Re: Trouble setting up replication

On 10/10/2015 12:02 PM, Chuck Martin wrote:
>
>> On Sep 5, 2015, at 5:37 PM, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>>
>> On 09/05/2015 02:27 PM, Chuck Martin wrote:
>>>> On Sep 5, 2015, at 4:29 PM, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>>>>
>>>> On 09/05/2015 11:00 AM, Chuck Martin wrote:
>>
>>>>>
>>>>> I had added to my pg_hba.conf
>>>>>
>>>>> host replication rep 64.207.10.121/32 cert
>>>>
>>>> From the above the only user that can use replication connecting from 64.207.10.121/32 is rep. You did not specify a -U in your connection above and ran the command as root so pg_basebackup used that as the user, which is the default behavior:
>>>>
>>>> http://www.postgresql.org/docs/9.4/interactive/libpq-connect.html#LIBPQ-PARAMKEYWORDS
>>>> "
>>>> user
>>>>
>>>> PostgreSQL user name to connect as. Defaults to be the same as the operating system name of the user running the application.
>>>> "
>>>>
>>>> There is no pg_hba entry for database replication and user root so the connection was rejected. To repeat, get out of the habit of running Postgres commands as root, it is not necessary. What matters is the Postgres user you are connecting as. When using replication, which is what pg_basebackup is doing, you need to connect as a user with sufficient privileges:
>>>>
>>>> http://www.postgresql.org/docs/9.4/interactive/app-pgbasebackup.html
>>>>
>>>> ".. The connection must be made with a superuser or a user having REPLICATION permissions (see Section 20.2), and pg_hba.conf must explicitly permit the replication connection. .."
>>>>
>>>> Whatever user you choose to do this with then needs to authorized in pg_hba.conf.
>>>
>>> This is very helpful. I understood that pb_basebackup was for creating a backup for replication purposes, but did not understand that PG needs the same permissions for it as for the replication itself. I ran it as user “postgres” and not as “rep”. I think I understand my error, but will study the links you included to make sure.
>>
>> Well the postgres user is a superuser so it will have the permissions to run pg_basebackup. The problem is that your pg_hba.conf did not authorize the postgres user to connect to the replication 'database' only the rep user. That mismatch is what needs to corrected, assuming the rep user has replication permissions.
>>
>>>
>>> Thanks for your help, Adrian. I think I’ll get this working now.
>>>
>>> Chuck
>
> I continue to struggle with this, but have solved many of the problems I caused. I now have the permissions corrected. But when I run pg_basebackup from the replicant/slave server, it returns an error that the server version 9.3.1 is unsupported.
>
> # pg_basebackup -V
> pg_basebackup (PostgreSQL) 9.2.13
>
> The replicant is on CentOS 7, and the main/master is on CentOS 6. I have installed PostgreSQL 9.3 on both. On the main/master server, I get:
>
> # pg_basebackup -V
> pg_basebackup (PostgreSQL) 9.3.1
>
> I only find one version of pg_basebackup on the replicant server, but CentOS 7 comes with PG 9.2, so I suspect that pg_basebackup is left over from that installation. But I’m not sure how to update that. yum update pg_basebackup did not work.

See John's reply.
>
> Any ideas? Or should I just change gears and execute pg_basebackup on the main/master instead?

Yes, you just need to point it at the -D for the standby assuming that
directory is empty. Also are you sure that Postgres 9.3 is running on
the standby?

>
> Chuck Martin
> Avondale Software
> 123 N. McDonough St.
> Decatur, GA 30030
> 404-373-3116, fax 404-373-4110
> clmartin(at)theombudsman(dot)com
>
>
>
>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com