Pipeline with Results

Using task results in pipelines to pass data between tasks

Pipeline results aggregate outputs from tasks and make them available after the pipeline completes. This example also shows how task results create implicit dependencies.

Example

This is the same example as the simple pipeline, but focusing on the results aspect:

apiVersion: tekton.dev/v1
kind: Pipeline
metadata:
  name: sum-three-pipeline
spec:
  params:
    - name: first
      description: the first operand
    - name: second
      description: the second operand
    - name: third
      description: the third operand
  tasks:
    - name: first-add
      taskRef:
        name: add-task
      params:
        - name: first
          value: $(params.first)
        - name: second
          value: $(params.second)
    - name: second-add
      taskRef:
        name: add-task
      params:
        - name: first
          value: $(tasks.first-add.results.sum)  # Uses result from first-add
        - name: second
          value: $(params.third)
  results:
    - name: sum
      description: the sum of all three operands
      value: $(tasks.second-add.results.sum)
    - name: partial-sum
      description: the sum of first two operands
      value: $(tasks.first-add.results.sum)
    - name: all-sum
      description: the sum of everything
      value: $(tasks.second-add.results.sum)-$(tasks.first-add.results.sum)

How It Works

1. First Task Emits Result

   The first-add task completes and emits a result named sum containing the value 12 (2 + 10).

2. Second Task Waits and Uses Result

   The second-add task references $(tasks.first-add.results.sum), which creates an implicit dependency. Tekton ensures first-add completes before second-add starts.

3. Pipeline Results Are Computed

   After all tasks complete, the pipeline evaluates its result expressions. Each pipeline result can reference one or more task results.

4. Results Available in PipelineRun

   The computed results are stored in the PipelineRun status and can be queried using tkn pipelinerun describe or by checking the Kubernetes resource.

Referencing Task Results

Use this syntax to reference a task result:

$(tasks.TASK_NAME.results.RESULT_NAME)

Examples:

• $(tasks.first-add.results.sum) - Get the sum result from first-add task
• $(tasks.build.results.image-digest) - Get an image digest from a build task

Combining Results

Pipeline results can combine multiple task results:

results:
  - name: all-sum
    value: $(tasks.second-add.results.sum)-$(tasks.first-add.results.sum)

This produces: 22-12

Expected Output

After running with parameters (2, 10, 10):

tkn pipelinerun describe sum-three-pipeline-run

RESULTS
NAME           VALUE
sum            22
partial-sum    12
all-sum        22-12

Implicit Task Ordering

When a task references another task’s result, Tekton automatically:

1. Creates a dependency between the tasks
2. Ensures the producer task runs before the consumer task
3. Waits for the producer to complete successfully before starting the consumer

This means you don’t need to use runAfter when tasks have result dependencies.

Key Concepts

• Task Results: Output values from individual tasks
• Pipeline Results: Aggregated outputs from the entire pipeline
• Implicit Dependencies: Referencing a task’s result automatically creates a dependency
• Result Substitution: Use $(tasks.NAME.results.RESULT) syntax to access task results
• Result Composition: Pipeline results can combine multiple task results

Next Steps

• See parallel tasks for more complex dependencies
• Learn about multi-stage pipelines