Add handling of working directory

config/config-feature-flags.yaml

@@ -28,3 +28,13 @@ data:
   # See https://github.com/tektoncd/pipeline/issues/2013 for more
   # info.
   disable-home-env-overwrite: "false"
+  # Setting this flag to "true" will prevent Tekton overriding your
+  # Task container's working directory.
+  #
+  # The default behaviour currently is for Tekton to override the
+  # working directory if not set by the user but this will change
+  # in an upcoming release.
+  #
+  # See https://github.com/tektoncd/pipeline/issues/1836 for more
+  # info.
+  disable-working-directory-overwrite: "false"

docs/install.md

@@ -244,6 +244,25 @@ data:
   disable-home-env-overwrite: "true" # Tekton will not overwrite $HOME in Steps.
 ```
 
+- `disable-working-directory-overwrite` - Setting this flag to "true" will prevent Tekton
+from overwriting Step containers' working directory. The default
+value is "false" and so the default behaviour is for the working directory to be 
+overwritten by Tekton with `/workspace` if the working directory is not specified explicitly
+for the step container. This default is very likely to change in an upcoming
+release. For further reference see https://github.com/tektoncd/pipeline/issues/1836.
+
+Here is an example of the `feature-flags` ConfigMap with `disable-working-directory-overwrite`
+flipped on:
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: feature-flags
+data:
+  disable-working-directory-overwrite: "true" # Tekton will not overwrite the working directory in Steps.
+```
+
 ## Custom Releases
 
 The [release Task](./../tekton/README.md) can be used for creating a custom

pkg/pod/pod.go

@@ -34,8 +34,9 @@ import (
 const (
 	homeDir = "/tekton/home"
 
-	featureFlagConfigMapName     = "feature-flags"
-	featureFlagDisableHomeEnvKey = "disable-home-env-overwrite"
+	featureFlagConfigMapName        = "feature-flags"
+	featureFlagDisableHomeEnvKey    = "disable-home-env-overwrite"
+	featureFlagDisableWorkingDirKey = "disable-working-directory-overwrite"
 
 	taskRunLabelKey = pipeline.GroupName + pipeline.TaskRunLabelKey
 )
@@ -166,8 +167,9 @@ func MakePod(images pipeline.Images, taskRun *v1alpha1.TaskRun, taskSpec v1alpha
 	// - sets container name to add "step-" prefix or "step-unnamed-#" if not specified.
 	// TODO(#1605): Remove this loop and make each transformation in
 	// isolation.
+	shouldOverrideWorkingDir := shouldOverrideWorkingDir(kubeclient)
 	for i, s := range stepContainers {
-		if s.WorkingDir == "" {
+		if s.WorkingDir == "" && shouldOverrideWorkingDir {
 			stepContainers[i].WorkingDir = pipeline.WorkspaceDir
 		}
 		if s.Name == "" {
@@ -311,3 +313,17 @@ func shouldOverrideHomeEnv(kubeclient kubernetes.Interface) bool {
 	}
 	return true
 }
+
+// shouldOverrideWorkingDir returns a bool indicating whether a Pod should have its
+// working directory overwritten with /workspace or if it should be
+// left unmodified. The default behaviour is to overwrite the working directory with '/workspace'
+// if not specified by the user,  but this is planned to change in an upcoming release.
+//
+// For further reference see https://github.com/tektoncd/pipeline/issues/1836
+func shouldOverrideWorkingDir(kubeclient kubernetes.Interface) bool {
+	configMap, err := kubeclient.CoreV1().ConfigMaps(system.GetNamespace()).Get(featureFlagConfigMapName, metav1.GetOptions{})
+	if err == nil && configMap != nil && configMap.Data != nil && configMap.Data[featureFlagDisableWorkingDirKey] == "true" {
+		return false
+	}
+	return true
+}

pkg/pod/pod_test.go

@@ -842,3 +842,45 @@ func TestShouldOverrideHomeEnv(t *testing.T) {
 		})
 	}
 }
+
+func TestShouldOverrideWorkingDir(t *testing.T) {
+	for _, tc := range []struct {
+		description string
+		configMap   *corev1.ConfigMap
+		expected    bool
+	}{{
+		description: "Default behaviour: A missing disable-working-directory-overwrite flag should result in true",
+		configMap: &corev1.ConfigMap{
+			ObjectMeta: metav1.ObjectMeta{Name: featureFlagConfigMapName, Namespace: system.GetNamespace()},
+			Data:       map[string]string{},
+		},
+		expected: true,
+	}, {
+		description: "Setting disable-working-directory-overwrite to false should result in true",
+		configMap: &corev1.ConfigMap{
+			ObjectMeta: metav1.ObjectMeta{Name: featureFlagConfigMapName, Namespace: system.GetNamespace()},
+			Data: map[string]string{
+				featureFlagDisableWorkingDirKey: "false",
+			},
+		},
+		expected: true,
+	}, {
+		description: "Setting disable-working-directory-overwrite to true should result in false",
+		configMap: &corev1.ConfigMap{
+			ObjectMeta: metav1.ObjectMeta{Name: featureFlagConfigMapName, Namespace: system.GetNamespace()},
+			Data: map[string]string{
+				featureFlagDisableWorkingDirKey: "true",
+			},
+		},
+		expected: false,
+	}} {
+		t.Run(tc.description, func(t *testing.T) {
+			kubeclient := fakek8s.NewSimpleClientset(
+				tc.configMap,
+			)
+			if result := shouldOverrideWorkingDir(kubeclient); result != tc.expected {
+				t.Errorf("Expected %t Received %t", tc.expected, result)
+			}
+		})
+	}
+}