[Samba] Log rotation issue

[Anantha Raghava]

Hello Andrew,

I am now experimenting with my test setup on the log rotation part.

While testing different scripts, I observed a very peculiar behavior 
with log writing process.

If the log file name has a variable to be substituted, say %T, it 
continues to write into it without creating .old file. If it is a simple 
name like samba.log or dc1.current.log etc., after about 10 MB, the log 
rotates,with or without my script and appends .old to actual log file 
and continues to write into .old file. Could you please provide pointers 
where to look for this log writing routine and why this peculiar 
behavior? My smb.conf and the script I am using is shown below.

Samba version is 4.7.1

/*smb.conf*/

# Global parameters
[global]
         netbios name = DC1
         realm = EXZA.COM
         server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc, 
drepl, winbindd, ntp_signd, kcc, dnsupdate
         workgroup = EXZA
         server role = active directory domain controller
         ldap server require strong auth = No
         log level = 10
         log file = /var/log/samba/dc1.current.log
         #"With this file name, the log gets rotated when it reaches 10 
MB or above in size, One cannot exactly say at what size it rotates. The 
process appends .old                 to the file name and continues to 
write into .old file."

[netlogon]
         path = /usr/local/samba/var/locks/sysvol/exza.com/scripts
         read only = No

[sysvol]
         path = /usr/local/samba/var/locks/sysvol
         read only = No/*
*/

/*Script used to rotate log*/

File size is set to 10 MB in this script. This script runs in background 
(not as a cron).
**/**/

#!/bin/bash
MaxFileSize=10000000
while true
do
     file_size=`du -b /var/log/samba/dc1.current.log | tr -s '\t' ' ' | 
cut -d' ' -f1`
     if [ $file_size -gt $MaxFileSize ];then
         timestamp=`date +%Y%m%d%H%M%S`
         cp -pr "/var/log/samba/dc1.current.log" 
"/var/log/samba/dc1.$timestamp.log.old"
         echo > /var/log/samba/dc1.current.log
     fi

done/*
*/

-- 

Thanks & Regards,


Anantha Raghava


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On 02/12/17 12:07 PM, Andrew Bartlett wrote:
> On Sat, 2017-12-02 at 11:58 +0530, Anantha Raghava wrote:
>> Hello Andrew,
>>
>> Thanks for proper explanation.
>>
>> To overcome this,  also as we need to store logs for long,  now we
>> have written a shell script,  executed as a crop every three minutes
>> that checks the file size.  If the file size is 1 GB or above,  it
>> moves the log file to <logfile>.timestamp.log.old and clears the main
>> log file.
>>
>> We have commented out the max log size in sub.conf.
>>
>> If need be I can share the script here
> I'm not sure that will help, that is pretty much what was happening
> before.  The key is to send a -HUP to the whole process tree to make
> them re-open the logs, otherwise the other child samba processes will
> still just write to the .old
>
> I know this sucks.  I think the solution is to have a new reopen-logs
> message created so this can be used in logroate, and to have it used
> internally as I mentioned.
>
> Andrew Bartlett