Reserve /tekton/ paths and "tekton-internal-" volume names

This prevents collisions between user-specified volumes and
Tekton-internal volumes used to support execution.

Some validation changes:
- volume names starting with "tekton-internal-" are not valid
- volumeMounts that mount at /tekton/* are not valid

Tekton's own internal volume mounts are already mounted at /tekton/*,
and now all volume names start with "tekton-internal-"

Some Tekton-internal volume names were previously randomized to prevent
collisions, which is no longer necessary, so they're no longer
randomized.

creds-init mounts annotated K8s secrets into the creds-init process.
Previously those were mounted at /var/build-secrets/* (a relic of
knative/build times). Now those are mounted at /tekton/creds-secrets/*

Some init container names were also randomly generated, which is
unnecessary, so that's gone too.

cmd/entrypoint/README.md

@@ -20,15 +20,15 @@ The following flags are available :
   content.
 
 The following example of usage for `entrypoint`, wait's for
-`/builder/downward/ready` file to exists and have some content before
+`/tekton/downward/ready` file to exists and have some content before
 executing `/ko-app/bash -- -args mkdir -p /workspace/git-resource`,
-and will write to `/builder/tools/0` in casse of succes, or
-`/builder/tools/0.err` in case of failure.
+and will write to `/tekton/tools/0` in casse of succes, or
+`/tekton/tools/0.err` in case of failure.
 
 ```
 entrypoint \
-	-wait_file /builder/downward/ready \
-	-post_file /builder/tools/0" \
+	-wait_file /tekton/downward/ready \
+	-post_file /tekton/tools/0" \
 	-wait_file_content  \
 	-entrypoint /ko-app/bash -- -args mkdir -p /workspace/git-resource
 ```

docs/developers/README.md

@@ -144,12 +144,11 @@ If the image is a private registry, the service account should include an
 
 ## Builder namespace on containers
 
-The `/builder/` namespace is reserved on containers for various system tools,
+The `/tekton/` namespace is reserved on containers for various system tools,
 such as the following:
 
 - The environment variable HOME is set to `/tekton/home`, used by the builder
   tools and injected on into all of the step containers
-- Default location for output-images `/builder/output-images`
 
 ## Handling of injected sidecars
 

pkg/apis/pipeline/v1alpha1/task_validation.go

@@ -126,27 +126,41 @@ func ValidateVolumes(volumes []corev1.Volume) *apis.FieldError {
 func validateSteps(steps []Step) *apis.FieldError {
 	// Task must not have duplicate step names.
 	names := map[string]struct{}{}
-	for _, s := range steps {
+	for idx, s := range steps {
 		if s.Image == "" {
 			return apis.ErrMissingField("Image")
 		}
 
 		if s.Script != "" {
 			if len(s.Command) > 0 {
 				return &apis.FieldError{
-					Message: "script cannot be used with command",
+					Message: fmt.Sprintf("step %d script cannot be used with command", idx),
 					Paths:   []string{"script"},
 				}
 			}
 		}
 
-		if s.Name == "" {
-			continue
+		if s.Name != "" {
+			if _, ok := names[s.Name]; ok {
+				return apis.ErrInvalidValue(s.Name, "name")
+			}
+			names[s.Name] = struct{}{}
 		}
-		if _, ok := names[s.Name]; ok {
-			return apis.ErrInvalidValue(s.Name, "name")
+
+		for _, vm := range s.VolumeMounts {
+			if strings.HasPrefix(vm.MountPath, "/tekton/") {
+				return &apis.FieldError{
+					Message: fmt.Sprintf("step %d volumeMount cannot be mounted under /tekton/ (volumeMount %q mounted at %q)", idx, vm.Name, vm.MountPath),
+					Paths:   []string{"volumeMounts.mountPath"},
+				}
+			}
+			if strings.HasPrefix(vm.Name, "tekton-internal-") {
+				return &apis.FieldError{
+					Message: fmt.Sprintf(`step %d volumeMount name %q cannot start with "tekton-internal-"`, idx, vm.Name),
+					Paths:   []string{"volumeMounts.name"},
+				}
+			}
 		}
-		names[s.Name] = struct{}{}
 	}
 	return nil
 }

