Awesome

Nowcasting Alerts Cron Workers

The repo nowcasting_alerts contains the main Remix application for managing alerts. But Cloudflare Pages does not support ScheduledEvents (cron). So this separate repo houses cron worker functions. Learn more at https://developers.cloudflare.com/workers/runtime-apis/scheduled-event/

We use npm workspaces (npm version 7+) to manage multiple package.json files (a separate package is required for each Cloudflare Worker).

Workers

deviation

Checks for a deviation in the PV_Live and Nowcasting forecasts, and sends a webhook to all configured alerts if there is.

daily_max

Runs every morning at 7am UTC and finds the highest forecast for the day, and sends it as a webhook to all configured alerts.

Running locally

npm i

1. For each Cloudflare Worker (directories in root, e.g. daily_max), make a copy of wrangler.toml.example and rename it to wrangler.toml.
2. You'll need to grab the Auth0 CLIENT_ID and CLIENT_SECRET from the Auth0 dashboard in the "Alerts App" Machine-to-Machine application. and paste them into the wrangler.toml file under [vars] for each Worker.
3. The wrangler.toml file for each Worker also needs the kv_namespaces section filled in with the KV namespace IDs for the nowcasting-alerts-ALERTS and nowcasting-alerts-LOG KV namespaces. If you're running locally, you'll also need to add a "preview_id" for each KV namespace, these can also be found using the CF Dashboard or the CLI. You can find these in the Cloudflare dashboard main nav Workers > KV.
4. Run worker locally either with:

npm run dev --workspace=[Cloudflare Worker folder name]

5. Run curl "http://localhost:8787/cdn-cgi/mf/scheduled" to trigger the scheduled event Go back to the console to see what your worker has logged

or

Sometimes the preview KV doesn't seem to sync properly, so you can run the worker locally with:

npx wrangler dev --test-scheduled

Similarly, you can then ping the worker with:

curl "http://localhost:8787/__scheduled"

N.B. Wrangler can pick up the KV variables from the wrangler.toml file, but it doesn't seem to pick up variables from an .env file, so they have to be in the wrangler.toml file.

If you want to use an .env file, you can put the Auth0 variables in there, but you'll need to add the KV variables to the wrangler.toml file still.

Production

Setup KV for production

Data for this app is stored using Cloudflare key-value storage (when setting up the main repo you will have already done:

• Create KV namespaces: nowcasting-alerts-ALERTS, nowcasting-alerts-LOG)
• Copy wrangler.toml.example to wrangler.toml Go to Cloudflare dashboard main nav Workers > KV and copy the IDs for nowcasting-alerts-ALERTS, nowcasting-alerts-LOG then paste them into the kv_namespaces in wrangler.toml

If you add a new worker, ensure you create a preview KV namespace for both ALERTS and LOG:

npx wrangler kv:namespace create "LOG" --preview
npx wrangler kv:namespace create "ALERTS" --preview
npx wrangler kv:namespace create "STORAGE" --preview

and add the IDs to the wrangler.toml file for the new worker under "preview_id". You can find these in the Cloudflare dashboard main nav Workers > KV, or manage from the CLI:

# List all KV namespaces
npx wrangler kv:namespace list

# List all KV keys in a specific namespace that is bound to the current Worker (if in that directory)
npx wrangler kv:key list --binding=ALERTS [--preview]

# Get the value of a specific KV key in a namespace that is bound to the current Worker (if in that directory)
npx wrangler kv:key get --binding=ALERTS [--preview] <key_id>

# Put a value into a specific KV key in a namespace that is bound to the current Worker (if in that directory)
npx wrangler kv:key put --binding=ALERTS [--preview] <key_id> [value]

Deployment

• Ensure the Auth0 environment variables are set in the Cloudflare dashboard Workers > [worker-name] > Settings > Environment Variables and are encrypted. These should be set already.
• Publish all the Workers to Cloudflare:

npm run publish --workspaces

• Or deploy to production an individual Worker:

npm run deploy --workspace=[Cloudflare Worker name]

Limitations

There are some permission issues when installing wrangler as a dependency in an npm workspace. As a workaround, I've made wrangler a dependency in the top-level package.json for the overall monorepo, and omitted wrangler from the dependencies for each workspace. That means that the npm scripts in each workspace depend on wrangler being installed outside of the workspace. So if you wanted to pull a workspace out of the monorepo and run the workspace on its own, you must re-add wrangler to the workspace dependencies first.