Merge pull request #39486 from ncdc/allow-missing-keys-in-templates

hack/make-rules/test-cmd-util.sh

@@ -1045,6 +1045,33 @@ run_kubectl_get_tests() {
   kube::test::if_has_string "${output_message}" "/apis/batch/v1/namespaces/default/jobs 200 OK"
   kube::test::if_has_string "${output_message}" "/apis/extensions/v1beta1/namespaces/default/deployments 200 OK"
   kube::test::if_has_string "${output_message}" "/apis/extensions/v1beta1/namespaces/default/replicasets 200 OK"
+
+  ### Test --allow-missing-template-keys
+  # Pre-condition: no POD exists
+  create_and_use_new_namespace
+  kube::test::get_object_assert pods "{{range.items}}{{$id_field}}:{{end}}" ''
+  # Command
+  kubectl create -f test/fixtures/doc-yaml/admin/limitrange/valid-pod.yaml "${kube_flags[@]}"
+  # Post-condition: valid-pod POD is created
+  kubectl get "${kube_flags[@]}" pods -o json
+  kube::test::get_object_assert pods "{{range.items}}{{$id_field}}:{{end}}" 'valid-pod:'
+
+  ## check --allow-missing-template-keys defaults to true for jsonpath templates
+  kubectl get "${kube_flags[@]}" pod valid-pod -o jsonpath='{.missing}'
+
+  ## check --allow-missing-template-keys defaults to true for go templates
+  kubectl get "${kube_flags[@]}" pod valid-pod -o go-template='{{.missing}}'
+
+  ## check --allow-missing-template-keys=false results in an error for a missing key with jsonpath
+  output_message=$(! kubectl get pod valid-pod --allow-missing-template-keys=false -o jsonpath='{.missing}' "${kube_flags[@]}")
+  kube::test::if_has_string "${output_message}" 'error executing jsonpath "{.missing}": missing is not found'
+
+  ## check --allow-missing-template-keys=false results in an error for a missing key with go
+  output_message=$(! kubectl get pod valid-pod --allow-missing-template-keys=false -o go-template='{{.missing}}' "${kube_flags[@]}")
+  kube::test::if_has_string "${output_message}" 'error executing template "{{.missing}}": template: output:1:2: executing "output" at <.missing>: map has no entry for key "missing"'
+
+  # cleanup
+  kubectl delete pods valid-pod "${kube_flags[@]}"
 }
 
 run_kubectl_request_timeout_tests() {

hack/verify-flags/known-flags.txt

@@ -7,6 +7,7 @@ advertised-address
 algorithm-provider
 all-namespaces
 allocate-node-cidrs
+allow-missing-template-keys
 allow-privileged
 allowed-not-ready-nodes
 anonymous-auth

pkg/kubectl/cmd/clusterinfo_dump.go

@@ -91,7 +91,7 @@ func dumpClusterInfo(f cmdutil.Factory, cmd *cobra.Command, args []string, out i
 		return err
 	}
 
-	printer, _, err := kubectl.GetPrinter("json", "", false)
+	printer, _, err := kubectl.GetPrinter("json", "", false, true)
 	if err != nil {
 		return err
 	}

pkg/kubectl/cmd/convert.go

@@ -146,7 +146,7 @@ func (o *ConvertOptions) Complete(f cmdutil.Factory, out io.Writer, cmd *cobra.C
 		}
 	}
 	o.encoder = f.JSONEncoder()
-	o.printer, _, err = kubectl.GetPrinter(outputFormat, templateFile, false)
+	o.printer, _, err = kubectl.GetPrinter(outputFormat, templateFile, false, cmdutil.GetFlagBool(cmd, "allow-missing-template-keys"))
 	if err != nil {
 		return err
 	}

pkg/kubectl/cmd/util/printing.go

@@ -49,6 +49,7 @@ func AddOutputFlagsForMutation(cmd *cobra.Command) {
 // AddOutputFlags adds output related flags to a command.
 func AddOutputFlags(cmd *cobra.Command) {
 	cmd.Flags().StringP("output", "o", "", "Output format. One of: json|yaml|wide|name|custom-columns=...|custom-columns-file=...|go-template=...|go-template-file=...|jsonpath=...|jsonpath-file=... See custom columns [http://kubernetes.io/docs/user-guide/kubectl-overview/#custom-columns], golang template [http://golang.org/pkg/text/template/#pkg-overview] and jsonpath template [http://kubernetes.io/docs/user-guide/jsonpath].")
+	cmd.Flags().Bool("allow-missing-template-keys", true, "If true, ignore any errors in templates when a field or map key is missing in the template. Only applies to golang and jsonpath output formats.")
 }
 