pkg/apis/pipeline/v1alpha1/task_validation_test.go

@@ -643,9 +643,39 @@ func TestTaskSpecValidateError(t *testing.T) {
 			}},
 		},
 		expectedError: apis.FieldError{
-			Message: "script cannot be used with command",
+			Message: "step 0 script cannot be used with command",
 			Paths:   []string{"steps.script"},
 		},
+	}, {
+		name: "step volume mounts under /tekton/",
+		fields: fields{
+			Steps: []v1alpha1.Step{{Container: corev1.Container{
+				Image: "myimage",
+				VolumeMounts: []corev1.VolumeMount{{
+					Name:      "foo",
+					MountPath: "/tekton/foo",
+				}},
+			}}},
+		},
+		expectedError: apis.FieldError{
+			Message: `step 0 volumeMount cannot be mounted under /tekton/ (volumeMount "foo" mounted at "/tekton/foo")`,
+			Paths:   []string{"steps.volumeMounts.mountPath"},
+		},
+	}, {
+		name: "step volume mount name starts with tekton-internal-",
+		fields: fields{
+			Steps: []v1alpha1.Step{{Container: corev1.Container{
+				Image: "myimage",
+				VolumeMounts: []corev1.VolumeMount{{
+					Name:      "tekton-internal-foo",
+					MountPath: "/this/is/fine",
+				}},
+			}}},
+		},
+		expectedError: apis.FieldError{
+			Message: `step 0 volumeMount name "tekton-internal-foo" cannot start with "tekton-internal-"`,
+			Paths:   []string{"steps.volumeMounts.name"},
+		},
 	}}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

pkg/credentials/initialize.go

@@ -26,7 +26,7 @@ import (
 
 // VolumePath is the path where build secrets are written.
 // It is mutable and exported for testing.
-var VolumePath = "/var/build-secrets"
+var VolumePath = "/tekton/creds-secrets"
 
 // Builder is the interface for a credential initializer of any type.
 type Builder interface {

pkg/pod/creds_init.go

@@ -22,7 +22,6 @@ import (
 	"github.com/tektoncd/pipeline/pkg/credentials"
 	"github.com/tektoncd/pipeline/pkg/credentials/dockercreds"
 	"github.com/tektoncd/pipeline/pkg/credentials/gitcreds"
-	"github.com/tektoncd/pipeline/pkg/names"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
@@ -65,7 +64,7 @@ func credsInit(credsImage string, serviceAccountName, namespace string, kubeclie
 		}
 
 		if matched {
-			name := names.SimpleNameGenerator.RestrictLengthWithRandomSuffix(fmt.Sprintf("secret-volume-%s", secret.Name))
+			name := fmt.Sprintf("tekton-internal-secret-volume-%s", secret.Name)
 			volumeMounts = append(volumeMounts, corev1.VolumeMount{
 				Name:      name,
 				MountPath: credentials.VolumeName(secret.Name),
@@ -87,7 +86,7 @@ func credsInit(credsImage string, serviceAccountName, namespace string, kubeclie
 	}
 
 	return &corev1.Container{
-		Name:         names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("credential-initializer"),
+		Name:         "credential-initializer",
 		Image:        credsImage,
 		Command:      []string{"/ko-app/creds-init"},
 		Args:         args,

pkg/pod/creds_init_test.go

@@ -99,7 +99,7 @@ func TestCredsInit(t *testing.T) {
 			},
 		},
 		want: &corev1.Container{
-			Name:    "credential-initializer-mz4c7",
+			Name:    "credential-initializer",
 			Image:   images.CredsImage,
 			Command: []string{"/ko-app/creds-init"},
 			Args: []string{
@@ -110,8 +110,8 @@ func TestCredsInit(t *testing.T) {
 			},
 			Env: envVars,
 			VolumeMounts: append(volumeMounts, corev1.VolumeMount{
-				Name:      "secret-volume-my-creds-9l9zj",
-				MountPath: "/var/build-secrets/my-creds",
+				Name:      "tekton-internal-secret-volume-my-creds",
+				MountPath: "/tekton/creds-secrets/my-creds",
 			}),
 		},
 	}} {

