Indent or sequencing problems with python - python-2.7

Question

I am new to python and have probably started with something a little complicated. Nevertheless I am nearly there.
My problem is I am having a bit of difficulty understanding how to group, or sequence a group of statements in my code (my syntax is probably wrong as well) using try and except or if, elsif and else. I really just need someone to say I should be using this instead of that and I can figure it out from there.
Here is a diagram of what I am trying to accomplish:
https://drive.google.com/file/d/0BxtxgkV8mylgSFRuMnZtaEpXLVE/view?usp=sharing
And here is my code so far (please note this is my FIRST python program - actually first program of any sort - so I would appreciate it if you would not tear me apart too badly for any formatting or syntax errors - updated to include Johns fix)
import ldap
import os
import subprocess
import uuid
from pwd import getpwnam
# Lookup all the users in the cloud group
path='dc=saao'
l=ldap.open('ldap1.cape')
l.protocol_version = ldap.VERSION3
l.simple_bind('dc=cape')
a=l.search_s(path,ldap.SCOPE_SUBTREE,'cn=cloudcape')
# Add members to uids
uids=a[0][1]['memberUid']
# Check if a bindmount already exists or it not, that each cloud group user has the required directory i.e. /home/USER/cloud and /var/www/owncloud/data/USER/files
for uid in uids:
cloudfiledir="/var/www/owncloud/data/"+uid+"/files"
clouddir="/home/"+uid+"/cloud"
try:
subprocess.check_output(["mountpoint", cloudfiledir])
# If the output is all good, their bind mount is setup and mounted
break
except:
print uid+" has not logged into ownCloud yet - please ask them to do so and then try again"
break
# Now check if they have the required directories
try:
if os.path.isdir(cloudfiledir):
print "user "+ uid +" has a data directory in the owncloud data directory- this is good."
if os.path.isdir("/home/"+uid+"/cloud"):
print "user "+ uid +" has a cloud dir in their home directory - this is good."
else:
# They don't have a cloud directory, creating one
print uid+" does not have a cloud folder in their home directory, creating it"
if not os.path.exists("/home/"+uid+"/cloud"):
os.makedirs("/home/"+uid+"/cloud")
# Now set permissions ("+uid+":Domain Users) - os.chown(path, uid, gid)
os.chown("/home/"+uid+"/cloud", "+uid+", "Domain Users")
else:
break
# Now make sure the cloufilesdir is empty
if not os.listdir(cloudfiledir):
print "Empty"
break
except:
print "rename and recreate the folder"
os.rename(clouddir, clouddir + str(uuid.uuid4()))
os.makedirs(clouddir)
os.chown(clouddir, 33, 33)
print "Now let's bind mount the directories"
# Bind each users home dir to their cloud dir
# Eg: bindfs -M www-data --create-for-user=1168 --create-for-group=513 /home/simon/cloud /var/www/owncloud/data/simon/files
# Still figuring this bit out
for user in a[0][1]['memberUid']:
filt = "(uid=" + user + ")"
u=l.search_s(path, ldap.SCOPE_SUBTREE, filt, ['uidNumber'])
print "\t", user, "filter: ", filt, u, "or"
uid = u[0][1]['uidNumber'][0]
print "\t\t", user, filt, uid
command = 'bindfs -M www-data --create-for-user=' + uid + ' --create-for-group=513 ' + '/home/' + user + '/cloud' + ' /var/www/owncloud/data/' + user + '/files'
print "BINGO: ", command, "\n"
John's advice fixed my except syntax, not I need to try and understand why the program only runs for the first UID and not the rest of them (there are 5 in the ldap group at the moment, 2 of which I have manually mounted so I would expect 3 bind mounts to happen).
I would appreciate any guidance as I continue to try and figure this out by trial and error.
Thanks in advance.
Simon

Answer 1

So, much reading and asking some wise colleagues later, I much a much better understanding of how for loops work, what break does and how useful continue can be.
Here is my final piece of code:
#!/usr/bin/python
import ldap
import os
import subprocess
import uuid
from pwd import getpwnam
# Lookup all the users in the cloudcape group
path='dc=cape'
l=ldap.open('ldap1.cape')
l.protocol_version = ldap.VERSION3
l.simple_bind('dc=cape')
a=l.search_s(path,ldap.SCOPE_SUBTREE,'cn=cloudcape')
# Add members to uids
uids=a[0][1]['memberUid']
# Check if a bindmount already exists or it not, that each cloud group user has the required directory i.e.home/USER/cloud and /var/www/owncloud/data/USER/files
for uid in uids:
# Define the directory paths
cloudfiledir="/var/www/owncloud/data/"+uid+"/files"
clouddir="/home/"+uid+"/cloud"
try:
subprocess.check_output(["mountpoint", cloudfiledir])
# If the output is all good, their bind mount is setup and mounted, if not carry on
except subprocess.CalledProcessError:
print uid+" does not have a mountpoint"
else:
continue
# Check if they have /var/www/owncloud/data/UID
if not os.path.isdir(cloudfiledir):
print uid+" does not have a owncloud directory structure in /var/www/owncloud, creating it"
os.makedirs("/var/www/owncloud/data/"+uid+"")
os.makedirs("/var/www/owncloud/data/"+uid+"/files")
os.makedirs("/var/www/owncloud/data/"+uid+"/cache")
# Now set permissions ("+uid+":Domain Users) - os.chown(path, uid, gid)
os.chown("/var/www/owncloud/data/"+uid+"", 33, 33)
os.chown("/var/www/owncloud/data/"+uid+"/files", 33, 33)
os.chown("/var/www/owncloud/data/"+uid+"/cache/", 33, 33)
# Now check if the have /home/UID/cloud
if not os.path.isdir(clouddir):
# They don't have a cloud directory, creating one
print uid+" does not have a cloud folder in their home directory, creating it"
os.makedirs(clouddir)
# Now set permissions ("+uid+":Domain Users) - os.chown(path, uid, gid)
os.chown(clouddir, "+uid+", "Domain Users")
# Now make sure the cloudfilesdir is empty
try:
if not os.listdir(cloudfiledir) == []:
print "The mount point is not empty"
os.rename(cloudfiledir, cloudfiledir + str(uuid.uuid4()))
os.makedirs(cloudfiledir)
os.chown(cloudfiledir, 33, 33)
except:
print "The mount point is empty, moving on"
print "Now let's bind mount the directories"
# Bind each users home dir to their cloud dir
filt = "(uid=" + uid + ")"
userid=l.search_s(path, ldap.SCOPE_SUBTREE, filt, ['uidNumber'])
print "\t", uid, "filter: ", filt, userid, "or"
numuid = userid[0][1]['uidNumber'][0]
print "\t\t", uid, filt, uid
os.system('bindfs -M www-data --create-for-user=' + numuid + ' --create-for-group=513 ' + '/home/' + uid + '/cloud' + ' /var/www/owncloud/data/' + uid + '/files')
I have no doubt there are simpler and more efficient ways to do this but for now, the code does what I want it to do. I still need to build some fault tolerance into it, I already spotted one area where it might fail if a certain directory exists but that is next weeks problem.