ext_storage: Add 'snapshot' and 'setinfo' actions

Extend supported actions with the 'snapshot' action, which is used
to snapshot an existing image. Also add 'setinfo' action as NOP.
Finally, refactor 'ReadEnv' function to return a dictionary instead of a
tuple.

diff --git a/xseg/tools/ext_scripts/vlmc_wrapper.py b/xseg/tools/ext_scripts/vlmc_wrapper.py
index a412d2f..24ef39b 100755 (executable)
--- a/xseg/tools/ext_scripts/vlmc_wrapper.py
+++ b/xseg/tools/ext_scripts/vlmc_wrapper.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# Copyright (C) 2012 Greek Research and Technology Network
+# Copyright (C) 2012-2013 Greek Research and Technology Network
 #
 # 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
@@ -44,35 +44,51 @@ from archipelago import vlmc as vlmc
 
 
 def ReadEnv():
-    """Read the enviromental variables
-    """
-
+    """Read the enviromental variables"""
     name = os.getenv("VOL_NAME")
     if name is None:
         sys.stderr.write('The environment variable VOL_NAME is missing.\n')
         return None
-    size = os.getenv("VOL_SIZE")
-    origin = os.getenv("EXTP_ORIGIN")
-    return (name, size, origin)
+
+    return {"name": name,
+            "size": os.getenv("VOL_SIZE"),
+            "origin": os.getenv("EXTP_ORIGIN"),
+            "snapshot_name": os.getenv("VOL_SNAPSHOT_NAME"),
+            }
 
 
 def create(env):
-    """Create a new vlmc Image
-    """
-    name, size, origin = env
+    """Create a new vlmc Image."""
+    name = env.get("name")
+    size = env.get("size")
+    origin = env.get("origin")
+
+    sys.stderr.write("Creating volume '%s' of size '%s' from '%s'\n"
+                     % (name, size, origin))
     vlmc.create(name=name, size=int(size), snap=origin)
     return 0
 
 
+def snapshot(env):
+    """Create a snapshot of an existing vlmc Image."""
+    name = env.get("name")
+    snapshot_name = env.get("snapshot_name")
+    sys.stderr.write("Creating snapshot '%s' from '%s'\n" %
+                     (snapshot_name, name))
+    vlmc.snapshot(name=name, snap_name=snapshot_name)
+    return 0
+
+
 def attach(env):
     """Map an existing vlmc Image to a block device
 
     This function maps an existing vlmc Image to a block device
     e.g. /dev/xsegbd{X} and returns the device path. If the mapping
     already exists, it returns the corresponding device path.
+
     """
 
-    name, _, _ = env
+    name = env.get("name")
 
     # Check if the mapping already exists
     d_id = vlmc.is_mapped(name)
@@ -93,8 +109,9 @@ def detach(env):
 
     This function unmaps an vlmc device from the Image it is mapped to.
     It is idempotent if the mapping doesn't exist at all.
+
     """
-    name, _, _ = env
+    name = env.get("name")
 
     #try:
     # Check if the mapping already exists
@@ -110,20 +127,20 @@ def detach(env):
 
 
 def grow(env):
-    """Grow an existing vlmc Image
-    """
-    name, size, _ = env
+    """Grow an existing vlmc Image"""
+    name = env.get("name")
+    size = env.get("size")
 
+    sys.stderr.write("Resizing '%s'. New size '%s'\n" % (name, size))
     vlmc.resize(name=name, size=int(size))
     return 0
 
 
 def remove(env):
-    """ Delete a vlmc Image
-    """
-
-    name, _, _ = env
+    """Delete a vlmc Image"""
+    name = env.get("name")
 
+    sys.stderr.write("Deleting '%s'\n" % name)
     vlmc.remove(name=name)
     return 0
 
@@ -132,6 +149,10 @@ def verify(env):
     return 0
 
 
+def setinfo(env):
+    return 0
+
+
 def main():
     env = ReadEnv()
     if env is None:
@@ -140,23 +161,26 @@ def main():
 
     loadrc(None)
 
-    try:
-        action = {
-            'attach': attach,
-            'create': create,
-            'detach': detach,
-            'grow': grow,
-            'remove': remove,
-            'verify': verify
-        }[os.path.basename(sys.argv[0])]
-    except:
-        sys.stderr.write("Op not supported\n")
-        return 1
+    actions = {
+        'create': create,
+        'snapshot': snapshot,
+        'attach': attach,
+        'detach': detach,
+        'grow': grow,
+        'remove': remove,
+        'verify': verify,
+        'setinfo': setinfo,
+    }
 
     try:
+        action_name = os.path.basename(sys.argv[0])
+        action = actions[action_name]
         return action(env)
+    except KeyError:
+        sys.stderr.write("Action '%s' not supported\n" % action_name)
+        return 1
     except Error as e:
-        sys.stderr.write(str(e) + '\n')
+        sys.stderr.write("Archipelago error: %s\n" % e)
         return 1
 
 if __name__ == "__main__":