enhancements for the exporting output image digest

 - use pod termination message to export the image digest instead of logs
 - add more logs when index.json is not found
 - create a container to create the default folder for image output digest dir

cmd/imagedigestexporter/main.go

@@ -19,8 +19,8 @@ package main
 import (
 	"encoding/json"
 	"flag"
-	"fmt"
 	"log"
+	"os"
 
 	"github.com/google/go-containerregistry/pkg/v1/layout"
 	v1alpha1 "github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1"
@@ -41,8 +41,7 @@ func main() {
 	flag.Parse()
 
 	imageResources := []*v1alpha1.ImageResource{}
-	err := json.Unmarshal([]byte(*images), &imageResources)
-	if err != nil {
+	if err := json.Unmarshal([]byte(*images), &imageResources); err != nil {
 		log.Fatalf("Error reading images array: %v", err)
 	}
 
@@ -52,6 +51,7 @@ func main() {
 		if err != nil {
 			// if this image doesn't have a builder that supports index.json file,
 			// then it will be skipped
+			log.Printf("ImageResource %s doesn't have an index.json file: %s", imageResource.Name, err)
 			continue
 		}
 		digest, err := ii.Digest()
@@ -65,5 +65,18 @@ func main() {
 	if err != nil {
 		log.Fatalf("Unexpected error converting images to json %v: %v", output, err)
 	}
-	fmt.Println(string(imagesJSON))
+	log.Printf("Image digest exporter output: %s ", string(imagesJSON))
+	f, err := os.OpenFile("/workspace/builder/termination-log", os.O_WRONLY|os.O_CREATE, 0666)
+	if err != nil {
+		log.Fatalf("Unexpected error converting images to json %v: %v", output, err)
+	}
+	defer f.Close()
+
+	_, err = f.Write(imagesJSON)
+	if err != nil {
+		log.Fatalf("Unexpected error converting images to json %v: %v", output, err)
+	}
+	if err := f.Sync(); err != nil {
+		log.Fatalf("Unexpected error converting images to json %v: %v", output, err)
+	}
 }

