## Problem
We want to show connection counts to console users.
## Summary of changes
Start exporting connection counts grouped by database name and
connection state.
## Problem
We want to report how much cache was used and what the limit was.
## Summary of changes
Added one more query to sql_exporter to expose
`neon.file_cache_size_limit`.
- Start pgbouncer in VM from postgres user, to allow connection to
pgbouncer admin console.
- Remove unused compute_ctl options --pgbouncer-connstr
and --pgbouncer-ini-path.
- Fix and cleanup code of connection to pgbouncer, add retries
because pgbouncer may not be instantly ready when compute_ctl starts.
## Problem
We need to add one more patch to pgbouncer (for
https://github.com/neondatabase/neon/issues/5801). I've decided to
cherry-pick all required patches to a pgbouncer fork
(`neondatabase/pgbouncer`) and use it instead.
See
https://github.com/neondatabase/pgbouncer/releases/tag/pgbouncer_1_21_0-neon-1
## Summary of changes
- Revert the previous patch (for deallocate/discard all) — the fork
already contains it.
- Remove `libssl-dev` dependency — we build pgbouncer without `openssl`
support.
- Clone git tag and build pgbouncer from source code.
- add pgbouncer_settings section to compute spec;
- add pgbouncer-connstr option to compute_ctl.
- add pgbouncer-ini-path option to compute_ctl. Default: /etc/pgbouncer/pgbouncer.ini
Apply pgbouncer config on compute start and respec to override default spec.
Save pgbouncer config updates to pgbouncer.ini to preserve them across pgbouncer restarts.
pgbouncer 1.21.0 doesn't play nicely with DEALLOCATD/DISCARD ALL if
prepared statement support is enabled (max_prepared_statements > 0).
There's a patch[0] that improves this (it will be included in the next
release of pgbouncer).
This PR applies this patch on top of 1.21.0 release tarball.
For some reason, the tarball doesn't include `test/test_prepared.py`
(which is modified by the patch as well), so the patch can't be applied
clearly. I use `filterdiff` (from `patchutils` package) to apply
the required changes.
[0] a7b3c0a5f4
