template: error on missing key (#15141)

* Support error_on_missing_value for templates
* Update docs for template stanza

jobspec2/parse_job.go

@@ -111,6 +111,9 @@ func normalizeTemplates(templates []*api.Template) {
 		if t.Splay == nil {
 			t.Splay = pointer.Of(5 * time.Second)
 		}
+		if t.ErrMissingKey == nil {
+			t.ErrMissingKey = pointer.Of(false)
+		}
 		normalizeChangeScript(t.ChangeScript)
 	}
 }

jobspec2/parse_test.go

@@ -1052,3 +1052,19 @@ func TestWaitConfig(t *testing.T) {
 	require.Equal(t, 5*time.Second, *tmpl.Wait.Min)
 	require.Equal(t, 60*time.Second, *tmpl.Wait.Max)
 }
+
+func TestErrMissingKey(t *testing.T) {
+	ci.Parallel(t)
+	hclBytes, err := os.ReadFile("test-fixtures/template-err-missing-key.hcl")
+	require.NoError(t, err)
+	job, err := ParseWithConfig(&ParseConfig{
+		Path:    "test-fixtures/template-err-missing-key.hcl",
+		Body:    hclBytes,
+		AllowFS: false,
+	})
+	require.NoError(t, err)
+	tmpl := job.TaskGroups[0].Tasks[0].Templates[0]
+	require.NotNil(t, tmpl)
+	require.NotNil(t, tmpl.ErrMissingKey)
+	require.True(t, *tmpl.ErrMissingKey)
+}

jobspec2/test-fixtures/template-err-missing-key.hcl

@@ -0,0 +1,9 @@
+job "example" {
+  group "group" {
+    task "task" {
+      template {
+        error_on_missing_key = true
+      }
+    }
+  }
+}