Allow Resources to be Optional

Task inputs and outputs are considered required, there is no way today to mark them optional. This change introduce a new field called optional as part of the PipelineResourceDeclaration by default a resource is required. To mark any resource optional, set optional to true: apiVersion: tekton.dev/v1alpha1 kind: Task metadata: name: task-check-workspace spec: inputs: resources: - name: workspace type: git optional: true steps: - name: check-workspace
tektoncd · Dec 13, 2019 · ccacb0c · ccacb0c
1 parent 5830188
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diff --git a/docs/resources.md b/docs/resources.md
@@ -16,6 +16,12 @@ For example:
 --------------------------------------------------------------------------------
 
 -   [Syntax](#syntax)
+-   [Using Resources](#using-resources)
+    - [Variable substitution](#variable-substitution)
+    - [Controlling where resources are mounted](#controlling-where-resources-are-mounted)
+    - [Overriding where resources are copied from](#overriding-where-resources-are-copied-from)
+    - [Resource Status](#resource-status)
+    - [Optional Resources](#optional-resources)
 -   [Resource types](#resource-types)
     -   [Git Resource](#git-resource)
     -   [Pull Request Resource](#pull-request-resource)
@@ -25,7 +31,6 @@ For example:
         -   [GCS Storage Resource](#gcs-storage-resource)
         -   [BuildGCS Storage Resource](#buildgcs-storage-resource)
     -   [Cloud Event Resource](#cloud-event-resource)
--   [Using Resources](#using-resources)
 
 ## Syntax
 
@@ -46,6 +51,8 @@ following fields:
 -   Optional:
     -   [`params`](#resource-types) - Parameters which are specific to each type
         of `PipelineResource`
+    -   [`optional`](#optional-resources) - Boolean flag to mark a resource optional
+        (by default, `optional` is set to `false` making resources mandatory).
 
