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
- refactor image exporter code and add more unit tests

cmd/imagedigestexporter/main.go

@@ -31,6 +31,13 @@ var (
 	images = flag.String("images", "", "List of images resources built by task in json format")
 )
 
+/* The input of this go program will be a JSON string with all the output PipelineResources of type
+Image, which will include the path to where the index.json file will be located. The program will
+read the related index.json file(s) and log another JSON string including the name of the image resource
+and the digests.
+The input is an array of ImageResource, ex: [{"name":"srcimg1","type":"image","url":"gcr.io/some-image-1","digest":"","OutputImagePath":"/path/image"}]
+The output is an array of PipelineResourceResult, ex: [{"name":"image","digest":"sha256:eed29..660"}]
+*/
 func main() {
 	flag.Parse()
 
@@ -42,7 +49,7 @@ 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

docs/resources.md

@@ -164,10 +164,55 @@ spec:
 
 #### Surfacing the image digest built in a task
 
-To surface the image digest in the output of the `taskRun` the builder tool should produce this information in a [oci-layout-image](https://github.com/opencontainers/image-spec/blob/master/image-layout.md) `index.json` file. This file should be placed on a location as specified in 
-the image resource `indexpath`. 
+To surface the image digest in the output of the `taskRun` the builder tool should produce this information in a [oci-layout-image](https://github.com/opencontainers/image-spec/blob/master/image-layout.md) `index.json` file. This file should be placed on a location as specified in the task definition under the resource `outputImagePath`
 
-The `taskRun` will include the image digest in the `resourcesResult` field that is part of the taskRun.Status. 
+for example this build-push task defines the `outputImagePath` for the `buildImage` resource in `/worksapce/buildImage`
+```yaml
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+  name: build-push
+spec:
+  inputs:
+    resources:
+    - name: workspace
+      type: git
+  outputs:
+    resources:
+    - name: builtImage
+      type: image
+      outputImagePath: /workspace/builtImage
+  steps: ...
+```
+If no value is specified for `outputImagePath`, it will default to `/tools/image-outputs/{resource-name}`.
+
+*Please check the builder tool used on how to pass this path to create the output file.*  
+
+The `taskRun` will include the image digest in the `resourcesResult` field that is part of the `taskRun.Status` 
+
+for example:
+
+```yaml
+status:
+    completionTime: 2019-04-29T14:20:41Z
+    conditions:
+    - lastTransitionTime: 2019-04-29T14:20:41Z
+      status: "True"
+      type: Succeeded
+    podName: build-push-run-pod-0a1777
+    resourcesResult:
+    - digest: sha256:eed29cd0b6feeb1a92bc3c4f977fd203c63b376a638731c88cacefe3adb1c660
+      name: skaffold-image-leeroy-web
+    startTime: 2019-04-29T14:20:30Z
+    steps:
+    - name: build-and-push
+      terminated:
+        containerID: docker://140fbe0d923bd0196e0ef1edbf088731ff1e8d37bfa9b04307701ccbdae77426
+        exitCode: 0
+        finishedAt: 2019-04-29T14:20:39Z
+        reason: Completed
+        startedAt: 2019-04-29T14:20:36Z
+```
 
 If the `index.json` file is not produced, the image digest will not be included in the `taskRun` output.
 

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)
 			}
 		})