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DBOS Class

The DBOS class is a singleton—you must instantiate it (by calling its constructor) exactly once in a program's lifetime. Here, we document its constructor and lifecycle methods. Decorators are documented here and context methods and variables here.

class dbos.DBOS​

DBOS(
    *,
    config: Optional[DBOSConfig] = None,
    fastapi: Optional[FastAPI] = None,
    flask: Optional[Flask] = None,
)

Parameters:

  • config: Configuration parameters for DBOS. See the configuration docs.
  • fastapi: If your application is using FastAPI, the FastAPI object. If this is passed in, DBOS automatically calls dbos.launch when FastAPI is fully initialized. DBOS also adds to all routes a middleware that enables tracing through FastAPI HTTP endpoints.
  • flask: If your application is using Flask, the flask object. If this is passed in, DBOS adds to all routes a middleware that enables tracing through Flask HTTP endpoints.

launch​

DBOS.launch()

Launch DBOS, initializing database connections and starting scheduled workflows. Should be called after all decorators run. You should not call a DBOS function until after DBOS is launched. If a FastAPI app is passed into the DBOS constructor, launch is called automatically during FastAPI setup.

Example:

from dbos import DBOS

# Initialize the DBOS object
DBOS()

# Define a scheduled workflow
@DBOS.scheduled("* * * * *")
@DBOS.workflow()
def run_every_minute(scheduled_time: datetime, actual_time: datetime):
    DBOS.logger.info("This is a scheduled workflow!")

# After all decorators run, launch DBOS
DBOS.launch()

Example using Flask:

from flask import Flask
from dbos import DBOS

app = Flask(__name__)
DBOS(flask=app)

@app.route("/")
@DBOS.workflow()
def test_workflow():
    return "<p>Workflow successful!</p>"

# After all decorators run, launch DBOS
DBOS.launch()

if __name__ == "__main__":
    app.run()

Assuming your file is main.py, run with python3 -m main (dev) or gunicorn -w 1 'main:app' -b 0.0.0.0:8000 (prod)

destroy​

DBOS.destroy(
    destroy_registry: bool = False
)

Destroy the DBOS singleton, terminating all active workflows and closing database connections. After this completes, the singleton can be re-initialized. Useful for testing.

Parameters:

  • destroy_registry: Whether to destroy the global registry of decorated functions. If set to True, destroy will "un-register" all decorated functions. You probably want to leave this False.

reset_system_database​

DBOS.reset_system_database()

Destroy the DBOS system database, resetting DBOS's internal state in Postgres. Useful when testing a DBOS application to reset the internal state of DBOS between tests. For example, see its use in the testing tutorial. This is a destructive operation and should only be used in a test environment.