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Thread: Notify When Streaming Replication Failover Occurred (slave promoted to master).

Notify When Streaming Replication Failover Occurred (slave promoted to master).

From
"Avi Weinberg"
Date:

I need to take actions when Postgres streaming replication failover occurred.  Is there a way to be notified when Postgres slave becomes master?  If no such notification possible, what is the best way to actively monitor which server is master.  My Postgres  is running inside Kubernetes and the HA is managed by Patroni.

 

Thanks!

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Re: Notify When Streaming Replication Failover Occurred (slave promoted to master).

From
Dave Cramer
Date:

On Sun, 13 Jun 2021 at 19:32, Avi Weinberg <AviW@gilat.com> wrote:

I need to take actions when Postgres streaming replication failover occurred.  Is there a way to be notified when Postgres slave becomes master?  If no such notification possible, what is the best way to actively monitor which server is master.  My Postgres  is running inside Kubernetes and the HA is managed by Patroni.

 


On the surface this seems like a great idea, however contemplating this a bit more; where would the signal come from ? Currently the only option I can think of is to send a NOTIFY. 
It seems to me that the Patroni code is a better place to do this from.

Dave

Re: Notify When Streaming Replication Failover Occurred (slave promoted to master).

From
"Peter J. Holzer"
Date:
On 2021-06-14 08:10:58 -0400, Dave Cramer wrote:
> On Sun, 13 Jun 2021 at 19:32, Avi Weinberg <AviW@gilat.com> wrote:
>
>
>     I need to take actions when Postgres streaming replication failover
>     occurred.  Is there a way to be notified when Postgres slave becomes
>     master?
>
> On the surface this seems like a great idea, however contemplating this a bit
> more; where would the signal come from ? Currently the only option I can think
> of is to send a NOTIFY. 
> It seems to me that the Patroni code is a better place to do this from.

I agree. That is something Patroni should do, not the database. Maybe
Patroni could be extended to invoke a script after taking some action.

I know of one program (vip_manager) which monitors patroni state and
takes action (enable/disable virtual ip addresses) - that one checks the
distributed database (etcd or whatever) periodically, AFAIK.

        hp

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