chore: Improve error reporting for `helm template --debug` with `--show-only`

Signed-off-by: Jeaeun Kim <me@kyoku.dev>

pkg/cmd/template.go

@@ -177,7 +177,12 @@ func newTemplateCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 							missing = false
 						}
 						if missing {
-							return fmt.Errorf("could not find template %s in chart", f)
+							if err != nil && settings.Debug {
+								// assume the manifest itself is too malformed to be rendered
+								return err
+							} else {
+								return fmt.Errorf("could not find template %s in chart", f)
+							}
 						}
 					}
 					for _, m := range manifestsToRender {

pkg/cmd/template_test.go

@@ -133,6 +133,12 @@ func TestTemplateCmd(t *testing.T) {
 			wantError: true,
 			golden:    "output/template-with-invalid-yaml-debug.txt",
 		},
+		{
+			name:      "chart with template with invalid template expression (--debug, --show-only)",
+			cmd:       fmt.Sprintf("template '%s' --debug --show-only %s", "testdata/testcharts/chart-with-template-with-invalid-template-expr", "templates/alpine-pod.yaml"),
+			wantError: true,
+			golden:    "output/template-with-invalid-template-expr-debug-show-only.txt",
+		},
 		{
 			name:   "template skip-tests",
 			cmd:    fmt.Sprintf(`template '%s' --skip-tests`, chartPath),

pkg/cmd/testdata/output/template-with-invalid-template-expr-debug-show-only.txt

@@ -0,0 +1,3 @@
+Error: chart-with-template-with-invalid-template-expr/templates/alpine-pod.yaml:7:38
+  executing "chart-with-template-with-invalid-template-expr/templates/alpine-pod.yaml" at <b64enc>:
+    invalid value; expected string

pkg/cmd/testdata/testcharts/chart-with-template-with-invalid-template-expr/Chart.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+description: Deploy a basic Alpine Linux pod
+home: https://helm.sh/helm
+name: chart-with-template-with-invalid-template-expr
+sources:
+  - https://github.com/helm/helm
+version: 0.1.0
+type: application

pkg/cmd/testdata/testcharts/chart-with-template-with-invalid-template-expr/README.md

@@ -0,0 +1,13 @@
+#Alpine: A simple Helm chart
+
+Run a single pod of Alpine Linux.
+
+This example was generated using the command `helm create alpine`.
+
+The `templates/` directory contains a very simple pod resource with a
+couple of parameters.
+
+The `values.yaml` file contains the default values for the
+`alpine-pod.yaml` template.
+
+You can install this example using `helm install ./alpine`.

pkg/cmd/testdata/testcharts/chart-with-template-with-invalid-template-expr/templates/alpine-pod.yaml

@@ -0,0 +1,9 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: "{{.Release.Name}}-{{.Values.Name}}"
+spec:
+  containers:
+  - name: {{ .Values.nonExistentKey | b64enc }}
+    image: "alpine:3.9"
+    command: ["/bin/sleep","9000"]

pkg/cmd/testdata/testcharts/chart-with-template-with-invalid-template-expr/values.yaml

@@ -0,0 +1 @@
+Name: my-alpine