pkg/pod/entrypoint.go

@@ -28,11 +28,11 @@ import (
 )
 
 const (
-	toolsVolumeName  = "tools"
+	toolsVolumeName  = "tekton-internal-tools"
 	mountPoint       = "/tekton/tools"
 	entrypointBinary = mountPoint + "/entrypoint"
 
-	downwardVolumeName     = "downward"
+	downwardVolumeName     = "tekton-internal-downward"
 	downwardMountPoint     = "/tekton/downward"
 	downwardMountReadyFile = "ready"
 	readyAnnotation        = "tekton.dev/ready"

pkg/pod/pod.go

@@ -30,8 +30,10 @@ import (
 )
 
 const (
-	workspaceDir = "/workspace"
-	homeDir      = "/tekton/home"
+	workspaceVolumeName = "tekton-internal-workspace"
+	homeVolumeName      = "tekton-internal-home"
+	workspaceDir        = "/workspace"
+	homeDir             = "/tekton/home"
 
 	taskRunLabelKey     = pipeline.GroupName + pipeline.TaskRunLabelKey
 	ManagedByLabelKey   = "app.kubernetes.io/managed-by"
@@ -51,17 +53,17 @@ var (
 		Value: homeDir,
 	}}
 	implicitVolumeMounts = []corev1.VolumeMount{{
-		Name:      "workspace",
+		Name:      "tekton-internal-workspace",
 		MountPath: workspaceDir,
 	}, {
-		Name:      "tekton-home",
+		Name:      "tekton-internal-home",
 		MountPath: homeDir,
 	}}
 	implicitVolumes = []corev1.Volume{{
-		Name:         "workspace",
+		Name:         "tekton-internal-workspace",
 		VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}},
 	}, {
-		Name:         "tekton-home",
+		Name:         "tekton-internal-home",
 		VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}},
 	}}
 )
@@ -99,7 +101,7 @@ func MakePod(images pipeline.Images, taskRun *v1alpha1.TaskRun, taskSpec v1alpha
 	}
 
 	// Initialize any workingDirs under /workspace.
-	if workingDirInit := workingDirInit(images.ShellImage, stepContainers, implicitVolumeMounts); workingDirInit != nil {
+	if workingDirInit := workingDirInit(images.ShellImage, stepContainers); workingDirInit != nil {
 		initContainers = append(initContainers, *workingDirInit)
 	}
 

pkg/pod/pod_test.go

@@ -44,11 +44,11 @@ func TestMakePod(t *testing.T) {
 	names.TestingSeed()
 
 	secretsVolumeMount := corev1.VolumeMount{
-		Name:      "secret-volume-multi-creds-9l9zj",
-		MountPath: "/var/build-secrets/multi-creds",
+		Name:      "tekton-internal-secret-volume-multi-creds",
+		MountPath: "/tekton/creds-secrets/multi-creds",
 	}
 	secretsVolume := corev1.Volume{
-		Name:         "secret-volume-multi-creds-9l9zj",
+		Name:         "tekton-internal-secret-volume-multi-creds",
 		VolumeSource: corev1.VolumeSource{Secret: &corev1.SecretVolumeSource{SecretName: "multi-creds"}},
 	}
 
