[Feat] Haproxy behaviour tuning

[a-b-v]

Problem

Long queries are abruptly terminated

Description

The HAProxy template includes:

default-server inter 3s fastinter 1s fall 3 rise 4 on-marked-down shutdown-sessions{% if patroni_restapi_protocol == 'https' %} check-ssl verify none{% endif %}

This ensures outdated replicas are not used, but it also causes long-running queries to be terminated when a replica is marked down.

Importance

nice to have

Proposed implementation

Add an option to make this behavior configurable (e.g., disable or customize shutdown-sessions), so users can avoid interrupting long-running queries when needed.

[vitabaks]

@a-b-v How long are your queries? Do they exceed haproxy_timeout?

[a-b-v]

No, they’re under 30 minutes, but replica lag can exceed the limit during that period

[vitabaks]

See patroni_maximum_lag_on_replica variable.

[a-b-v]

I’ve already adjusted this parameter, but I still think it would be useful to have the ability to disable this behavior.

[a-b-v]

So that new requests are executed on an up-to-date dataset, while allowing older long-running ones to finish.

[vitabaks]

Feel free to suggest PR