Update run_backend.sh

[satybaldin]

Fix database configuration handling for PostgreSQL and SQLite

Summary

This PR improves the database configuration logic in the Convex startup script to ensure proper handling of PostgreSQL and SQLite connections.

Changes made

1. Ensured correct PostgreSQL connection flag order

   • The official Convex Discord community mentioned that --db postgres-v5 must come before the connection string.
   • Fixed the ordering issue in the script.

2. Added conditional SSL disabling for PostgreSQL

   • Introduced logic to conditionally add --do-not-require-ssl if the user explicitly sets it.
   • The flag is not included by default, ensuring security for production environments.

3. Fixed SQLite execution logic

   • SQLite should receive "${DB_FLAGS[@]}" "$DB_SPEC", while PostgreSQL should only receive "${DB_FLAGS[@]}".
   • This prevents SQLite from breaking due to unnecessary parameters.

4. Removed .env file parsing

   • The official Convex script does not load .env explicitly.
   • This aligns the behavior with the official implementation.

Remaining Issues / Suggestions

✅ This script now properly handles both PostgreSQL and SQLite, but a few improvements could be made in the future:

• Dynamic TLS handling for PostgreSQL instead of forcing --do-not-require-ssl.
• Better logging for database connection failures to help with debugging.
• More flexible configuration options, such as allowing users to override database flags.

This PR ensures that users can properly self-host Convex with PostgreSQL and SQLite without running into misconfiguration issues.

[emmaling27]

Hey @satybaldin! Thanks for the contribution. I already updated this in 62ef09a, so I'm closing this PR since it does the same thing. Thanks for finding this issue! It has been built and tested, and it's available here. The docs are updated with instructions on how to run with local Postgres here