Optimize PostgreSQL startup with pre-initialized Docker image

[kyleconroy]

Summary

This PR optimizes PostgreSQL test database startup by pre-initializing the database at Docker image build time and applying performance-tuned settings. This eliminates the ~1-2 second initdb cost on every container start and ensures consistent, fast test execution.

Key Changes

• New Dockerfile.postgres: Creates a fast-startup PostgreSQL image with:

  • Pre-initialized database at build time
  • Pre-applied performance settings (fsync=off, synchronous_commit=off, etc.)
  • Pre-configured pg_hba.conf for network access
  • Uses SIGINT for fast shutdown without crash recovery

• Docker integration improvements:

  • internal/sqltest/docker/postgres.go: Added logic to build and use the custom sqlc-postgres image instead of pulling postgres:16
  • Implements buildPostgresImage() to build from Dockerfile.postgres on first use
  • Implements postgresImageExists() to check if image is already built
  • Implements findRepoRoot() to locate the Dockerfile relative to the repository

• Native PostgreSQL setup enhancements:

  • internal/sqltest/native/postgres.go: Added pgFastSettings configuration and applyFastSettings() function to apply performance tuning to existing PostgreSQL installations
  • Implements restartPostgres() with fallback logic for different init systems (systemctl, service, pg_ctlcluster)
  • Includes idempotency check to avoid re-applying settings

• Test setup tool updates:

  • cmd/sqlc-test-setup/main.go: Added applyFastSettings() function to apply performance tuning during manual PostgreSQL setup
  • Implements detectPgConfigPath() to query the running server for postgresql.conf location

• Docker Compose update:

  • docker-compose.yml: Updated to build the custom Dockerfile.postgres instead of pulling the standard postgres:16 image

Implementation Details

• Performance settings applied across all PostgreSQL setup methods are consistent: fsync=off, synchronous_commit=off, full_page_writes=off, wal_level=minimal, etc.
• All implementations include idempotency checks using a marker comment ("# sqlc test optimizations") to prevent duplicate settings
• The Docker image uses gosu for proper privilege handling and pipes the Dockerfile to docker build - to avoid sending the entire repository as build context
• Native setup includes fallback logic for PostgreSQL restart across different Linux distributions

https://claude.ai/code/session_018Godbm3DFdWJf5jc7NU8Uq