updates to pr #721

- run the image digest exporter after each step
- move the index path to the task definition instead of the resource since the user needs to know this at the time of creating the task so it can be used as part of the steps scripting if needed
- rename indexpath to outputimagepath
- add example yaml

cmd/imagedigestexporter/main.go

@@ -42,7 +42,7 @@ func main() {
 
 	output := []v1alpha1.PipelineResourceResult{}
 	for _, imageResource := range imageResources {
-		ii, err := layout.ImageIndexFromPath(imageResource.IndexPath)
+		ii, err := layout.ImageIndexFromPath(imageResource.OutputImagePath)
 		if err != nil {
 			// if this image doesn't have a builder that supports index.josn file,
 			// then it will be skipped

examples/taskruns/task-output-image.yaml

@@ -0,0 +1,103 @@
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineResource
+metadata:
+  name: skaffold-image-leeroy-web
+spec:
+  type: image
+  params:
+  - name: url
+    value: gcr.io/christiewilson-catfactory/leeroy-web # Replace this URL with ${KO_DOCKER_REPO}
+---
+# This demo modifies the cluster (deploys to it) you must use a service
+# account with permission to admin the cluster (or make your default user an admin
+# of the `default` namespace with default-cluster-admin.
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: default-cluster-admin
+subjects:
+  - kind: ServiceAccount
+    name: default
+    namespace: default
+roleRef:
+  kind: ClusterRole
+  name: cluster-admin
+  apiGroup: rbac.authorization.k8s.io
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineResource
+metadata:
+  name: skaffold-git
+spec:
+  type: git
+  params:
+  - name: revision
+    value: master
+  - name: url
+    value: https://github.com/GoogleContainerTools/skaffold
+---
+#Builds an image via kaniko and pushes it to registry.
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+  name: build-push-kaniko
+spec:
+  inputs:
+    resources:
+    - name: workspace
+      type: git
+  outputs:
+    resources:
+    - name: builtImage
+      type: image
+      outputImagePath: /workspace/workspace
+  steps:
+  - name: build-and-push
+    image: busybox
+    command:
+    - /bin/sh
+    args:
+    - -ce
+    - |
+      set -e
+      cat <<EOF > /workspace/workspace/index.json
+      {
+        "schemaVersion": 2,
+        "manifests": [
+          {
+            "mediaType": "application/vnd.oci.image.index.v1+json",
+            "size": 314,
+            "digest": "sha256:05f95b26ed10668b7183c1e2da98610e91372fa9f510046d4ce5812addad86b5"
+          }
+        ]
+      }
+      EOF
+  - name: echo
+    image: busybox
+    command:
+    - /bin/sh
+    args:
+    - -ce
+    - |
+      set -e
+      cat /workspace/workspace/index.json
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: build-push-run
+spec:
+  taskRef:
+    name: build-push-kaniko
+  trigger:
+    type: manual
+  inputs:
+    resources:
+    - name: workspace
+      resourceRef:
+        name: skaffold-git
+  outputs:
+    resources:
+    - name: builtImage
+      resourceRef:
+        name: skaffold-image-leeroy-web

pkg/apis/pipeline/v1alpha1/image_resource.go

@@ -40,8 +40,6 @@ func NewImageResource(r *PipelineResource) (*ImageResource, error) {
 			ir.URL = param.Value
 		case strings.EqualFold(param.Name, "Digest"):
 			ir.Digest = param.Value
-		case strings.EqualFold(param.Name, "IndexPath"):
-			ir.IndexPath = param.Value
 		}
 	}
 
@@ -50,11 +48,11 @@ func NewImageResource(r *PipelineResource) (*ImageResource, error) {
 
 // ImageResource defines an endpoint where artifacts can be stored, such as images.
 type ImageResource struct {
-	Name      string               `json:"name"`
-	Type      PipelineResourceType `json:"type"`
-	URL       string               `json:"url"`
-	Digest    string               `json:"digest"`
-	IndexPath string               `json:"indexpath"`
+	Name            string               `json:"name"`
+	Type            PipelineResourceType `json:"type"`
+	URL             string               `json:"url"`
+	Digest          string               `json:"digest"`
+	OutputImagePath string
 }
 
 // GetName returns the name of the resource
@@ -73,11 +71,10 @@ func (s ImageResource) GetParams() []Param { return []Param{} }
 // Replacements is used for template replacement on an ImageResource inside of a Taskrun.
 func (s *ImageResource) Replacements() map[string]string {
 	return map[string]string{
-		"name":      s.Name,
-		"type":      string(s.Type),
-		"url":       s.URL,
-		"digest":    s.Digest,
-		"indexpath": s.IndexPath,
+		"name":   s.Name,
+		"type":   string(s.Type),
+		"url":    s.URL,
+		"digest": s.Digest,
 	}
 }
 
@@ -95,9 +92,9 @@ func (s *ImageResource) GetDownloadContainerSpec() ([]corev1.Container, error) {
 func (s *ImageResource) SetDestinationDirectory(path string) {
 }
 
-// GetIndexPath return the path to get the index.json file
-func (s *ImageResource) GetIndexPath() string {
-	return s.IndexPath
+// GetOutputImagePath return the path to get the index.json file
+func (s *ImageResource) GetOutputImagePath() string {
+	return s.OutputImagePath
 }
 
 func (s ImageResource) String() string {

pkg/apis/pipeline/v1alpha1/resource_types.go

@@ -94,7 +94,9 @@ type TaskResource struct {
 	// +optional
 	// TargetPath is the path in workspace directory where the task resource will be copied.
 	TargetPath string `json:"targetPath"`
-	// Resource Value stuff
+	// +optional
+	// Path to the index.json file for output container images
+	OutputImagePath string `json:"outputImagePath"`
 }
 
