Editions and extensions

apowerb is an open core. The published package is a complete, generic server — not a crippled build waiting for a licence key.

Absent, not disabled

Commercial capabilities — identity-provider login, multi-factor authentication, token accounting and quotas, billing, B2B prospecting — are not present in the open-source build. There is no feature flag to flip and no dead code in the image. That distinction is observable on a running stack:

GET /api/config           → no "billing_enabled" key
GET /api/usage/quota      → 404
GET /api/billing/packages → 404
GET /api/auth/mfa/status  → 404

A missing key and a key set to false do not say the same thing. The first says the capability does not exist in this edition. Client code should treat an absent key as “not in this edition”, never as “disabled”.

The extension mechanism

Bricks are plugged in by naming their Python module in TH2_EXTENSIONS, as a comma-separated list. Each module exposes a register(registry) function — or, historically, init_overlay(registry). Both entry-point names are accepted.

TH2_EXTENSIONS=mycompany_pack.entrypoint,mycompany_connector

At startup the loader imports each module in order and calls its entry point, letting it register routers, tools and services against the core registry. Registered routers are mounted after the core’s own. TH2_OVERLAY_MODULE is the older single-module form. It is still honoured and is loaded after everything listed in TH2_EXTENSIONS. With neither variable set, no extension loads and the core stays generic and complete in itself. That property is what makes publishing the core alone possible.

Failures are loud

Any error while loading an extension propagates and stops startup. A broken extension must be visible to the healthcheck, never degrade the service silently. An extension that exposes neither register nor init_overlay raises at load time.

Writing an extension

# mycompany_pack/entrypoint.py
from fastapi import APIRouter

router = APIRouter(prefix="/api/mycompany", tags=["mycompany"])


@router.get("/ping")
def ping() -> dict[str, str]:
    return {"status": "ok"}


def register(registry) -> None:
    registry.add_router(router)

Installing an extension and loading it are two different steps. Adding the package to the environment does nothing on its own — the module must also be named in TH2_EXTENSIONS. A stack that installs the brick but forgets the variable starts healthy, answers 200, and silently lacks the capability.

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Editions and extensions

Absent, not disabled

The extension mechanism

Failures are loud

Writing an extension

​Absent, not disabled

​The extension mechanism

​Failures are loud

​Writing an extension

Absent, not disabled

The extension mechanism

Failures are loud

Writing an extension