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

To dynamically set values for your tasks and flows, you can add an expression by using {{ expression_name }} syntax. Dynamic expressions can be used on each task property that is documented as dynamic.

Kestra uses an integrated templating engine to dynamically render variables, inputs and outputs within the execution context.

Flows, tasks, executions, triggers, and schedules have default expressions. For example, {{ }} allows accessing the identifier of a flow within an execution.

Flow inputs can be accessed using {{ inputs.myinput }}, and task's output attributes are available as {{ outputs.task_id.output_attribute }} expressions.

Most expressions are stored in the execution context. The execution context encompasses flow and execution, environment variables, global variables, task defaults, flow inputs, and task outputs. Expressions of a FILE-type are stored in Kestra's internal storage and fetched from there at execution time.