Update debugging and env variables for Postgres spin up

[jaclark5]

PostgreSQL Snowflake Startup Changes

• Functional Improvement: Prefer pg_ctl found directly on PATH before falling back to pg_config-based discovery in PostgresHarness.

  • Why necessary: Prevents mixed PostgreSQL toolchains (for example, pg_config from one installation and pg_ctl/postgres from another), which can cause fragile startup behavior after package manager upgrades.
  • Platforms that benefit: macOS (especially Homebrew users), Linux systems with multiple PostgreSQL installs, and CI environments with layered tool paths.

• Debugging Enhancement: Include PostgreSQL logfile path and log tail in startup failures raised by PostgresHarness.start().

  • Why necessary: pg_ctl often returns generic errors like "could not start server"; surfacing log tail makes root-cause diagnosis immediate without manual file hunting.
  • Platforms that benefit: All platforms (macOS, Linux, Windows-like POSIX layers) where PostgreSQL logs are available.

• Functional Improvement: Add targeted detection of locale-related PostgreSQL startup failure and retry pg_ctl start once with LC_ALL=C and LANG=C.

  • Why necessary: Some environments export invalid locale state (for example empty LC_ALL), which can trigger PostgreSQL startup aborts; retrying only on known failure signatures avoids broad environment changes.
  • Platforms that benefit: Primarily macOS (where this failure was observed), and any Unix-like environment where locale configuration can be invalid in shell/notebook sessions.

• Functional Improvement: Add a PostgreSQL minimum version check in qcfractal/db_socket/socket.py before creating tables and running Alembic upgrades.

  • Why necessary: QCFractal schema features require PostgreSQL 15+ (for example NULLS NOT DISTINCT behavior in unique constraints); failing early with a clear message avoids hard-to-diagnose migration/runtime failures later.
  • Platforms that benefit: All platforms, especially environments with older default PostgreSQL versions (common on Linux distributions and long-lived workstation installs).

• Debugging Enhancement: Add explicit retry note text to the raised startup error when locale-safe retry was attempted.

  • Why necessary: Makes it clear in a single traceback whether fallback logic was used, reducing ambiguity during triage and PR review.
  • Platforms that benefit: All platforms.

Close #1000

Status

• Code base linted
• Ready to go

[bennybp]

looks mostly reasonable. I'm curious at what your set up is that is causing it to fail, though. I do search through $PATH. I do this manually, for some reason (I think because pg_config can be in a separate place the pg_ctl?).

Where are your your pg_config and pg_ctl located, and what does "pg_config --bindir" show?

[jaclark5]

pg_config --bindir

/opt/homebrew/bin/pg_config
/opt/homebrew/bin/pg_ctl
/opt/homebrew/Cellar/postgresql@15/15.17/bin

I can remove that part if you want. I think setting the env is really what fix my issue, but checking the path is something I tried first and didn't think it would hurt to leave it.

[jaclark5]

@bennybp would you prefer I remove the pg_config --bindir?