Initialize working dirs inside workspace dir

In order to allow steps to define workingDirs that are subdirectories of the workspace directory we need to make sure they have been created first since they will not exist on startup.

Fixes #725

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

@@ -26,6 +26,7 @@ import (
 	"io"
 	"io/ioutil"
 	"path/filepath"
+	"strings"
 
 	"go.uber.org/zap"
 	corev1 "k8s.io/api/core/v1"
@@ -91,9 +92,14 @@ const (
 	unnamedInitContainerPrefix = "build-step-unnamed-"
 	// Name of the credential initialization container.
 	credsInit = "credential-initializer"
+	// Name of the working dir initialization container.
+	workingDirInit = "working-dir-initializer"
 )
 
 var (
+	// The container used to initialize working directories before the build runs.
+	bashWorkingDirImage = flag.String("bash-working-dir-image", "override-with-bash-working-dir:latest",
+		"The container image for preparing our Build's working directories.")
 	// The container used to initialize credentials before the build runs.
 	credsImage = flag.String("creds-image", "override-with-creds:latest",
 		"The container image for preparing our Build's credentials.")
@@ -160,6 +166,47 @@ func makeCredentialInitializer(serviceAccountName, namespace string, kubeclient
 	}, volumes, nil
 }
 
+func makeWorkingDirScript(workingDirs []string) string {
+	seen := map[string]bool{}
+	script := ""
+	for _, wd := range workingDirs {
+		if wd != "" {
+			p := filepath.Clean(wd)
+			if rel, err := filepath.Rel(workspaceDir, p); err == nil && !strings.HasPrefix(rel, ".") && !seen[p] {
+				seen[p] = true
+				if script == "" {
+					script = fmt.Sprintf("mkdir -p %s", p)
+				} else {
+					script = fmt.Sprintf("%s %s", script, p)
+				}
+			}
+		}
+	}
+
+	return script
+}
+
+func makeWorkingDirInitializer(steps []corev1.Container) *corev1.Container {
+	workingDirs := make([]string, len(steps))
+	for _, step := range steps {
+		workingDirs = append(workingDirs, step.WorkingDir)
+	}
+
+	if script := makeWorkingDirScript(workingDirs); script != "" {
+		return &corev1.Container{
+			Name:         names.SimpleNameGenerator.RestrictLengthWithRandomSuffix(containerPrefix + workingDirInit),
+			Image:        *bashWorkingDirImage,
+			Command:      []string{"/ko-app/bash"},
+			Args:         []string{"-args", script},
+			VolumeMounts: implicitVolumeMounts,
+			Env:          implicitEnvVars,
+			WorkingDir:   workspaceDir,
+		}
+	}
+
+	return nil
+}
+
 // MakePod converts TaskRun and TaskSpec objects to a Pod which implements the taskrun specified
 // by the supplied CRD.
 func MakePod(taskRun *v1alpha1.TaskRun, taskSpec v1alpha1.TaskSpec, kubeclient kubernetes.Interface, cache *entrypoint.Cache, logger *zap.SugaredLogger) (*corev1.Pod, error) {
@@ -178,6 +225,10 @@ func MakePod(taskRun *v1alpha1.TaskRun, taskSpec v1alpha1.TaskSpec, kubeclient k
 	initContainers := []corev1.Container{*cred}
 	podContainers := []corev1.Container{}
 
+	if workingDir := makeWorkingDirInitializer(taskSpec.Steps); workingDir != nil {
+		initContainers = append(initContainers, *workingDir)
+	}
+
 	maxIndicesByResource := findMaxResourceRequest(taskSpec.Steps, corev1.ResourceCPU, corev1.ResourceMemory, corev1.ResourceEphemeralStorage)
 
 	for i := range taskSpec.Steps {

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

@@ -18,6 +18,8 @@ package resources
 
 import (
 	"crypto/rand"
+	"fmt"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -249,6 +251,52 @@ func TestMakePod(t *testing.T) {
 			},
 			Volumes: implicitVolumes,
 		},
+	}, {
+		desc: "working-dir-in-workspace-dir",
+		ts: v1alpha1.TaskSpec{
+			Steps: []corev1.Container{{
+				Name:       "name",
+				Image:      "image",
+				WorkingDir: filepath.Join(workspaceDir, "test"),
+			}},
+		},
+		want: &corev1.PodSpec{
+			RestartPolicy: corev1.RestartPolicyNever,
+			InitContainers: []corev1.Container{{
+				Name:         containerPrefix + credsInit + "-9l9zj",
+				Image:        *credsImage,
+				Command:      []string{"/ko-app/creds-init"},
+				Args:         []string{},
+				Env:          implicitEnvVars,
+				VolumeMounts: implicitVolumeMounts,
+				WorkingDir:   workspaceDir,
+			}, {
+				Name:         containerPrefix + workingDirInit + "-mz4c7",
+				Image:        *bashWorkingDirImage,
+				Command:      []string{"/ko-app/bash"},
+				Args:         []string{"-args", fmt.Sprintf("mkdir -p %s", filepath.Join(workspaceDir, "test"))},
+				Env:          implicitEnvVars,
+				VolumeMounts: implicitVolumeMounts,
+				WorkingDir:   workspaceDir,
+			}},
+			Containers: []corev1.Container{{
+				Name:         "build-step-name",
+				Image:        "image",
+				Env:          implicitEnvVars,
+				VolumeMounts: implicitVolumeMounts,
+				WorkingDir:   filepath.Join(workspaceDir, "test"),
+				Resources: corev1.ResourceRequirements{
+					Requests: corev1.ResourceList{
+						corev1.ResourceCPU:              resource.MustParse("0"),
+						corev1.ResourceMemory:           resource.MustParse("0"),
+						corev1.ResourceEphemeralStorage: resource.MustParse("0"),
+					},
+				},
+			},
+				nopContainer,
+			},
+			Volumes: implicitVolumes,
+		},
 	}} {
 		t.Run(c.desc, func(t *testing.T) {
 			names.TestingSeed()
@@ -309,3 +357,29 @@ func TestMakePod(t *testing.T) {
 		})
 	}
 }
+
+func TestMakeWorkingDirScript(t *testing.T) {
+	for _, c := range []struct {
+		desc        string
+		workingDirs []string
+		want        string
+	}{{
+		desc:        "default",
+		workingDirs: []string{"/workspace"},
+		want:        "",
+	}, {
+		desc:        "simple",
+		workingDirs: []string{"/workspace/foo", "/workspace/bar", "/baz"},
+		want:        "mkdir -p /workspace/foo /workspace/bar",
+	}, {
+		desc:        "empty",
+		workingDirs: []string{"/workspace", "", "/baz", "/workspacedir"},
+		want:        "",
+	}} {
+		t.Run(c.desc, func(t *testing.T) {
+			if script := makeWorkingDirScript(c.workingDirs); script != c.want {
+				t.Errorf("Expected `%v`, got `%v`", c.want, script)
+			}
+		})
+	}
+}