separate Step from Sidecar

Originally the Sidecar type is an alias of the Step type.
Both #3013 and #1690 will require the two types to divert from each other.
This commit separates the two types and updates code to accomodate convertListOfSteps() which originally depended on theses types to be the same.
Partially based on: https://github.com/tektoncd/pipeline/pull/3013/files

.gitignore

@@ -33,6 +33,9 @@
 # Emacs garbage
 *~
 
+# Vim garbage
+*.swp
+
 # VSCode config
 .vscode
 
@@ -49,4 +52,4 @@ cmd/*/kodata/source.tar.gz
 # binaries
 test/pullrequest/pullrequest-init
 /.bin/
-/bin/
+/bin/

pkg/apis/pipeline/v1beta1/task_types.go

@@ -125,8 +125,16 @@ type Step struct {
 	Script string `json:"script,omitempty"`
 }
 
-// A sidecar has the same data structure as a Step, consisting of a Container, and optional Script.
-type Sidecar = Step
+// Sidecar embeds the Container type, which allows it to include fields not
+// provided by Container.
+type Sidecar struct {
+	corev1.Container `json:",inline"`
+
+	// Script is the contents of an executable file to execute.
+	//
+	// If Script is not empty, the Step cannot have an Command or Args.
+	Script string `json:"script,omitempty"`
+}
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
 // TaskList contains a list of Task

pkg/pod/script.go

@@ -62,7 +62,17 @@ func convertScripts(shellImage string, steps []v1beta1.Step, sidecars []v1beta1.
 	}
 
 	convertedStepContainers := convertListOfSteps(steps, &placeScriptsInit, &placeScripts, "script")
-	sidecarContainers := convertListOfSteps(sidecars, &placeScriptsInit, &placeScripts, "sidecar-script")
+	// convertListOfSteps operates on overlapping fields across Step and Sidecar, hence a conversion
+	// from Sidecar into Step
+	sideCarSteps := []v1beta1.Step{}
+	for _, step := range sidecars {
+		sidecarStep := v1beta1.Step{
+			step.Container,
+			step.Script,
+		}
+		sideCarSteps = append(sideCarSteps, sidecarStep)
+	}
+	sidecarContainers := convertListOfSteps(sideCarSteps, &placeScriptsInit, &placeScripts, "sidecar-script")
 
 	if placeScripts {
 		return &placeScriptsInit, convertedStepContainers, sidecarContainers

pkg/pod/script_test.go

@@ -35,7 +35,7 @@ func TestConvertScripts_NothingToConvert_EmptySidecars(t *testing.T) {
 		Container: corev1.Container{
 			Image: "step-2",
 		},
-	}}, []v1alpha1.Step{})
+	}}, []v1alpha1.Sidecar{})
 	want := []corev1.Container{{
 		Image: "step-1",
 	}, {
@@ -89,7 +89,7 @@ func TestConvertScripts_NothingToConvert_WithSidecar(t *testing.T) {
 		Container: corev1.Container{
 			Image: "step-2",
 		},
-	}}, []v1alpha1.Step{{
+	}}, []v1alpha1.Sidecar{{
 		Container: corev1.Container{
 			Image: "sidecar-1",
 		},
@@ -153,7 +153,7 @@ script-3`,
 			VolumeMounts: preExistingVolumeMounts,
 			Args:         []string{"my", "args"},
 		},
-	}}, []v1alpha1.Step{})
+	}}, []v1alpha1.Sidecar{})
 	wantInit := &corev1.Container{
 		Name:    "place-scripts",
 		Image:   images.ShellImage,
@@ -241,7 +241,7 @@ script-3`,
 			VolumeMounts: preExistingVolumeMounts,
 			Args:         []string{"my", "args"},
 		},
-	}}, []v1alpha1.Step{{
+	}}, []v1alpha1.Sidecar{{
 		Script: `#!/bin/sh
 sidecar-1`,
 		Container: corev1.Container{Image: "sidecar-1"},