docs/resources.md

@@ -291,7 +291,7 @@ spec:
 ```
 
 If no value is specified for `outputImageDir`, it will default to
-`/builder/image-outputs/{resource-name}`.
+`/builder/home/image-outputs/{resource-name}`.
 
 _Please check the builder tool used on how to pass this path to create the
 output file._

examples/taskruns/task-multiple-output-image.yaml

@@ -0,0 +1,128 @@
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineResource
+metadata:
+  name: skaffold-image-leeroy-web-1
+spec:
+  type: image
+  params:
+  - name: url
+    value: gcr.io/christiewilson-catfactory/leeroy-web # Replace this URL with ${KO_DOCKER_REPO}
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineResource
+metadata:
+  name: skaffold-image-leeroy-web-2
+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: multiple-build-push-kaniko
+spec:
+  inputs:
+    resources:
+    - name: sourcerepo
+      type: git
+  outputs:
+    resources:
+    - name: builtImage1
+      type: image
+    - name: builtImage2
+      type: image
+  steps:
+  - name: build-and-push-1
+    image: busybox
+    command:
+    - /bin/sh
+    args:
+    - -ce
+    - |
+      set -ex
+      cat <<EOF > /builder/home/image-outputs/builtImage1/index.json
+      {
+        "schemaVersion": 2,
+        "manifests": [
+          {
+            "mediaType": "application/vnd.oci.image.index.v1+json",
+            "size": 314,
+            "digest": "sha256:05f95b26ed10668b7183c1e2da98610e91372fa9f510046d4ce5812addad86b5"
+          }
+        ]
+      }
+      EOF
+  - name: build-and-push-2
+    image: busybox
+    command:
+    - /bin/sh
+    args:
+    - -ce
+    - |
+      set -e
+      cat <<EOF > /builder/home/image-outputs/builtImage2/index.json
+      {
+        "schemaVersion": 2,
+        "manifests": [
+          {
+            "mediaType": "application/vnd.oci.image.index.v1+json",
+            "size": 314,
+            "digest": "sha256:05f95b26ed10668b7183c1e2da98610e91372fa9f510046d4ce5812addad86b5"
+          }
+        ]
+      }
+      EOF         
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: multiple-build-push-kaniko-run
+spec:
+  taskRef:
+    name: multiple-build-push-kaniko
+  trigger:
+    type: manual
+  inputs:
+    resources:
+    - name: sourcerepo
+      resourceRef:
+        name: skaffold-git
+  outputs:
+    resources:
+    - name: builtImage1
+      resourceRef:
+        name: skaffold-image-leeroy-web-1
+    - name: builtImage2
+      resourceRef:
+        name: skaffold-image-leeroy-web-2

pkg/apis/pipeline/v1alpha1/task_defaults.go

@@ -31,7 +31,7 @@ func (ts *TaskSpec) SetDefaults(ctx context.Context) {
 		for i, o := range ts.Outputs.Resources {
 			if o.Type == PipelineResourceTypeImage {
 				if o.OutputImageDir == "" {
-					ts.Outputs.Resources[i].OutputImageDir = fmt.Sprintf("/builder/image-outputs/%s", o.Name)
+					ts.Outputs.Resources[i].OutputImageDir = fmt.Sprintf("%s/%s", TaskOutputImageDefaultDir, o.Name)
 				}
 			}
 		}

pkg/apis/pipeline/v1alpha1/task_types.go

@@ -67,6 +67,11 @@ type TaskSpec struct {
 var _ apis.Validatable = (*Task)(nil)
 var _ apis.Defaultable = (*Task)(nil)
 
+const (
+	// TaskOutputImageDefaultDir is the default directory for output image resource,
+	TaskOutputImageDefaultDir = "/builder/home/image-outputs"
+)
+
 // +genclient
 // +genclient:noStatus
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

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

@@ -80,12 +80,13 @@ func AddOutputImageDigestExporter(
 
 			taskSpec.Steps = augmentedSteps
 		}
+
 	}
 
 	return nil
 }
 
-// UpdateTaskRunStatusWithResourceResult if there an update to the outout image resource, add to taskrun status result
+// UpdateTaskRunStatusWithResourceResult if there is an update to the outout image resource, add to taskrun status result
 func UpdateTaskRunStatusWithResourceResult(taskRun *v1alpha1.TaskRun, logContent []byte) error {
 	err := json.Unmarshal(logContent, &taskRun.Status.ResourcesResult)
 	if err != nil {
@@ -102,6 +103,8 @@ func imageDigestExporterContainer(stepName string, imagesJSON []byte) corev1.Con
 		Args: []string{
 			"-images", string(imagesJSON),
 		},
+		TerminationMessagePath:   "/workspace/builder/termination-log",
+		TerminationMessagePolicy: corev1.TerminationMessageFallbackToLogsOnError,
 	}
 }
 

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

@@ -93,6 +93,8 @@ func TestAddOutputImageDigestExporter(t *testing.T) {
 				Image:   "override-with-imagedigest-exporter-image:latest",
 				Command: []string{"/ko-app/imagedigestexporter"},
 				Args:    []string{"-images", fmt.Sprintf("[{\"name\":\"source-image-1\",\"type\":\"image\",\"url\":\"gcr.io/some-image-1\",\"digest\":\"\",\"OutputImageDir\":\"%s\"}]", currentDir)},
+				TerminationMessagePath:   "/workspace/builder/termination-log",
+				TerminationMessagePolicy: "FallbackToLogsOnError",
 			}},
 	}, {
 		desc: "image resource in task with multiple steps",
@@ -155,13 +157,17 @@ func TestAddOutputImageDigestExporter(t *testing.T) {
 				Image:   "override-with-imagedigest-exporter-image:latest",
 				Command: []string{"/ko-app/imagedigestexporter"},
 				Args:    []string{"-images", fmt.Sprintf("[{\"name\":\"source-image-1\",\"type\":\"image\",\"url\":\"gcr.io/some-image-1\",\"digest\":\"\",\"OutputImageDir\":\"%s\"}]", currentDir)},
+				TerminationMessagePath:   "/workspace/builder/termination-log",
+				TerminationMessagePolicy: "FallbackToLogsOnError",
 			}, {
 				Name: "step2",
 			}, {
 				Name:    "image-digest-exporter-step2-mz4c7",
 				Image:   "override-with-imagedigest-exporter-image:latest",
 				Command: []string{"/ko-app/imagedigestexporter"},
 				Args:    []string{"-images", fmt.Sprintf("[{\"name\":\"source-image-1\",\"type\":\"image\",\"url\":\"gcr.io/some-image-1\",\"digest\":\"\",\"OutputImageDir\":\"%s\"}]", currentDir)},
+				TerminationMessagePath:   "/workspace/builder/termination-log",
+				TerminationMessagePolicy: "FallbackToLogsOnError",
 			},
 		},
 	}} {

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

@@ -208,6 +208,26 @@ func makeWorkingDirInitializer(steps []corev1.Container) *corev1.Container {
 	return nil
 }
 
+// initOutputResourcesDefaultDir checks if there are any output image resources expecting a default path
+// and creates an init container to create that folder
+func initOutputResourcesDefaultDir(taskRun *v1alpha1.TaskRun, taskSpec v1alpha1.TaskSpec) []corev1.Container {
+	makeDirSteps := []corev1.Container{}
+	if len(taskRun.Spec.Outputs.Resources) > 0 {
+		for _, r := range taskRun.Spec.Outputs.Resources {
+			for _, o := range taskSpec.Outputs.Resources {
+				if o.Name == r.Name {
+					if strings.HasPrefix(o.OutputImageDir, v1alpha1.TaskOutputImageDefaultDir) {
+						cn := v1alpha1.CreateDirContainer("default-image-output", fmt.Sprintf("%s/%s", v1alpha1.TaskOutputImageDefaultDir, r.Name))
+						cn.VolumeMounts = append(cn.VolumeMounts, implicitVolumeMounts...)
+						makeDirSteps = append(makeDirSteps, cn)
+					}
+				}
+			}
+		}
+	}
+	return makeDirSteps
+}
+
 // GetPod returns the Pod for the given pod name
 type GetPod func(string, metav1.GetOptions) (*corev1.Pod, error)
 
@@ -239,6 +259,8 @@ func MakePod(taskRun *v1alpha1.TaskRun, taskSpec v1alpha1.TaskSpec, kubeclient k
 		initContainers = append(initContainers, *workingDir)
 	}
 
+	initContainers = append(initContainers, initOutputResourcesDefaultDir(taskRun, taskSpec)...)
+
 	maxIndicesByResource := findMaxResourceRequest(taskSpec.Steps, corev1.ResourceCPU, corev1.ResourceMemory, corev1.ResourceEphemeralStorage)
 
 	for i := range taskSpec.Steps {