GitHub: dbos_experiments/exp1

Experiment 1

Summary

This experiment demonstrates a basic DBOS application with FastAPI integration, featuring workflow processing, queues, and database operations. It showcases user access management with error handling and observability through structured logging.

Files Description

Core Application Files

• main.py - Main application file containing:
  • FastAPI application setup with DBOS integration
  • Queue configuration with concurrency limits and rate limiting (50 functions per 30 seconds)
  • Workflow definitions for processing tasks and handling errors
  • Database transactions for storing access records and error logs
  • REST API endpoints:
    • POST /submit - Starts a workflow with predefined user IDs
    • POST /batch/{count} - Starts a batch workflow with repeated user IDs
    • GET /errors - Retrieves all errors from the database
  • Structured JSON logging configuration
  • Event-based workflow communication
• models.py - SQLAlchemy database models:
  • Base - SQLAlchemy declarative base class
  • Errors - Table for storing error messages as JSONB with timestamps
  • Users - User management table with name, email, and timestamps
  • Accesses - User access tracking with status enum (requested, approved, rejected, canceled)
  • Proper foreign key relationships between Users and Accesses

Configuration Files

• __init__.py - Python package initialization file (makes the directory a Python package)

• dbos-config.yaml - DBOS configuration file specifying database connections and application settings

• envrc-template - Template for environment variables (used with direnv for automatic environment loading)

Database Migration Files

• migrations/ - Alembic database migration directory containing:
  • alembic.ini - Alembic configuration file
  • env.py - Migration environment setup
  • README - Alembic documentation
  • script.py.mako - Template for generating migration scripts
  • versions/ - Directory containing actual migration files

Cache Files

• __pycache__/ - Python bytecode cache directory (automatically generated)

Development

Run docker compose in the parent directory:

docker compose up

Alembic

# alembic init migrations

# export ALEMBIC_CONFIG=migrations/alembic.ini

# alembic revision -m "initial migration"

alembic upgrade head

Generate models from the database

# sqlacodegen --generator declarative --options nojoined  --outfile models.py $POSTGRES_URL

DBOS

# Alternative to alembic upgrade head
# dbos migrate

dbos start

DB

To inspect the database:

pgcli

Recent changes

• 2026-01-17

  8e83110

  updated models

• 2025-08-10

  bdd71b7

  added AI READMEs

• 2025-07-18

  70c5044

  added dbos 1.7

• 2025-02-09

  b378615

  backup

• 2025-02-08

  950d93b

  exp1