@@ -116,7 +116,7 @@ func TestMakePod(t *testing.T) {
 			ServiceAccountName: "service-account",
 			RestartPolicy:      corev1.RestartPolicyNever,
 			InitContainers: []corev1.Container{{
-				Name:    "credential-initializer-mz4c7",
+				Name:    "credential-initializer",
 				Image:   images.CredsImage,
 				Command: []string{"/ko-app/creds-init"},
 				Args: []string{
@@ -279,7 +279,7 @@ func TestMakePod(t *testing.T) {
 		want: &corev1.PodSpec{
 			RestartPolicy: corev1.RestartPolicyNever,
 			InitContainers: []corev1.Container{{
-				Name:         "working-dir-initializer-mz4c7",
+				Name:         "working-dir-initializer",
 				Image:        images.ShellImage,
 				Command:      []string{"sh"},
 				Args:         []string{"-c", fmt.Sprintf("mkdir -p %s", filepath.Join(workspaceDir, "test"))},
@@ -455,22 +455,22 @@ print("Hello from Python")`,
 		want: &corev1.PodSpec{
 			RestartPolicy: corev1.RestartPolicyNever,
 			InitContainers: []corev1.Container{{
-				Name:    "place-scripts-9l9zj",
+				Name:    "place-scripts",
 				Image:   images.ShellImage,
 				Command: []string{"sh"},
 				TTY:     true,
-				Args: []string{"-c", `tmpfile="/tekton/scripts/script-0-mz4c7"
+				Args: []string{"-c", `tmpfile="/tekton/scripts/script-0-9l9zj"
 touch ${tmpfile} && chmod +x ${tmpfile}
-cat > ${tmpfile} << 'script-heredoc-randomly-generated-mssqb'
+cat > ${tmpfile} << 'script-heredoc-randomly-generated-mz4c7'
 #!/bin/sh
 echo hello from step one
-script-heredoc-randomly-generated-mssqb
-tmpfile="/tekton/scripts/script-1-78c5n"
+script-heredoc-randomly-generated-mz4c7
+tmpfile="/tekton/scripts/script-1-mssqb"
 touch ${tmpfile} && chmod +x ${tmpfile}
-cat > ${tmpfile} << 'script-heredoc-randomly-generated-6nl7g'
+cat > ${tmpfile} << 'script-heredoc-randomly-generated-78c5n'
 #!/usr/bin/env python
 print("Hello from Python")
-script-heredoc-randomly-generated-6nl7g
+script-heredoc-randomly-generated-78c5n
 `},
 				VolumeMounts: []corev1.VolumeMount{scriptsVolumeMount},
 			}, {
@@ -490,7 +490,7 @@ script-heredoc-randomly-generated-6nl7g
 					"-post_file",
 					"/tekton/tools/0",
 					"-entrypoint",
-					"/tekton/scripts/script-0-mz4c7",
+					"/tekton/scripts/script-0-9l9zj",
 					"--",
 					"template",
 					"args",
@@ -509,7 +509,7 @@ script-heredoc-randomly-generated-6nl7g
 					"-post_file",
 					"/tekton/tools/1",
 					"-entrypoint",
-					"/tekton/scripts/script-1-78c5n",
+					"/tekton/scripts/script-1-mssqb",
 					"--",
 					"template",
 					"args",

pkg/pod/script.go

@@ -27,15 +27,14 @@ import (
 )
 
 const (
-	scriptsVolumeName = "scripts"
+	scriptsVolumeName = "tekton-internal-scripts"
 	scriptsDir        = "/tekton/scripts"
 	defaultShebang    = "#!/bin/sh\n"
 )
 
 var (
 	// Volume definition attached to Pods generated from TaskRuns that have
 	// steps that specify a Script.
-	// TODO(#1605): Generate volumeMount names, to avoid collisions.
 	scriptsVolume = corev1.Volume{
 		Name:         scriptsVolumeName,
 		VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}},
@@ -54,7 +53,7 @@ var (
 func convertScripts(shellImage string, steps []v1alpha1.Step) (*corev1.Container, []corev1.Container) {
 	placeScripts := false
 	placeScriptsInit := corev1.Container{
-		Name:         names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("place-scripts"),
+		Name:         "place-scripts",
 		Image:        shellImage,
 		TTY:          true,
 		Command:      []string{"sh"},