[Pgpool-hackers] Reload does not help if password file changed

[Tatsuo Ishii]

Thanks for report and patches. I will take care of this.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> Hi,
> 
>     Maybe this is expected behaviour, but it definitely is not desirable. If
> we add a new user:passwrod to the contents of pool_passwd file and send a
> reload signal to pgpool, the child processes are still not able to honor the
> new user and the trying to login using the new user causes error "MD5
> authentication failed..."
> 
>     I have diagnosed it back to the fact that pgpool uses stdio.h interface
> (FILE *) to access the pool_passwd file, and it reads the contents of the
> file for every new login that requests MD5 authentication. The problem with
> the stdio.h interface is that it caches the contents of the file and it does
> not refresh the cache even when the contents of the file change on-disk, so
> every time pgpool tries to read new user's password it does not see the new
> entry and hence fails.
> 
>     To be able to connect as the new user we have to either restart pgpool
> or wait for a new child to be forked which will see the new contents of the
> file. All of these problems also apply to the case where we might alter the
> password of an existing user and update the md5 password in pool_passwd
> file.
> 
>     I have attached a minimal patch to address this issue. In the patch, we
> save the file path that was initially used to open the pool_passwd and upon
> every reload the child closes and reopens the file so that the stdio.h
> interface does not show it cached data.
> 
> Regards,
> -- 
> Gurjeet Singh
> EnterpriseDB Corporation
> The Enterprise PostgreSQL Company