Changes to add results to a task

cmd/entrypoint/main.go

@@ -29,12 +29,12 @@ import (
 )
 
 var (
-	ep              = flag.String("entrypoint", "", "Original specified entrypoint to execute")
-	waitFiles       = flag.String("wait_file", "", "Comma-separated list of paths to wait for")
-	waitFileContent = flag.Bool("wait_file_content", false, "If specified, expect wait_file to have content")
-	postFile        = flag.String("post_file", "", "If specified, file to write upon completion")
-	terminationPath = flag.String("termination_path", "/tekton/termination", "If specified, file to write upon termination")
-
+	ep                  = flag.String("entrypoint", "", "Original specified entrypoint to execute")
+	waitFiles           = flag.String("wait_file", "", "Comma-separated list of paths to wait for")
+	waitFileContent     = flag.Bool("wait_file_content", false, "If specified, expect wait_file to have content")
+	postFile            = flag.String("post_file", "", "If specified, file to write upon completion")
+	terminationPath     = flag.String("termination_path", "/tekton/termination", "If specified, file to write upon termination")
+	results             = flag.String("results", "", "If specified, list of file names that might contain task results")
 	waitPollingInterval = time.Second
 )
 
@@ -51,6 +51,7 @@ func main() {
 		Waiter:          &realWaiter{},
 		Runner:          &realRunner{},
 		PostWriter:      &realPostWriter{},
+		Results:         strings.Split(*results, ","),
 	}
 	if err := e.Go(); err != nil {
 		switch t := err.(type) {

docs/developers/README.md

@@ -185,7 +185,7 @@ There are known issues with the existing implementation of sidecars:
 
 - When the `nop` image does provide the sidecar's command, the sidecar will continue to
 run even after `nop` has been swapped into the sidecar container's image
-field. See https://github.com/tektoncd/pipeline/issues/1347 for the issue
+field. See <https://github.com/tektoncd/pipeline/issues/1347> for the issue
 tracking this bug. Until this issue is resolved the best way to avoid it is to
 avoid overriding the `nop` image when deploying the tekton controller, or
 ensuring that the overridden `nop` image contains as few commands as possible.

pkg/apis/pipeline/paths.go

@@ -19,4 +19,6 @@ package pipeline
 const (
 	// WorkspaceDir is the root directory used for PipelineResources and (by default) Workspaces
 	WorkspaceDir = "/workspace"
+	// DefaultResultPath is the path for task result
+	DefaultResultPath = "/tekton/results"
 )

pkg/apis/pipeline/v1alpha1/resource_types.go

@@ -123,8 +123,12 @@ type PipelineResourceResult struct {
 	Key         string              `json:"key"`
 	Value       string              `json:"value"`
 	ResourceRef PipelineResourceRef `json:"resourceRef,omitempty"`
+	ResultType  ResultType          `json:"type,omitempty"`
 }
 
+// ResultType used to find out whether a PipelineResourceResult is from a task result or not
+type ResultType string
+
 // ResourceFromType returns an instance of the correct PipelineResource object type which can be
 // 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.

pkg/apis/pipeline/v1alpha1/task_types.go

@@ -64,6 +64,18 @@ type TaskSpec struct {
 
 	// Workspaces are the volumes that this Task requires.
 	Workspaces []WorkspaceDeclaration `json:"workspaces,omitempty"`
+
+	// Results are values that this Task can output
+	Results []TaskResult `json:"results,omitempty"`
+}
+
+// TaskResult used to describe the results of a task
+type TaskResult struct {
+	// Name the given name
+	Name string `json:"name"`
+
+	// Description the given description
+	Description string `json:"description"`
 }
 
 // Step embeds the Container type, which allows it to include fields not

pkg/entrypoint/entrypointer.go

@@ -18,8 +18,12 @@ package entrypoint
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"time"
 
+	"github.com/tektoncd/pipeline/pkg/apis/pipeline"
 	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1"
 	"github.com/tektoncd/pipeline/pkg/logging"
 	"github.com/tektoncd/pipeline/pkg/termination"
@@ -51,6 +55,9 @@ type Entrypointer struct {
 	Runner Runner
 	// PostWriter encapsulates writing files when complete.
 	PostWriter PostWriter
+
+	// Results is the set of files that might contain task results
+	Results []string
 }
 
 // Waiter encapsulates waiting for files to exist.
@@ -100,12 +107,44 @@ func (e Entrypointer) Go() error {
 	// Write the post file *no matter what*
 	e.WritePostFile(e.PostFile, err)
 
+	if e.Results != nil {
+		if err := e.readResultsFromDisk(); err != nil {
+			logger.Fatalf("Error while handling results: %s", err)
+		}
+	}
 	if wErr := termination.WriteMessage(e.TerminationPath, output); wErr != nil {
 		logger.Fatalf("Error while writing message: %s", wErr)
 	}
 	return err
 }
 
