simplebroker-pg 1.4.0

Postgres backend plugin for SimpleBroker

simplebroker-pg

Postgres backend plugin for SimpleBroker.

This package is intentionally separate from simplebroker itself. SimpleBroker remains SQLite-first. This package adds a Postgres backend through the public backend plugin hook.

Requirements

• Python 3.10+
• PostgreSQL
• A dedicated schema for SimpleBroker tables

public is intentionally rejected.

Installation

# Fresh install through SimpleBroker's convenience extra
pipx install "simplebroker[pg]"

# Add to an existing pipx-installed simplebroker (recommended)
pipx inject simplebroker simplebroker-pg

# Or install through the convenience extra in a project
uv add "simplebroker[pg]"

# Or install the extension directly with uv
uv add simplebroker-pg

# Or install the extension directly with pip
pip install simplebroker-pg

simplebroker[pg] still installs this package as a separate distribution. Postgres support is not built into the default simplebroker install.

Python Usage

from simplebroker import Queue
from simplebroker_pg import PostgresRunner

runner = PostgresRunner(
    "postgresql://postgres@127.0.0.1:54329/simplebroker_test",
    schema="simplebroker_app",
)

queue = Queue("jobs", runner=runner, persistent=True)
try:
    queue.write("hello")
    print(queue.read())
finally:
    queue.close()
    runner.close()

Multi-Queue Activity Waiters

Postgres supports simplebroker.create_activity_waiter_for_queues(...) with one process-local shared LISTEN/NOTIFY listener per DSN and schema. The waiter wakes when any watched queue receives activity, ignores unrelated queue notifications, and returns the same ActivityWaiter | None shape as the core API.

Wakeups are hints. After wait(timeout) returns True, callers should still drain queues through normal SimpleBroker reads or moves. Close the multi-queue waiter explicitly when the watcher lifecycle ends.

CLI Usage

Create .broker.toml in the project root, or use the configured BROKER_PROJECT_CONFIG_PATH / BROKER_PROJECT_CONFIG_NAME location:

version = 1
backend = "postgres"
target = "postgresql://postgres@127.0.0.1:54329/simplebroker_test"

[backend_options]
schema = "simplebroker_app"

Then use the normal CLI from any child directory with project scope enabled:

broker init
broker write jobs hello
broker read jobs

You can also run entirely from environment variables without a project config:

BROKER_BACKEND=postgres \
BROKER_BACKEND_TARGET='postgresql://postgres@127.0.0.1:54329/simplebroker_test' \
BROKER_BACKEND_SCHEMA='simplebroker_app' \
BROKER_BACKEND_PASSWORD='postgres' \
broker init

Notes:

• In env-only backend configuration, BROKER_BACKEND_TARGET overrides the host/port/user/database parts.
• BROKER_BACKEND_HOST, BROKER_BACKEND_PORT, BROKER_BACKEND_USER, BROKER_BACKEND_PASSWORD, and BROKER_BACKEND_DATABASE are only used when there is no target from project config or env.
• When project TOML provides the target or schema, the project file wins. BROKER_BACKEND_PASSWORD can still be supplied from env and is never written to project TOML.
• The Postgres database must already exist. broker init creates the managed schema/tables inside that database; it does not create the database itself.
• Missing backend/plugin errors are distinct from target/auth errors. Invalid schema names, bad passwords, malformed targets, and missing databases are reported as validation or connection failures, not as "backend not available" errors.