[pgpool-general: 3693] Re: Watchdog/HA pgpool with external load balancer or similar

[James Sewell]

Hey Mark,

This kind of environment is certainly possible, we do a lot of work with
PGPool in AWS achieve some great results.

Generally speaking you can just have a pair of PGPool instances linked with
Watchdog and then put a load balancer in front of them. This can be an AWS
ELB, an appliance like an F5 or a software load balancer HAProxy.

In all of these cases you just need to teach the load balancer how to
health check PGPool - most of the time a TCP check will do.

In combination with this you need to tell PGPool not to worry about the
virtual IP address - you can do this by setting delegate_IP to nothing.

This will create an ACTIVE/ACTIVE PGPool environment, requests can come in
to both nodes and be serviced, if one goes down then the load balancers
will notice and remove it from the pool.

If you control your database failover with PGPool this will work out of the
box, if you control it with another product (linuxHA, repmgr, EnterpriseDB
PPFM) then you will need to teach that product how to fence PostgreSQL
nodes using either the AWS API or the PGPool PCP API.

Hope that helps.

Cheers,




James Sewell,
PostgreSQL Team Lead / Solutions Architect
______________________________________


 Level 2, 50 Queen St, Melbourne VIC 3000

*P *(+61) 3 8370 8000  *W* www.lisasoft.com  *F *(+61) 3 8370 8099


On Tue, May 5, 2015 at 8:23 AM, Mark Kirkwood <mark.kirkwood at catalyst.net.nz
> wrote:

> Hi,
>
> The watchdog examples all seem to expect that ppgool itself can control
> the ip to host allocation. While this works fine in my test setup, we are
> looking at deploying this in a more cloud-like environment where pgpool
> (and for that matter the hosts too) *cannot* change their own networking
> (in fact they may not even know their world accessible ips).
>
> Another type of config we are looking at is where an external load
> balancer controls the redirection to the pgpool hosts.
>
> So is it possible to setup a watchdog type arrangement, but with
> *something else* (as above) controlling the ip allocation?
>
>
> Cheers
>
> Mark
> _______________________________________________
> pgpool-general mailing list
> pgpool-general at pgpool.net
> http://www.pgpool.net/mailman/listinfo/pgpool-general
>

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