+func (e Entrypointer) readResultsFromDisk() error {
+	output := []v1alpha1.PipelineResourceResult{}
+	for _, resultFile := range e.Results {
+		// check result file
+		fileContents, err := ioutil.ReadFile(filepath.Join(pipeline.DefaultResultPath, resultFile))
+		if os.IsNotExist(err) {
+			continue
+		} else if err != nil {
+			return err
+		}
+		// if the file doesn't exist, ignore it
+		output = append(output, v1alpha1.PipelineResourceResult{
+			Key:        resultFile,
+			Value:      string(fileContents),
+			ResultType: "result",
+		})
+	}
+	// push output to termination path
+	if len(output) != 0 {
+		if err := termination.WriteMessage(e.TerminationPath, output); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// WritePostFile write the postfile
 func (e Entrypointer) WritePostFile(postFile string, err error) {
 	if err != nil && postFile != "" {
 		postFile = fmt.Sprintf("%s.err", postFile)

pkg/pod/entrypoint.go

@@ -22,6 +22,8 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/tektoncd/pipeline/pkg/apis/pipeline"
+	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
@@ -39,6 +41,8 @@ const (
 	readyAnnotation        = "tekton.dev/ready"
 	readyAnnotationValue   = "READY"
 
+	resultsVolumeName = "tekton-internal-results"
+
 	stepPrefix    = "step-"
 	sidecarPrefix = "sidecar-"
 )
@@ -54,6 +58,15 @@ var (
 		VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}},
 	}
 
+	resultsMount = corev1.VolumeMount{
+		Name:      resultsVolumeName,
+		MountPath: pipeline.DefaultResultPath,
+	}
+	resultsVolume = corev1.Volume{
+		Name:         resultsVolumeName,
+		VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}},
+	}
+
 	// TODO(#1605): Signal sidecar readiness by injecting entrypoint,
 	// remove dependency on Downward API.
 	downwardVolume = corev1.Volume{
@@ -85,16 +98,26 @@ var (
 // method, using entrypoint_lookup.go.
 //
 // TODO(#1605): Also use entrypoint injection to order sidecar start/stop.
-func orderContainers(entrypointImage string, steps []corev1.Container) (corev1.Container, []corev1.Container, error) {
-	toolsInit := corev1.Container{
+func orderContainers(images pipeline.Images, steps []corev1.Container, results []v1alpha1.TaskResult) ([]corev1.Container, []corev1.Container, error) {
+	initContainers := []corev1.Container{}
+	if results != nil && len(results) != 0 {
+		initContainers = append(initContainers, corev1.Container{
+			Name:         "results-dir-initializer",
+			Image:        images.ShellImage,
+			Command:      []string{"sh"},
+			Args:         []string{"-c", "mkdir -p " + pipeline.DefaultResultPath},
+			VolumeMounts: []corev1.VolumeMount{resultsMount},
+		})
+	}
+	initContainers = append(initContainers, corev1.Container{
 		Name:         "place-tools",
-		Image:        entrypointImage,
+		Image:        images.EntrypointImage,
 		Command:      []string{"cp", "/ko-app/entrypoint", entrypointBinary},
 		VolumeMounts: []corev1.VolumeMount{toolsMount},
-	}
+	})
 
 	if len(steps) == 0 {
-		return corev1.Container{}, nil, errors.New("No steps specified")
+		return []corev1.Container{}, nil, errors.New("No steps specified")
 	}
 
 	for i, s := range steps {
@@ -117,10 +140,11 @@ func orderContainers(entrypointImage string, steps []corev1.Container) (corev1.C
 				"-termination_path", terminationPath,
 			}
 		}
+		argsForEntrypoint = append(argsForEntrypoint, resultArgument(steps, results)...)
 
 		cmd, args := s.Command, s.Args
 		if len(cmd) == 0 {
-			return corev1.Container{}, nil, fmt.Errorf("Step %d did not specify command", i)
+			return []corev1.Container{}, nil, fmt.Errorf("Step %d did not specify command", i)
 		}
 		if len(cmd) > 1 {
 			args = append(cmd[1:], args...)
@@ -137,7 +161,22 @@ func orderContainers(entrypointImage string, steps []corev1.Container) (corev1.C
 	// Mount the Downward volume into the first step container.
 	steps[0].VolumeMounts = append(steps[0].VolumeMounts, downwardMount)
 
-	return toolsInit, steps, nil
+	return initContainers, steps, nil
+}
+
+func resultArgument(steps []corev1.Container, results []v1alpha1.TaskResult) []string {
+	if results == nil || len(results) == 0 {
+		return nil
+	}
+	return []string{"-results", collectResultsName(results)}
+}
+
+func collectResultsName(results []v1alpha1.TaskResult) string {
+	var resultNames []string
+	for _, r := range results {
+		resultNames = append(resultNames, r.Name)
+	}
+	return strings.Join(resultNames, ",")
 }
 
 // UpdateReady updates the Pod's annotations to signal the first step to start