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Cron binding spec

Cron

Detailed documentation on the cron binding component

/operations/components/setup-bindings/supported-bindings/cron/

Component format

To setup cron binding create a component of type bindings.cron. See [this guide]({{< ref "howto-bindings.md#1-create-a-binding" >}}) on how to create and apply a binding configuration.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
  namespace: <NAMESPACE>
spec:
  type: bindings.cron
  version: v1
  metadata:
  - name: schedule
    value: "@every 15m" # valid cron schedule

Spec metadata fields

Field	Required	Binding support	Details	Example
schedule	Y	Input/Output	The valid cron schedule to use. See this for more details	`"@every 15m"`

Schedule Format

The Dapr cron binding supports following formats:

Character	Descriptor	Acceptable values
1	Second	0 to 59, or *
2	Minute	0 to 59, or *
3	Hour	0 to 23, or * (UTC)
4	Day of the month	1 to 31, or *
5	Month	1 to 12, or *
6	Day of the week	0 to 7 (where 0 and 7 represent Sunday), or *

For example:

30 * * * * * - every 30 seconds
0 15 * * * * - every 15 minutes
0 30 3-6,20-23 * * * - every hour on the half hour in the range 3-6am, 8-11pm
CRON_TZ=America/New_York 0 30 04 * * * - every day at 4:30am New York time

You can learn more about cron and the supported formats here

For ease of use, the Dapr cron binding also supports few shortcuts:

@every 15s where s is seconds, m minutes, and h hours
@daily or @hourly which runs at that period from the time the binding is initialized

Listen to the cron binding

After setting up the cron binding, all we need to do is listen on an endpoint that matches the name of our component. let's assume the is scheduled. Note that this will be made as a HTTP POST request. The example below shows how a simple Node.js Express application can receive calls on the /scheduled endpoint and write a message to the console.

app.post('/scheduled', async function(req, res){
    console.log("scheduled endpoint called", req.body)
    res.status(200).send()
});

If we run this, we'll see that the /scheduled endpoint is called every five minutes by the Dapr sidecar.

Binding support

This component supports both input and output binding interfaces.

This component supports output binding with the following operations:

delete

[Basic schema for a Dapr component]({{< ref component-schema >}})
[Bindings building block]({{< ref bindings >}})
[How-To: Trigger application with input binding]({{< ref howto-triggers.md >}})
[How-To: Use bindings to interface with external resources]({{< ref howto-bindings.md >}})
[Bindings API reference]({{< ref bindings_api.md >}})
Scheduled tasks with the Cron binding in Dapr

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