A Countdown powered by the Resonate Typescript SDK and Google Cloud Functions. The countdown sends periodic notifications to ntfy.sh at configurable intervals.
The Countdown is implemented with Resonate's Durable Execution framework, Distributed Async Await. The Countdown is a simple loop that can sleep for hours, days, or weeks. On yield ctx.sleep the countdown function suspends (terminates), immediately completing the Google Cloud Function execution. After the specified delay, Resonate will resume (restart) the countdown function by triggering a new Google Cloud Function execution.
export function* countdown(
ctx: Context,
count: number,
delay: number,
url: string,
) {
for (let i = count; i > 0; i--) {
// send notification to ntfy.sh
yield* ctx.run(notify, url, `Countdown: ${i}`);
// sleep creates a suspension point causing
// the Google Cloud Function execution to terminate
yield* ctx.sleep(delay * 60 * 1000);
}
// send the last notification to ntfy.sh
yield* ctx.run(notify, url, `Done`);
}Key Concepts:
- Suspension and Resumption: Executions can be suspended for any amount of time
- Stateful executions on stateless infrastructure: Short-lived function instances executing one step of a long-lived execution coordinated by the Resonate Server.
You can run the Countdown locally on your machine with Google's Functions Framework or you can deploy the Countdown to Google Cloud Platform.
Install the Resonate Server & CLI with Homebrew or download the latest release from Github.
brew install resonatehq/tap/resonate
Start the Resonate Server. By default, the Resonate Server will listen at http://localhost:8001.
resonate dev
Clone the repository
git clone https://github.com/resonatehq-examples/example-countdown-ts-gcp
cd example-countdown-ts-gcp
Install dependencies
npm install
Start the Google Cloud Function. By default, the Google Cloud Function will listen at http://localhost:8080.
npm run dev
The examples use ntfy.sh to send notifications. Create a unique channel name (to avoid receiving notifications from other users) and open the ntfy.sh channel in your browser.
echo https://ntfy.sh/resonatehq-$RANDOM
Start a countdown
resonate invoke <promise-id> --func countdown --arg <count> --arg <delay-in-minutes> --arg https://ntfy.sh/<channel> --target <function-url>
Example
resonate invoke countdown.1 --func countdown --arg 5 --arg 1 --arg https://ntfy.sh/resonatehq-22012 --target http://localhost:8080
Use the resonate tree command to visualize the countdown execution.
resonate tree countdown.1
Example output (while waiting on the second sleep):
countdown.1
├── countdown.1.0 🟢 (run)
├── countdown.1.1 🟢 (sleep)
├── countdown.1.2 🟢 (run)
└── countdown.1.3 🟡 (sleep)
This section guides you through deploying the countdown example to Google Cloud Platform using Cloud Run for the Resonate server and Cloud Functions for the countdown function.
Install the Resonate CLI with Homebrew or download the latest release from Github.
brew install resonatehq/tap/resonate
Ensure you have a Google Cloud Platform account, a project, and the necessary permissions as well as the Google Cloud CLI installed and configured.
Warning
Google Cloud Platform offers extensive configuration options. The instructions in this guide provide a baseline setup that you will need to adapt for your specific requirements, organizational policies, or security constraints.
Deploy the Resonate Server with its initial configuration.
Step 1: Initial deployment
gcloud run deploy resonate-server \
--image=resonatehqio/resonate:latest \
--region=us-central1 \
--allow-unauthenticated \
--timeout=300 \
--port=8080 \
--min-instances=1 \
--max-instances=1 \
--args="serve,--api-http-addr=:8080"
Step 2: Configuration
Configure the Resonate Server with its URL.
export RESONATE_URL=$(gcloud run services describe resonate-server --region=us-central1 --format='value(status.url)')
gcloud run services update resonate-server \
--region=us-central1 \
--args="serve,--api-http-addr=:8080,--system-url=$RESONATE_URL"
Print the Resonate Server URL
echo $RESONATE_URL
To view the Resonate Server logs
gcloud run services logs read resonate-server --region=us-central1 --limit=50
Deploy the countdown function to Cloud Functions.
gcloud functions deploy countdown \
--gen2 \
--runtime=nodejs20 \
--region=us-central1 \
--source=. \
--entry-point=handler \
--trigger-http \
--allow-unauthenticated
Get the function URL:
export FUNCTION_URL=$(gcloud functions describe countdown --gen2 --region=us-central1 --format='value(serviceConfig.uri)')
Print the Cloud Function URL
echo $FUNCTION_URL
To view the Cloud Function logs
gcloud functions logs read countdown --gen2 --region=us-central1 --limit=50
The examples use ntfy.sh to send notifications. Create a unique channel name (to avoid receiving notifications from other users) and open the ntfy.sh channel in your browser.
echo https://ntfy.sh/resonatehq-$RANDOM
Start a countdown
resonate invoke <promise-id> --func countdown --arg <count> --arg <delay-in-minutes> --arg https://ntfy.sh/<channel> --target $FUNCTION_URL --server $RESONATE_URL
Example
resonate invoke countdown.1 --func countdown --arg 5 --arg 1 --arg https://ntfy.sh/resonatehq-22012 --target $FUNCTION_URL --server $RESONATE_URL
Use the resonate tree command to visualize the countdown execution.
resonate tree countdown.1 --server $RESONATE_URL
Example output (while waiting on the second sleep):
countdown.1
├── countdown.1.0 🟢 (run)
├── countdown.1.1 🟢 (sleep)
├── countdown.1.2 🟢 (run)
└── countdown.1.3 🟡 (sleep)
Delete the deployed services:
# Delete the Cloud Function
gcloud functions delete countdown --gen2 --region=us-central1 --quiet
# Delete the Cloud Run service
gcloud run services delete resonate-server --region=us-central1 --quiet
If everything is configured correctly, you will see notifications in your ntfy.sh workspace.
If you are still having trouble please open an issue.