 // +genclient

pkg/apis/pipeline/v1alpha1/task_defaults.go

@@ -16,12 +16,25 @@ limitations under the License.
 
 package v1alpha1
 
-import "context"
+import (
+	"context"
+	"fmt"
+)
 
 func (t *Task) SetDefaults(ctx context.Context) {
 	t.Spec.SetDefaults(ctx)
 }
 
+// SetDefaults set any defaults for the task spec
 func (ts *TaskSpec) SetDefaults(ctx context.Context) {
+	if ts.Outputs != nil && len(ts.Outputs.Resources) > 0 {
+		for i, o := range ts.Outputs.Resources {
+			if o.Type == PipelineResourceTypeImage {
+				if o.OutputImagePath == "" {
+					ts.Outputs.Resources[i].OutputImagePath = fmt.Sprintf("/tools/image-outputs/%s", o.Name)
+				}
+			}
+		}
+	}
 	return
 }

pkg/apis/pipeline/v1alpha1/task_validation.go

@@ -145,6 +145,11 @@ func validateResourceVariables(steps []corev1.Container, inputs *Inputs, outputs
 	if outputs != nil {
 		for _, r := range outputs.Resources {
 			resourceNames[r.Name] = struct{}{}
+			if r.Type == PipelineResourceTypeImage {
+				if r.OutputImagePath == "" {
+					return apis.ErrMissingField("OutputImagePath")
+				}
+			}
 		}
 	}
 	return validateVariables(steps, "resources", resourceNames)

pkg/apis/pipeline/v1alpha1/task_validation_test.go

@@ -31,6 +31,11 @@ var validResource = TaskResource{
 	Type: "git",
 }
 
+var validImageResource = TaskResource{
+	Name: "source",
+	Type: "image",
+}
+
 var validBuildSteps = []corev1.Container{{
 	Name:  "mystep",
 	Image: "myimage",
@@ -84,6 +89,17 @@ func TestTaskSpecValidate(t *testing.T) {
 			},
 			BuildSteps: validBuildSteps,
 		},
+	}, {
+		name: "output image resoure",
+		fields: fields{
+			Inputs: &Inputs{
+				Resources: []TaskResource{validImageResource},
+			},
+			Outputs: &Outputs{
+				Resources: []TaskResource{validImageResource},
+			},
+			BuildSteps: validBuildSteps,
+		},
 	}, {
 		name: "valid template variable",
 		fields: fields{
@@ -116,7 +132,9 @@ func TestTaskSpecValidate(t *testing.T) {
 				Outputs: tt.fields.Outputs,
 				Steps:   tt.fields.BuildSteps,
 			}
-			if err := ts.Validate(context.Background()); err != nil {
+			ctx := context.Background()
+			ts.SetDefaults(ctx)
+			if err := ts.Validate(ctx); err != nil {
 				t.Errorf("TaskSpec.Validate() = %v", err)
 			}
 		})

pkg/reconciler/v1alpha1/taskrun/resources/image_exporter.go

@@ -19,9 +19,11 @@ package resources
 import (
 	"encoding/json"
 	"flag"
+	"os"
 
 	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1"
 	listers "github.com/tektoncd/pipeline/pkg/client/listers/pipeline/v1alpha1"
+	"github.com/tektoncd/pipeline/pkg/names"
 	"go.uber.org/zap"
 	corev1 "k8s.io/api/core/v1"
 )
@@ -58,28 +60,49 @@ func AddOutputImageDigestExporter(
 					logger.Errorf("Invalid Image Resource for taskRun %q resource %v; error: %s", tr.Name, boundResource, err.Error())
 					return err
 				}
+				for _, o := range taskSpec.Outputs.Resources {
+					if o.Name == boundResource.Name {
+						if o.OutputImagePath != "" {
+							if _, err := os.Stat(o.OutputImagePath); os.IsNotExist(err) {
+								if err := os.MkdirAll(o.OutputImagePath, os.ModePerm); err != nil {
+									return err
+								}
+							}
+							imageResource.OutputImagePath = o.OutputImagePath
+							break
+						}
+					}
+				}
 				output = append(output, imageResource)
 			}
 		}
 
 		if len(output) > 0 {
+			augmentedSteps := []corev1.Container{}
 			imagesJSON, err := json.Marshal(output)
 			if err != nil {
 				return err
 			}
 
-			c := corev1.Container{
-				Name:    "image-digest-exporter",
-				Image:   *imageDigestExporterImage,
-				Command: []string{"/ko-app/imagedigestexporter"},
-				Args: []string{
-					"-images", string(imagesJSON),
-				},
+			for _, s := range taskSpec.Steps {
+				augmentedSteps = append(augmentedSteps, s)
+				augmentedSteps = append(augmentedSteps, imageDigestExporterContainer(s.Name, imagesJSON))
 			}
 
-			taskSpec.Steps = append(taskSpec.Steps, c)
+			taskSpec.Steps = augmentedSteps
 		}
 	}
 
 	return nil
 }
+
+func imageDigestExporterContainer(stepName string, imagesJSON []byte) corev1.Container {
+	return corev1.Container{
+		Name:    names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("image-digest-exporter-" + stepName),
+		Image:   *imageDigestExporterImage,
+		Command: []string{"/ko-app/imagedigestexporter"},
+		Args: []string{
+			"-images", string(imagesJSON),
+		},
+	}
+}