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A StepAction is a reusable and scriptable unit of work that is performed by a Step. StepActions enable you to share common Step logic across multiple Tasks.
StepActions is a stable feature.

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Overview

A Step is not reusable on its own, but the work it performs can be extracted into a StepAction and referenced by multiple Steps. Key concepts:
  • Steps are inlined in Task definitions and either perform work directly or reference a StepAction
  • A StepAction cannot run standalone (unlike TaskRuns or PipelineRuns)
  • A Step has the ability to reference a StepAction for its work
  • The Step provides orchestration and context to the StepAction

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Configuring a StepAction

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Required Fields

  • apiVersion - Specifies the API version (e.g., tekton.dev/v1alpha1)
  • kind - Must be StepAction
  • metadata - Uniquely identifies the StepAction (e.g., name)
  • spec - Configuration for the StepAction
  • image - Container image to use for the Step

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Optional Fields

  • command - Cannot be used with script
  • args - Command arguments
  • script - Cannot be used with command
  • env - Environment variables
  • params - Parameter declarations
  • results - Result declarations
  • workingDir - Working directory
  • securityContext - Security context
  • volumeMounts - Volume mounts
  • description - User-facing description

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Basic Example

apiVersion: tekton.dev/v1beta1
kind: StepAction
metadata:
  name: example-stepaction-name
spec:
  env:
    - name: HOME
      value: /home
  image: ubuntu
  command: ["ls"]
  args: ["-lh"]

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Parameters

StepActions declare parameters just like Tasks, supporting string, array, and object types.

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Declaring Parameters

apiVersion: tekton.dev/v1beta1
kind: StepAction
metadata:
  name: stepaction-using-params
spec:
  params:
    - name: gitrepo
      type: object
      properties:
        url:
          type: string
        commit:
          type: string
    - name: flags
      type: array
    - name: outputPath
      type: string
      default: "/workspace"
  image: some-git-image
  args: [
    "-url=$(params.gitrepo.url)",
    "-revision=$(params.gitrepo.commit)",
    "-output=$(params.outputPath)",
    "$(params.flags[*])",
  ]
Parameters cannot be directly used in script in StepActions. This prevents shell injection attacks. Instead, pass params to environment variables and reference them in scripts.

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Passing Parameters to StepActions

Steps provide parameter values to StepActions: 
apiVersion: tekton.dev/v1
kind: Task
metadata:
  name: step-action
spec:
  params:
    - name: param-for-step-action
      description: "this is a param that the step action needs."
  steps:
    - name: action-runner
      ref:
        name: step-action
      params:
        - name: step-action-param
          value: $(params.param-for-step-action)
If a Step declares params for an inlined Step (not referencing a StepAction), it will cause a validation error.

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Parameter Substitution Order

When applying parameters to a StepAction, substitutions occur in this order:
  1. TaskRun parameter values in step parameters
  2. Step-provided parameter values
  3. Default values that reference other parameters
  4. Simple default values
  5. Step result references

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Results

StepActions can declare and emit results.

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Declaring Results

apiVersion: tekton.dev/v1alpha1
kind: StepAction
metadata:
  name: stepaction-declaring-results
spec:
  results:
    - name: current-date-unix-timestamp
      description: The current date in unix timestamp format
    - name: current-date-human-readable
      description: The current date in human readable format
  image: bash:latest
  script: |
    #!/usr/bin/env bash
    date +%s | tee $(step.results.current-date-unix-timestamp.path)
    date | tee $(step.results.current-date-human-readable.path)
StepActions should emit results to $(step.results.<resultName>.path) rather than $(results.<resultName>.path) to avoid name collisions when multiple StepActions are used in the same Task.

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Fetching Results from StepActions

Tasks fetch StepAction results using the value field in Task results: 
apiVersion: tekton.dev/v1
kind: Task
metadata:
  name: task-fetching-results
spec:
  results:
    - name: git-url
      description: "url of git repo"
      value: $(steps.git-clone.results.url)
    - name: registry-url
      description: "url of docker registry"
      value: $(steps.kaniko.results.url)
    - name: digest
      description: "digest of the image"
      value: $(steps.kaniko.results.digest)
  steps:
    - name: git-clone
      ref:
        name: clone-step-action
    - name: kaniko
      ref:
        name: kaniko-step-action
Results emitted to $(step.results.<resultName>.path) are not automatically available as TaskRun results. The Task must explicitly fetch them.

