How-To: Check and Fix if Notifier Files are Corrupted

How to check and fix if notifier files are corrupted

Note: Before proceeding make sure you followed this article first.
Notifier uses the files notify/transaction and listener/listener.

It can happen these file get corrupted for various reasons.

Step 0

It is recommended to stop the services during troubleshooting:

systemctl stop univention-directory-listener
systemctl stop univention-directory-notifier
systemctl stop slapd

For safety reason, do a backup of existing files:
tar -C /var/lib/univention-ldap -czpvf /root/replication_backup notify/ listener/

Step 1

Verify files

Option 1 (recommended for newer versions of UCS)

Verify by tool
For UCS 4.3-errata 470 and UCS 4.4-errata 33 you can use the command univention-translog to verify consistency of the files. The file are ok, when you do not get any output. Otherwise it might look like the following:

/usr/share/univention-directory-notifier/univention-translog check
2019-04-11 12:44:18,999:ERROR:/var/lib/univention-ldap/notify/transaction:2663:'2661 cn=nagios,cn=portal,cn=univention,dc=multi,dc=ucs d\n': Repeated line after '2662 cn=domain,cn=portal,cn=univention,dc=multi,dc=ucs m'
2019-04-11 12:44:20,825:ERROR:/var/lib/univention-ldap/notify/transaction:92499:'2661 cn=nagios,cn=portal,cn=univention,dc=multi,dc=ucs d\n': Repeated line after '2712 cn=rocketchat,cn=memberserver,cn=computers,dc=multi,dc=ucs m'

/var/lib/univention-ldap/notify/transaction needs fixing:
- the transactions are not sorted uniquely

You can re-run this tool with the option "--fix" in order to try to fix this issue.
See <> for more details.

Option 2 (for older versions)

For UCS prior to 4.3-errata 470 and UCS 4.4 prior to errata 33
The following script can be used (download link: (1,5 KB))

#!/usr/bin/env python
import ldap
for transactionfile in ('notify/transaction', 'listener/listener'):
  filepath = '/var/lib/univention-ldap/%s' % transactionfile
  print('Checking %s' % filepath)
  with open(filepath, 'r') as f:
    lc = 0
    for line in f:
      lc += 1
      head_tail = line.strip().split(' ', 1)
      if len(head_tail) != 2:
        print('ERROR missing second column at line %d: "%s"' % (lc, line))
      (id, tail) = head_tail
        cur_lc = int(id)
      except ValueError:
        print 'ERROR transactionID does not match line cound at line %d: "%s"' % (lc, line)
      head_tail = tail.rsplit(' ', 1)
      if len(head_tail) != 2:
        print 'ERROR missing third column at line %d: "%s"' % (lc, line)
      (dn, opcode) = head_tail
      if not ldap.dn.is_dn(dn):
        print 'ERROR not a valid DN at line %d: "%s"' % (lc, line)
      print('Syntax OK')

with open('/var/lib/univention-ldap/notify/transaction', 'r') as transaction:
  print('Checking %s for numbering issues' % filepath)
  lc = 0
  for line in transaction:
    lc += 1
    (id, tail) = line.strip().split(' ', 1)
      cur_id = int(id)
    except ValueError:
      print 'ERROR at line %d, does not start with an integer number: "%s"' % (lc, line)
    if lc == 1:
      start_id = cur_id
    if cur_id != (lc - 1 + start_id):
      print 'ERROR at line %d, transaction IDs not contiguous: "%s"' % (lc, line)
    print('Numbering OK')

Output might look like this:

root@master:~# python 
Checking /var/lib/univention-ldap/notify/transaction
Syntax OK
Checking /var/lib/univention-ldap/listener/listener
Syntax OK
Checking /var/lib/univention-ldap/listener/listener for numbering issues
ERROR at line 2663, transaction IDs not contiguous: "2661 cn=nagios,cn=portal,cn=univention,dc=multi,dc=ucs d

When copying this script into a terminal or file please make sure to keep the indentation, as the Python programming language depends on this.

Step 2

Fixing issues. The following output is from univention-translog. Using the script is not shown here but this would report similar errors.

Result 1 “not sorted uniquely

2019-04-11 14:28:30,869:ERROR:/var/lib/univention-ldap/notify/transaction:92961:'3122 uid=test29,cn=users,dc=multi,dc=ucs m\n': Repeated line after '3122 uid=test29,cn=users,dc=multi,dc=ucs m'

/var/lib/univention-ldap/notify/transaction needs fixing:
- the transactions are not sorted uniquely

Fix: In this case the tool should be able to fix autmatically by:

/usr/share/univention-directory-notifier/univention-translog check --fix

Result 2 “invalid command

2019-04-11 14:31:28,907:ERROR:/var/lib/univention-ldap/notify/transaction:3122:'3122 uid=test29,cn=users,dc=multi,dc=ucs k\n': Invalid command

/var/lib/univention-ldap/notify/transaction needs fixing:

Fix: Automated fix is not available. Valid commands are “m”, “r”, “a” or “d”. Check the lines and set the correct command. If in doubt set “m” as command.

Result 3 “invalid last id

2019-04-11 14:32:46,120:ERROR:/var/lib/univention-ldap/last_id: Invalid last id: should be 3123, but is 3122

/var/lib/univention-ldap/last_id needs manual fixing!

Fix: Automated fix is not available. Execute these commands:

tail -n 1 /var/lib/univention-ldap/notify/transaction
tail -n 1 /var/lib/univention-ldap/listener/listener
} | tail -n 1 | cut -d ' ' -f 1 > /var/lib/univention-ldap/last_id

Result 4 “unparseable lines

You got an error about IDs not being contiguos.
From univention-translog:

2019-04-11 14:22:07,697:ERROR:/var/lib/univention-ldap/notify/transaction:92961:'\xebc\x90\x10\x8e\xd0\xbc\x00\xb0\xb8\x00\x00\x8e\xd8\x8e\xc0\xfb\xbe\x00|\xbf\x00\x06\xb9\x00\x02\xf3\xa4\xea!\x06\x00\x00\n': Invalid line

/var/lib/univention-ldap/notify/transaction needs fixing:
- contains unparseable lines!

Fix: Automated fix is not available. Remove the lines as it does not contain valid information.

Result 5 “pending transactions are not consecutive”

2019-08-23 08:39:14,163:ERROR:/var/lib/univention-ldap/listener/listener:1:'20426 [...]: Not continuous with /var/lib/univention-ldap/notify/transaction: '20423 uid=[...] m'

Fix by adding the “--fix” command to the command:

root@ucs:~# /usr/share/univention-directory-notifier/univention-translog check --fix

Result 6 Any other message or " missing transactions in sequence"

The tool is not sure about the issue as it appears to have broken lines somehow. Remove the lines and retry.

Step 3

If you have been able to fix all errors restart the services:

systemctl start univention-directory-listener
systemctl start univention-directory-notifier
systemctl start slapd