Capture and Reuse Execution Results Across Tasks and Flows

Table of Contents

For the complete documentation index, see llms.txt. For a full content snapshot, see llms-full.txt. Append .md to any kestra.io/docs/* URL for plain Markdown.

Outputs let you pass data between tasks and flows.

Outputs are stored in the flow’s execution context and accessible by all downstream tasks and flows. Each task defines its own output attributes; see the task’s plugin documentation for details, or inspect them in the Input/Output tab of the Execution page.

Do not use outputs to fetch sensitive data such as passwords, secrets, or API tokens. All data fetched via outputs is stored in clear text in the backend database, internal storage, logs, and API responses. Use Secrets instead. Enterprise Edition and Kestra Cloud offer native integrations with external secrets managers.

Output reference syntax

Task outputs are referenced with {{ outputs.<task_id>.<attribute> }} in any dynamic property:

id: task_outputs_example
namespace: company.team

tasks:
  - id: produce_output
    type: io.kestra.plugin.core.debug.Return
    format: my output {{ execution.id }}

  - id: use_output
    type: io.kestra.plugin.core.log.Log
    message: The previous task output is {{ outputs.produce_output.value }}

File outputs are previewable and downloadable from the execution’s Input/Output tab; any output can be inspected and debugged using the built-in expression evaluator on the same tab. See Outputs in the tutorial.

For loop iteration outputs, sibling task outputs, and the loopOutputs() function, see Flowable tasks and the Loop how-to guide.

Internal storage

Tasks that produce large results write them to Kestra’s internal storage and return a URI. Downstream tasks reference the URI directly. For a full explanation of how internal storage works, including fetchType and file lifetime, see Data Storage.

id: output_sample
namespace: company.team

tasks:
  - id: output_from_query
    type: io.kestra.plugin.gcp.bigquery.Query
    sql: |
      SELECT * FROM `bigquery-public-data.wikipedia.pageviews_2023`
      WHERE DATE(datehour) = current_date()
      ORDER BY datehour desc, views desc
      LIMIT 10
    store: true

  - id: write_to_csv
    type: io.kestra.plugin.serdes.csv.IonToCsv
    from: "{{ outputs.output_from_query.uri }}"

Flow outputs

Flows can declare strongly typed outputs that are surfaced in the Overview tab and accessible to parent flows via the Subflow task:

id: flow_outputs
namespace: company.team

tasks:
  - id: mytask
    type: io.kestra.plugin.core.debug.Return
    format: this is a task output used as a final flow output

outputs:
  - id: final
    type: STRING
    value: "{{ outputs.mytask.value }}"

Supported output types: ARRAY, BOOLEAN, DATE, DATETIME, DURATION, EMAIL, ENUM, FILE, FLOAT, INT, JSON, MULTISELECT, SECRET, STRING, TIME, URI, YAML.

Child flow output access

A child flow’s declared outputs are accessible in the parent via {{ outputs.<subflow_task_id>.outputs.<output_id> }}:

id: parent_flow
namespace: company.team

tasks:
  - id: subflow
    type: io.kestra.plugin.core.flow.Subflow
    flowId: flow_outputs
    namespace: company.team
    wait: true

  - id: log_subflow_output
    type: io.kestra.plugin.core.log.Log
    message: "{{ outputs.subflow.outputs.final }}"

The double outputs is intentional: the first accesses the Subflow task’s outputs, the second accesses the child flow’s declared output final.

Conditional output values

A ternary expression selects between output values based on task state:

id: conditionally_return_output
namespace: company.team

inputs:
  - id: run_task
    type: BOOL
    defaults: true

tasks:
  - id: main
    type: io.kestra.plugin.core.debug.Return
    format: Hello World!
    runIf: "{{ inputs.run_task }}"

  - id: fallback
    type: io.kestra.plugin.core.debug.Return
    format: fallback output

outputs:
  - id: flow_output
    type: STRING
    value: "{{ tasks.main.state != 'SKIPPED' ? outputs.main.value : outputs.fallback.value }}"

Encrypted outputs

Available on:

v>=0.23Enterprise EditionCloud

Script tasks can emit encrypted outputs that are masked in the UI using the encryptedOutputs syntax:

id: encrypted_output
namespace: company.team

tasks:
  - id: hello
    type: io.kestra.plugin.scripts.shell.Script
    script: |
      echo '::{"outputs":{"plaintext":"plaintext_value"}}::'
      echo '::{"encryptedOutputs":{"encrypted":"my secret value"}}::'

  - id: print
    type: io.kestra.plugin.core.log.Log
    message: "{{ outputs.hello['vars']['encrypted'] }}"

The encrypted output is stored and displayed encoded. See Script outputs and metrics for full details.

ChecksChecks in Kestra – Pre-Execution Validations

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