Documented steps

Install the SDK: `pip install inngest`.
Create the client: `inngest_client = inngest.Inngest(app_id="fast_api_example", logger=logging.getLogger("uvicorn"))`. `app_id` is required; a hyphenated slug is recommended.
Supply credentials via `INNGEST_EVENT_KEY` and `INNGEST_SIGNING_KEY` environment variables, or the `event_key` / `signing_key` constructor arguments.
For local development set `INNGEST_DEV` or pass `is_production=False` so the client targets the Dev Server.
Define a function with the decorator: `@inngest_client.create_function(fn_id="import-product-images", trigger=inngest.TriggerEvent(event="shop/product.imported"))` over `async def fn(ctx: inngest.Context) -> str:`.
Triggers: `inngest.TriggerEvent(event=..., expression=...)` for events with an optional CEL filter, `inngest.TriggerCron(cron="0 12 * * 5", jitter="30s")` for schedules, or a list of either for multiple triggers.
Use the context object inside the handler: `ctx.event`, `ctx.events`, `ctx.attempt`, `ctx.run_id`, `ctx.logger`, `ctx.step`.
Wrap side effects in steps: `result = await ctx.step.run("step_id", some_async_callable, *args)`. The step object also exposes `send_event`, `sleep`, `sleep_until` and `_experimental_parallel`.
Mount the serve handler: `import inngest.fast_api` then `inngest.fast_api.serve(app, inngest_client, [my_function])`. Ref: https://www.inngest.com/docs/getting-started/python-quick-start
Start the Dev Server against the FastAPI endpoint and confirm the function registers.

Known gotchas

`_experimental_parallel` is named experimental for a reason — its API may change; do not build production fan-out on it without pinning the SDK version.
Step callables are passed as a function reference plus args (`ctx.step.run("id", fn, *args)`), not as a lambda closure over mutable state — closing over outer variables defeats memoization guarantees.
Durability rules are identical to the TypeScript SDK: anything outside `ctx.step.run` re-executes on every attempt.
Flask and Django integrations exist but are documented via example apps in https://github.com/inngest/inngest-py rather than inline docs — read the repo examples rather than guessing module names.
The quick-start uses `async def` handlers; confirm sync-handler support against your installed version before writing blocking code.
Function ids must be stable across deploys, same as TypeScript — `fn_id` is the memoization key.

inngest.com · 5 steps · unrated

Define an Inngest function and serve it from a Next.js App Router route handler

www.inngest.com/docs · 7 steps · unrated

Run Inngest functions locally with the Dev Server and sync them to production

www.inngest.com/docs/local-development · 8 steps · unrated

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Create and serve Inngest functions in Python with the FastAPI integration

Documented steps

Known gotchas

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