​Concepts and ​Expressions

This section lists key concepts and templating expressions. You can treat this section as a lookup reference anytime you need more details about a specific concept or expression.

Flowable Tasks

Flowable tasks control the orchestration logic — run tasks or subflows in parallel, create loops and conditional branching.

Runnable Tasks

Runnable tasks are data processing tasks incl. file system operations, API calls, database queries, etc. These tasks can be compute-intensive and are processed by workers.

Revision

Flows are versioned by default. Whenever you make any changes to your flows, a new revision is created. This allows you to rollback to a previous version of your flow if needed.

Secret

Secret is a mechanism that allows you to securely store sensitive information, such as passwords and API keys, and retrieve them in your flows.

Pebble Templating Engine

Pebble is a Java templating engine inspired by Twig and similar to the Python Jinja Template Engine syntax. Kestra uses it to dynamically render variables, inputs and outputs within the execution context.

Blueprints

Blueprints is a curated, organized, and searchable catalog of ready-to-use examples designed to help you kickstart your workflow.

Backfill

Backfills are replays of missed schedule intervals between a defined start and end date.

Task Runners

Task Runners are plugins capable of executing your tasks in remote environments.

Replay

Replay allows you to re-run a workflow execution from any chosen task run.

Expression

Kestra's expressions use Pebble Templating along with flow's execution context to render various flow and task properties.