 [kubernetes-overview]:
   https://kubernetes.io/docs/concepts/overview/working-with-objects/kubernetes-objects/#required-fields
@@ -218,6 +225,30 @@ resourcesResult:
     name: skaffold-image-leeroy-web
 ```
 
+### Optional Resources
+
+By default, a resource is declared as mandatory unless `optional` is set `true` for that resource.
+Resources declared as `optional` in a `Task` does not have be specified in `TaskRun`.
+
+```yaml
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+  name: task-check-optional-resources
+spec:
+  inputs:
+    resources:
+      - name: git-repo
+        type: git
+        optional: true
+```
+
+You can refer to different examples demonstrating usage of optional resources in `Task` and `Condition`:
+
+- [Task](../examples/taskruns/optional-resources.yaml)
+- [Cluster Task](../examples/taskruns/optional-resources-with-clustertask.yaml)
+- [Condition](../examples/pipelineruns/conditional-pipelinerun-with-optional-resources.yaml)
+
 ## Resource Types
 
 ### Git Resource

diff --git a/examples/pipelineruns/conditional-pipelinerun-with-optional-resources.yaml b/examples/pipelineruns/conditional-pipelinerun-with-optional-resources.yaml
@@ -0,0 +1,88 @@
+apiVersion: tekton.dev/v1alpha1
+kind: Condition
+metadata:
+  name: verify-no-file-exists-without-resource
+spec:
+  params:
+    - name: "path"
+  resources:
+    - name: optional-workspace
+      type: git
+      optional: true
+  check:
+    image: alpine
+    command: ["/bin/sh"]
+    args: ['-c', 'test ! -f $(resources.optional-workspace.path)/$(params.path)']
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineResource
+metadata:
+  name: pipeline-git-repo
+spec:
+  type: git
+  params:
+    - name: revision
+      value: master
+    - name: url
+      value: https://github.com/tektoncd/pipeline
+---
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+  name: list-pipeline-repo-files
+spec:
+  inputs:
+    resources:
+      - name: optional-workspace
+        type: git
+        optional: true
+  steps:
+    - name: run-ls
+      image: ubuntu
+      script: |
+        #!/usr/bin/env bash
+        ls -al $(inputs.resources.optional-workspace.path)
+---
+apiVersion: tekton.dev/v1alpha1
+kind: Pipeline
+metadata:
+  name: pipeline-list-pipeline-repo-files
+spec:
+  resources:
+    - name: pipeline-source-repo
+      type: git
+  params:
+    - name: "path"
+      default: "README.md"
+  tasks:
+    - name: list-pipeline-repo-files-1
+      taskRef:
+        name: list-pipeline-repo-files
+      conditions:
+        - conditionRef: "verify-no-file-exists-without-resource"
+          params:
+            - name: "path"
+              value: "$(params.path)"
+# NOTE: Resource "optional-workspace" is declared as optional in Condition
+# No resource specified for the condition here since its optional
+# "DO NOT UNCOMMENT THE FOLLOWING RESOURCE"
+#          resources:
+#            - name: optional-workspace
+#              resource: pipeline-source-repo
+      resources:
+        inputs:
+          - name: optional-workspace
+            resource: pipeline-source-repo
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineRun
+metadata:
+  name: demo-condtional-pr-without-condition-resource
+spec:
+  pipelineRef:
+    name: pipeline-list-pipeline-repo-files
+  serviceAccountName: 'default'
+  resources:
+    - name: pipeline-source-repo
+      resourceRef:
+        name: pipeline-git-repo
diff --git a/examples/taskruns/optional-resources-with-clustertask.yaml b/examples/taskruns/optional-resources-with-clustertask.yaml
@@ -0,0 +1,35 @@
+apiVersion: tekton.dev/v1alpha1
+kind: ClusterTask
+metadata:
+  name: clustertask-with-optional-resources
+spec:
+  inputs:
+    resources:
+      - name: git-repo
+        type: git
+        optional: true
+    params:
+      - name: filename
+        type: string
+        default: "README.md"
+  outputs:
+    resources:
+      - name: optionalimage
+        type: image
+        optional: true
+  steps:
+    - name: task-echo-success
+      image: ubuntu
+      script: |
+        #!/usr/bin/env bash
+        echo "success"
+---
+
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: clustertask-without-resources
+spec:
+  taskRef:
+    name: clustertask-with-optional-resources
+    kind: ClusterTask
diff --git a/examples/taskruns/optional-resources.yaml b/examples/taskruns/optional-resources.yaml
@@ -0,0 +1,131 @@
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+  name: task-check-optional-resources
+spec:
+  inputs:
+    resources:
+      - name: git-repo
+        type: git
+        optional: true
+    params:
+      - name: filename
+        type: string
+        default: "README.md"
+  outputs:
+    resources:
+      - name: optionalimage
+        type: image
+        optional: true
+  steps:
+    - name: check-git-repo
+      image: ubuntu
+      script: |
+        #!/usr/bin/env bash
+        if [ -d $(inputs.resources.git-repo.path) ]; then
+          echo "Git repo was cloned at $(inputs.resources.git-repo.path)"
