Resonate¶

Resonate is a durable agent execution engine that makes long-running, failure-prone workflows reliable by persisting their state as durable promises. Every function call resolves to a promise written to the database before any work begins. If the process crashes, a new worker reads the last open promise and resumes from exactly that point.

resonate-on-scylladb is a Go implementation of the Resonate server protocol backed by ScyllaDB. ScyllaDB stores all promise, task, and schedule state; the Resonate server runs alongside your existing stack as a single binary.

Note

The Resonate server always runs on your own infrastructure. ScyllaDB (self-hosted or ScyllaDB Cloud) is the durable storage backend it connects to. You are not locked in to a hosted workflow service.

Prerequisites¶

Docker Compose
Python 3.12+ (for the verification example)

Self-hosted ScyllaDB¶

The resonate-on-scylladb repository ships a docker-compose.yaml that starts ScyllaDB and the Resonate server together. The ScyllaDB schema is applied automatically on first startup.

Clone the repository:

git clone https://github.com/resonatehq/resonate-on-scylladb.git
cd resonate-on-scylladb

Start ScyllaDB and the Resonate server:

docker compose --profile server up

The Resonate server is now listening on http://localhost:8001 and ScyllaDB is available on localhost:9042.

Note

The default docker-compose.yaml starts the server with --debug enabled, which recreates the ScyllaDB keyspace on every server restart. This is convenient for local development but means durable promises are lost when the server container restarts. To disable this behavior, remove --debug from the server’s command in docker-compose.yaml before running.

ScyllaDB Cloud¶

When using ScyllaDB Cloud as the backend, run the Resonate server on your own infrastructure and point it at your ScyllaDB Cloud cluster. The Resonate server is not hosted in ScyllaDB Cloud, only the durable storage is.

Clone the repository and build the server image:

git clone https://github.com/resonatehq/resonate-on-scylladb.git
cd resonate-on-scylladb
docker build --target server -t resonate-server .

Configure and start the server.

Find your contact points and credentials on the Connect tab of your cluster in the ScyllaDB Cloud Console, then run:

docker run -p 8001:8001 \
  -e SCYLLADB_HOSTS="node-0.your-cluster.datacenter.clusters.scylla.cloud,node-1.your-cluster.datacenter.clusters.scylla.cloud,node-2.your-cluster.datacenter.clusters.scylla.cloud" \
  -e SCYLLADB_USERNAME="<your-username>" \
  -e SCYLLADB_PASSWORD="<your-password>" \
  -e SCYLLADB_KEYSPACE="resonate" \
  resonate-server serve

Warning

Do not pass --debug to the server when connecting to a production ScyllaDB Cloud cluster. Debug mode recreates the keyspace on every server restart, deleting all durable promises.

Verify with the Python SDK¶

With the server running (either self-hosted or Cloud-backed), install the Resonate Python SDK:

pip install resonate-sdk

Write a minimal durable workflow (hello.py):

import asyncio
from resonate.context import Context
from resonate.resonate import Resonate


async def greet(ctx: Context, name: str) -> str:
    return f"Hello, {name}!"


async def main() -> None:
    resonate = Resonate(url="http://localhost:8001")
    resonate.register(greet)
    try:
        handle = resonate.run("greet.1", greet, "ScyllaDB")
        result = await handle.result()
        print(result)   # Hello, ScyllaDB!
    finally:
        await resonate.stop()


if __name__ == "__main__":
    asyncio.run(main())

Run the worker:

python hello.py

Expected output:

Hello, ScyllaDB!

Note

The first run may take up to a minute while ScyllaDB initializes the schema and the server processes the task. Subsequent runs with the same promise ID return immediately from the database.

The durable promise for greet.1 is now persisted in ScyllaDB. Kill and restart the worker with the same script, the result is served from the database and the function is not executed again.

Additional Resources¶

Was this page helpful?