kestra Fundamentals

Flow

A flow is a container for tasks, their inputs, outputs, error handling, triggers and overall orchestration logic. It is defined in YANL and consists of below required components:

• id: Name of the flow, must be unique within a namespace.
• namespace: Can be used to separate development and production environments. Combination of id and namespace serves as a unique identifier for a flow.
• tasks: List of tasks that are executed in the order they are defined.

#This flow outputs "Hello World!" message to the kestra console
id: flow-name
namespace: production
description:
	# Getting started
	We can write `markdown` here
labels:
	owner: john.doe
	project: project_name
tasks:
 - id: hello-world
   type: io.kestra.plugin.core.log.Log
	 message: Hello World!
	 description: |
		 ## About this task
			This will print "Hello World!" to the logs

labels: Allows you to group flows using key:value pairs.

description: Document your flow’s purpose, supports markdown.

Tasks

Tasks are atomic actions for your flows, design your tasks to be small and granular, such as fetching data from a REST API or running a self-contained Python script.

• Tasks are defined as a list and will be executed sequentially.
• Flowable Tasks: These are tasks that can run in parallel, iterating over a list of items, or allow failure of specific tasks.

A task must have an id and a type, and you can use Ctrl + Space for Autocomplete to populate the list of tasks.

For example, Core Tasks, io.kestra.plugin.core.flow are commonly used to control the flow logic.

Inputs