+          if [ -f $(inputs.resources.git-repo.path)/$(inputs.params.filename) ]; then
+            echo "$(inputs.params.filename) does exist at $(inputs.resources.git-repo.path)"
+          else
+            echo "$(inputs.params.filename) does not exist at $(inputs.resources.git-repo.path)"
+          fi
+        else
+          echo "Git repo was not cloned at $(inputs.resources.git-repo.path)"
+        fi
+        if [ "$(outputs.resources.optionalimage.url)" == "" ]; then
+          echo "Image URL: $(outputs.resources.optionalimage.url)"
+        else
+          echo "No image URL specified."
+        fi
+        echo "Yay, Input and Output Resources can be Optional!"
+---
+
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: demo-optional-inputs-resources-with-resources
+spec:
+  inputs:
+    resources:
+      - name: git-repo
+        resourceSpec:
+          type: git
+          params:
+            - name: url
+              value: https://github.com/tektoncd/pipeline.git
+    params:
+      - name: filename
+        value: "README.md"
+  outputs:
+    resources:
+      - name: optionalimage
+        resourceSpec:
+          type: image
+          params:
+            - name: url
+              value: gcr.io/foo/bar
+  taskRef:
+    name: task-check-optional-resources
+---
+
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: demo-optional-inputs-resources-invalid-filename
+spec:
+  inputs:
+    resources:
+      - name: git-repo
+        resourceSpec:
+          type: git
+          params:
+            - name: url
+              value: https://github.com/tektoncd/pipeline.git
+    params:
+      - name: filename
+        value: "invalid.md"
+  taskRef:
+    name: task-check-optional-resources
+---
+
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: demo-optional-inputs-resources-without-resources
+spec:
+  inputs:
+    params:
+      - name: filename
+        value: "README.md"
+  taskRef:
+    name: task-check-optional-resources
+---
+
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: demo-optional-inputs-resources-without-resources-and-params
+spec:
+  taskRef:
+    name: task-check-optional-resources
+---
+
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: demo-optional-outputs-resources-with-input-resources
+spec:
+  inputs:
+    resources:
+      - name: git-repo
+        resourceSpec:
+          type: git
+          params:
+            - name: url
+              value: https://github.com/tektoncd/pipeline.git
+    params:
+      - name: filename
+        value: "README.md"
+  taskRef:
+    name: task-check-optional-resources
+---
diff --git a/pkg/apis/pipeline/v1alpha1/resource_types.go b/pkg/apis/pipeline/v1alpha1/resource_types.go
@@ -209,7 +209,7 @@ type PipelineResourceList struct {
 type ResourceDeclaration = v1alpha2.ResourceDeclaration
 
 // ResourceFromType returns an instance of the correct PipelineResource object type which can be
-// used to add input and ouput containers as well as volumes to a TaskRun's pod in order to realize
+// used to add input and output containers as well as volumes to a TaskRun's pod in order to realize
 // a PipelineResource in a pod.
 func ResourceFromType(r *PipelineResource, images pipeline.Images) (PipelineResourceInterface, error) {
 	switch r.Spec.Type {

diff --git a/pkg/apis/pipeline/v1alpha1/task_validation_test.go b/pkg/apis/pipeline/v1alpha1/task_validation_test.go
@@ -49,6 +49,22 @@ var invalidResource = v1alpha1.TaskResource{
 	},
 }
 
+var optionalResource = v1alpha1.TaskResource{
+	ResourceDeclaration: v1alpha1.ResourceDeclaration{
+		Name:     "source",
+		Type:     "git",
+		Optional: true,
+	},
+}
+
+var requiredResource = v1alpha1.TaskResource{
+	ResourceDeclaration: v1alpha1.ResourceDeclaration{
+		Name:     "source",
+		Type:     "git",
+		Optional: false,
+	},
+}
+
 var validSteps = []v1alpha1.Step{{Container: corev1.Container{
 	Name:  "mystep",
 	Image: "myimage",
@@ -105,6 +121,22 @@ func TestTaskSpecValidate(t *testing.T) {
 			},
 			Steps: validSteps,
 		},
+	}, {
+		name: "valid inputs (required)",
+		fields: fields{
+			Inputs: &v1alpha1.Inputs{
+				Resources: []v1alpha1.TaskResource{requiredResource},
+			},
+			Steps: validSteps,
+		},
+	}, {
+		name: "valid inputs (optional)",
+		fields: fields{
+			Inputs: &v1alpha1.Inputs{
+				Resources: []v1alpha1.TaskResource{optionalResource},
+			},
+			Steps: validSteps,
+		},
 	}, {
 		name: "valid outputs",
 		fields: fields{
@@ -135,6 +167,22 @@ func TestTaskSpecValidate(t *testing.T) {
 			},
 			Steps: validSteps,
 		},
+	}, {
+		name: "valid outputs (required)",
+		fields: fields{
+			Inputs: &v1alpha1.Inputs{
+				Resources: []v1alpha1.TaskResource{requiredResource},
+			},
+			Steps: validSteps,
+		},
+	}, {
+		name: "valid outputs (optional)",
+		fields: fields{
+			Inputs: &v1alpha1.Inputs{
+				Resources: []v1alpha1.TaskResource{optionalResource},
+			},
+			Steps: validSteps,
+		},
 	}, {
 		name: "valid template variable",
 		fields: fields{