​Polling ​Trigger

Trigger flows by polling external systems.

Polling triggers poll an external system for the presence of data. In case data is ready to be processed, a flow execution is started.

Kestra provides polling triggers for a wide variety of external systems, for example: databases, message brokers, and ftp.

Polling triggers poll the external system at a fixed interval defined by the interval property, the triggered flow has the outputs of the polling trigger available on the trigger variable.

Example

For example, the following flow triggers when rows are available on the my_table PostgreSQL table, and when triggered, it deletes the rows (to avoid processing them again on the next poll) and log them.

id: jdbc-trigger
namespace: company.team

inputs:
  - id: db_url
    type: STRING

tasks:
- id: update
  type: io.kestra.plugin.jdbc.postgresql.Query
  url: "{{ inputs.db_url }}"
  sql: DELETE * FROM my_table

- id: log
  type: io.kestra.plugin.core.log.Log
  message: "{{ trigger.rows }}"

triggers:
  - id: watch
    type: io.kestra.plugin.jdbc.postgresql.Trigger
    url: myurl
    interval: "PT5M"
    sql: "SELECT * FROM my_table"

Polling triggers can be evaluated on a specific Worker Group (EE), thanks to the workerGroup.key property.