Crons

Crons on Lenra are a way to schedule tasks to be executed at specific times. A cron can be managed using the CRUD operations.

Creating a cron that runs each minute

To create a cron on Lenra, make a POST request to the /app-api/v1/crons endpoint with the following required parameters:

• listener_name: a string corresponding to the name of the listener on the application.
• schedule: a string corresponding to the cron 5 star format * * * * *.

The schedule parameter consists of five fields, each separated by a space, that represent minute, hour, day of the month, month, and day of the week. Here is the format:

* * * * *
- - - - -
| | | | |
| | | | +----- day of the week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of the month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)

Each field can take the following values:

• An asterisk (*) means "any value". For example, * * * * * would run the job every minute, every hour, every day of the month, every month, and every day of the week.

• A single value specifies a specific value for that field. For example, 0 * * * * would run the job at the beginning of every hour, and 0 0 1 * * would run the job at midnight on the first day of every month.

• A range of values specifies a range for that field. For example, 0 9-17 * * * would run the job every minute between 9 AM and 5 PM.

• A list of values specifies a list of values for that field. For example, 0 0 1,15 * * would run the job at midnight on the first and fifteenth days of every month.

• A step value specifies a value that the field must be evenly divisible by. For example, */15 * * * * would run the job every 15 minutes, and 0 0 */2 * * would run the job every other day.

You can also pass props to the request body for additional data that will be sent to the listener, for example:

{
  "listener_name": "myListener",
  "schedule": "* * * * *",
  "props": {
    "userId": "1234"
  }
}

The response will contain the created cron with the additional generated name parameter:

{
  "name": "5c18337c4de4a4a60ce4a6ee",
  "listener_name": "myListener",
  "schedule": "* * * * *",
  "props": {
    "userId": "1234"
  }
}

You will need to remember this name to properly call the UPDATE and DELETE endpoints that are under /crons/:name.