​Polling ​Trigger

Trigger flows by polling external systems.

Polling triggers are a type of triggers that are provided by our plugins. They allow polling 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, ftp, ...

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

Example

For example, the following flow will be triggered when rows are available on the my_table PostgreSQL table, and when triggered, it will delete 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.