<!--
title: AWS Node Scheduled Weather example in NodeJS
description: This is an example of creating a function that runs as a cron job using the serverless 'schedule' event. It retrieves weather information at 10am (UTC) and emails it to a predefined recipient. 
layout: Doc
-->
# AWS Node Scheduled Weather Example

This is an example of creating a function that runs as a cron job using the serverless `schedule` event. It retrieves weather information at 10am (UTC) and emails it to a predefined recipient. For more information on `schedule` event check out the Serverless docs on [schedule](https://serverless.com/framework/docs/providers/aws/events/schedule/).

## Cron syntax

```pseudo
cron(Minutes Hours Day-of-month Month Day-of-week Year)
```

All fields are required and time zone is UTC only.

| Field         | Values         | Wildcards     |
| ------------- |:--------------:|:-------------:|
| Minutes       | 0-59           | , - * /       |
| Hours         | 0-23           | , - * /       |
| Day-of-month  | 1-31           | , - * ? / L W |
| Month         | 1-12 or JAN-DEC| , - * /       |
| Day-of-week   | 1-7 or SUN-SAT | , - * ? / L # |
| Year          | 1970-2199      | , - * /       |

Read the [AWS cron expression syntax](http://docs.aws.amazon.com/lambda/latest/dg/tutorial-scheduled-events-schedule-expressions.html) docs for more info on how to setup cron

## Setup

### DarkSky

Please visit https://darksky.net/dev/ to register for a free API token.

### Postmark

Please visit https://postmarkapp.com to register for a free Postmark account.

### Configuration

Upon setting up access to both external services, you'll be required to update the environment variables in `serverless.yml`:

```
environment:
  RECIPIENT: tom@carrotcreative.com
  DARK_SKY_API_KEY: abc123
  POSTMARK_API_KEY: abc123
  POSTMARK_SENDER: devops@carrotcreative.com
  LATITUDE: 40.702637
  LONGITUDE: -73.989406
```

## Deploy

In order to deploy the you endpoint simply run

```bash
serverless deploy
```

The expected result should be similar to:

```bash
Serverless: Packaging service...
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading service .zip file to S3 (1.87 MB)...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
...........
Serverless: Stack update finished...
Serverless: Removing old service versions...
Service Information
service: scheduled-weather-example
stage: dev
region: us-east-1
api keys:
  None
endpoints:
  None
functions:
  scheduled-weather-example-dev-weather: arn:aws:lambda:us-east-1:219106525755:function:scheduled-weather-example-dev-weather
```

There is no additional step required. Your defined schedule becomes active right away after deployment.

## Usage

To test your function remotely:

```bash
sls invoke -f weather  
```

The expected result should be similar to:

```json
{
  "success": true
}
```

## Additonal Resources

For more information on running cron with Serverless check out the [Tutorial: Serverless Scheduled Tasks](https://parall.ax/blog/view/3202/tutorial-serverless-scheduled-tasks) by Parallax.