On 31/01/2024 17:13, Jehan-Guillaume de Rorthais wrote:
On Wed, 31 Jan 2024 16:37:21 +0100
lejeczek via Users <users@clusterlabs.org> wrote:
On 31/01/2024 16:06, Jehan-Guillaume de Rorthais wrote:
On Wed, 31 Jan 2024 16:02:12 +0100
lejeczek via Users <users@clusterlabs.org> wrote:
On 29/01/2024 17:22, Ken Gaillot wrote:
On Fri, 2024-01-26 at 13:55 +0100, lejeczek via Users wrote:
Hi guys.
Is it possible to trigger some... action - I'm thinking specifically
at shutdown/start.
If not within the cluster then - if you do that - perhaps outside.
I would like to create/remove constraints, when cluster starts &
stops, respectively.
many thanks, L.
You could use node status alerts for that, but it's risky for alert
agents to change the configuration (since that may result in more
alerts and potentially some sort of infinite loop).
Pacemaker has no concept of a full cluster start/stop, only node
start/stop. You could approximate that by checking whether the node
receiving the alert is the only active node.
Another possibility would be to write a resource agent that does what
you want and order everything else after it. However it's even more
risky for a resource agent to modify the configuration.
Finally you could write a systemd unit to do what you want and order it
after pacemaker.
What's wrong with leaving the constraints permanently configured?
yes, that would be for a node start/stop
I struggle with using constraints to move pgsql (PAF) master
onto a given node - seems that co/locating paf's master
results in troubles (replication brakes) at/after node
shutdown/reboot (not always, but way too often)
What? What's wrong with colocating PAF's masters exactly? How does it brake
any replication? What's these constraints you are dealing with?
Could you share your configuration?
Constraints beyond/above of what is required by PAF agent
itself, say...
you have multiple pgSQL cluster with PAF - thus multiple
(separate, for each pgSQL cluster) masters and you want to
spread/balance those across HA cluster
(or in other words - avoid having more that 1 pgsql master
per HA node)
ok
These below, I've tried, those move the master onto chosen
node but.. then the issues I mentioned.
You just mentioned it breaks the replication, but there so little information
about your architecture and configuration, it's impossible to imagine how this
could break the replication.
Could you add details about the issues ?
-> $ pcs constraint location PGSQL-PAF-5438-clone prefers
ubusrv1=1002
or
-> $ pcs constraint colocation set PGSQL-PAF-5435-clone
PGSQL-PAF-5434-clone PGSQL-PAF-5433-clone role=Master
require-all=false setoptions score=-1000
I suppose "collocation" constraint is the way to go, not the "location" one.
This should be easy to replicate, 3 x VMs, Ubuntu 22.04 in
my case
-> $ pcs resource config PGSQL-PAF-5438-clone
Clone: PGSQL-PAF-5438-clone
Meta Attrs: failure-timeout=60s master-max=1 notify=true
promotable=true
Resource: PGSQL-PAF-5438 (class=ocf provider=heartbeat
type=pgsqlms)
Attributes: bindir=/usr/lib/postgresql/16/bin
datadir=/var/lib/postgresql/16/paf-5438 maxlag=1000
pgdata=/etc/postgresql/16/paf-5438 pgport=5438
Operations: demote interval=0s timeout=120s
(PGSQL-PAF-5438-demote-interval-0s)
methods interval=0s timeout=5
(PGSQL-PAF-5438-methods-interval-0s)
monitor interval=15s role=Master timeout=10s
(PGSQL-PAF-5438-monitor-interval-15s)
monitor interval=16s role=Slave timeout=10s
(PGSQL-PAF-5438-monitor-interval-16s)
notify interval=0s timeout=60s
(PGSQL-PAF-5438-notify-interval-0s)
promote interval=0s timeout=30s
(PGSQL-PAF-5438-promote-interval-0s)
reload interval=0s timeout=20
(PGSQL-PAF-5438-reload-interval-0s)
start interval=0s timeout=60s
(PGSQL-PAF-5438-start-interval-0s)
stop interval=0s timeout=60s
(PGSQL-PAF-5438-stop-interval-0s)
so, regarding PAF - 1 master + 2 slaves, have a healthy
pqSQL/PAF cluster to begin with, then
make resource prefer a specific node (with simplest variant
of constraints I tried):
-> $ pcs constraint location PGSQL-PAF-5438-clone prefers
ubusrv1=1002
and play with it, rebooting node(s) with OS' _reboot_
I at some point, get HA/resource unable to start pgSQL,
unable to elect a master (logs saying with replication
broken) and I have to "fix" pgSQL cluster outside of PAF,
using _pg_basebackup_
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