+                for subnode in node.childNodes:
+                    if subnode.tagName == 'path':
+                        for subsubnode in subnode.childNodes:
+                            if subsubnode.nodeType == root.TEXT_NODE:
+                                paths += [subsubnode.nodeValue.strip()]
+                                break
+                mount_ebs_volume(device, paths)
 
 def main():
     ec2 = ec2init.EC2Init()