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Passing Results Between Steps

Steps can consume results from previous Steps: 
apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  name: step-action-run
spec:
  TaskSpec:
    steps:
      - name: inline-step
        results:
          - name: result1
            type: array
          - name: result2
            type: string
          - name: result3
            type: object
            properties:
              IMAGE_URL:
                type: string
              IMAGE_DIGEST:
                type: string
        image: alpine
        script: |
          echo -n "[\"image1\", \"image2\", \"image3\"]" | tee $(step.results.result1.path)
          echo -n "foo" | tee $(step.results.result2.path)
          echo -n "{\"IMAGE_URL\":\"ar.com\", \"IMAGE_DIGEST\":\"sha234\"}" | tee $(step.results.result3.path)
      - name: action-runner
        ref:
          name: step-action
        params:
          - name: param1
            value: $(steps.inline-step.results.result1[*])
          - name: param2
            value: $(steps.inline-step.results.result2)
          - name: param3
            value: $(steps.inline-step.results.result3[*])

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Result Reference Syntax

Result TypeParameter TypeSyntaxAPI Fields Required
stringstring$(steps.<step-name>.results.<result-name>)stable
arrayarray$(steps.<step-name>.results.<result-name>[*])alpha or beta
arraystring$(steps.<step-name>.results.<result-name>[i])alpha or beta
objectstring$(tasks.<task-name>.results.<result-name>.key)alpha or beta
Whole array results (using star notation) cannot be referenced in script and env. Step results can only be referenced in a Step’s/StepAction’s env, command, and args.

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Working Directory

Declare a working directory for the StepAction: 
apiVersion: tekton.dev/v1alpha1
kind: StepAction
metadata:
  name: example-stepaction-name
spec:
  image: gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/git-init:latest
  workingDir: /workspace
  script: |
    # clone the repo

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Parameterizing Working Directory

Make the working directory configurable: 
apiVersion: tekton.dev/v1alpha1
kind: StepAction
metadata:
  name: example-stepaction-name
spec:
  image: ubuntu
  params:
    - name: source
      description: "The path to the source code."
  workingDir: $(params.source)

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Security Context

Specify a security context for the StepAction: 
apiVersion: tekton.dev/v1alpha1
kind: StepAction
metadata:
  name: example-stepaction-name
spec:
  image: gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/git-init:latest
  securityContext:
      runAsUser: 0
  script: |
    # clone the repo
The securityContext from StepAction will overwrite the securityContext from TaskRun.

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Volume Mounts

Define volume mounts in StepActions. The volume mount name MUST be a single parameter reference: 
apiVersion: tekton.dev/v1alpha1
kind: StepAction
metadata:
  name: myStep
spec:
  params:
    - name: registryConfig
    - name: otherConfig
  volumeMounts:
    - name: $(params.registryConfig)
      mountPath: /registry-config
    - name: $(params.otherConfig)
      mountPath: /other-config
  image: ...
  script: ...
Valid: $(params.registryConfig) Invalid: $(params.registryConfig)-foo or "unparametrized-name"

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Description

Add a user-facing description: 
apiVersion: tekton.dev/v1
kind: StepAction
metadata:
  name: myStep
spec:
  description: my step
  params: ...
  volumeMounts: ...
  image: ...
  script: ...

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Referencing StepActions

Reference StepActions from Steps using the ref field: 
apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  name: step-action-run
spec:
  taskSpec:
    steps:
      - name: action-runner
        ref:
          name: step-action

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Field Restrictions

When a Step references a StepAction, it CANNOT contain:
  • image
  • command
  • args
  • script
  • env
  • volumeMounts
# This will cause a validation error
apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  name: step-action-run
spec:
  taskSpec:
    steps:
      - name: action-runner
        ref:
          name: step-action
        image: ubuntu  # ERROR: cannot use image with ref

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Allowed Fields with Ref

When referencing a StepAction, a Step CAN contain:
  • computeResources
  • workspaces (Isolated workspaces)
  • volumeDevices
  • imagePullPolicy
  • onError
  • stdoutConfig
  • stderrConfig
  • securityContext
  • envFrom
  • timeout
  • ref
  • params
apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  name: step-action-run
spec:
  taskSpec:
    steps:
      - name: action-runner
        ref:
          name: step-action
        params:
          - name: step-action-param
            value: hello
        computeResources:
          requests:
            memory: 1Gi
            cpu: 500m
        timeout: 1h
        onError: continue

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Remote StepActions

Reference StepActions from remote locations like Git repositories: 
apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  generateName: step-action-run-
spec:
  taskSpec:
    steps:
      - name: action-runner
        ref:
          resolver: git
          params:
            - name: url
              value: https://github.com/repo/repo.git
            - name: revision
              value: main
            - name: pathInRepo
              value: remote_step.yaml
Support for remote resolvers depends on what Resolvers your cluster operator has installed. The default resolver type can be configured using the default-resolver-type field in the config-defaults ConfigMap (alpha feature).

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