 // AddNoHeadersFlags adds no-headers flags to a command.
@@ -126,7 +127,13 @@ func PrinterForCommand(cmd *cobra.Command) (kubectl.ResourcePrinter, bool, error
 		}
 	}
 
-	printer, generic, err := kubectl.GetPrinter(outputFormat, templateFile, GetFlagBool(cmd, "no-headers"))
+	// this function may be invoked by a command that did not call AddPrinterFlags first, so we need
+	// to be safe about how we access the allow-missing-template-keys flag
+	allowMissingTemplateKeys := false
+	if cmd.Flags().Lookup("allow-missing-template-keys") != nil {
+		allowMissingTemplateKeys = GetFlagBool(cmd, "allow-missing-template-keys")
+	}
+	printer, generic, err := kubectl.GetPrinter(outputFormat, templateFile, GetFlagBool(cmd, "no-headers"), allowMissingTemplateKeys)
 	if err != nil {
 		return nil, generic, err
 	}

pkg/kubectl/resource_printer.go

@@ -71,7 +71,7 @@ const (
 // is agnostic to schema versions, so you must send arguments to PrintObj in the
 // version you wish them to be shown using a VersionedPrinter (typically when
 // generic is true).
-func GetPrinter(format, formatArgument string, noHeaders bool) (ResourcePrinter, bool, error) {
+func GetPrinter(format, formatArgument string, noHeaders, allowMissingTemplateKeys bool) (ResourcePrinter, bool, error) {
 	var printer ResourcePrinter
 	switch format {
 	case "json":
@@ -88,11 +88,12 @@ func GetPrinter(format, formatArgument string, noHeaders bool) (ResourcePrinter,
 		if len(formatArgument) == 0 {
 			return nil, false, fmt.Errorf("template format specified but no template given")
 		}
-		var err error
-		printer, err = NewTemplatePrinter([]byte(formatArgument))
+		templatePrinter, err := NewTemplatePrinter([]byte(formatArgument))
 		if err != nil {
 			return nil, false, fmt.Errorf("error parsing template %s, %v\n", formatArgument, err)
 		}
+		templatePrinter.AllowMissingKeys(allowMissingTemplateKeys)
+		printer = templatePrinter
 	case "templatefile", "go-template-file":
 		if len(formatArgument) == 0 {
 			return nil, false, fmt.Errorf("templatefile format specified but no template file given")
@@ -101,19 +102,22 @@ func GetPrinter(format, formatArgument string, noHeaders bool) (ResourcePrinter,
 		if err != nil {
 			return nil, false, fmt.Errorf("error reading template %s, %v\n", formatArgument, err)
 		}
-		printer, err = NewTemplatePrinter(data)
+		templatePrinter, err := NewTemplatePrinter(data)
 		if err != nil {
 			return nil, false, fmt.Errorf("error parsing template %s, %v\n", string(data), err)
 		}
+		templatePrinter.AllowMissingKeys(allowMissingTemplateKeys)
+		printer = templatePrinter
 	case "jsonpath":
 		if len(formatArgument) == 0 {
 			return nil, false, fmt.Errorf("jsonpath template format specified but no template given")
 		}
-		var err error
-		printer, err = NewJSONPathPrinter(formatArgument)
+		jsonpathPrinter, err := NewJSONPathPrinter(formatArgument)
 		if err != nil {
 			return nil, false, fmt.Errorf("error parsing jsonpath %s, %v\n", formatArgument, err)
 		}
+		jsonpathPrinter.AllowMissingKeys(allowMissingTemplateKeys)
+		printer = jsonpathPrinter
 	case "jsonpath-file":
 		if len(formatArgument) == 0 {
 			return nil, false, fmt.Errorf("jsonpath file format specified but no template file file given")
@@ -122,10 +126,12 @@ func GetPrinter(format, formatArgument string, noHeaders bool) (ResourcePrinter,
 		if err != nil {
 			return nil, false, fmt.Errorf("error reading template %s, %v\n", formatArgument, err)
 		}
-		printer, err = NewJSONPathPrinter(string(data))
+		jsonpathPrinter, err := NewJSONPathPrinter(string(data))
 		if err != nil {
 			return nil, false, fmt.Errorf("error parsing template %s, %v\n", string(data), err)
 		}
+		jsonpathPrinter.AllowMissingKeys(allowMissingTemplateKeys)
+		printer = jsonpathPrinter
 	case "custom-columns":
 		var err error
 		if printer, err = NewCustomColumnsPrinterFromSpec(formatArgument, api.Codecs.UniversalDecoder(), noHeaders); err != nil {
@@ -2512,6 +2518,15 @@ func NewTemplatePrinter(tmpl []byte) (*TemplatePrinter, error) {
 	}, nil
 }
 
+// AllowMissingKeys tells the template engine if missing keys are allowed.
+func (p *TemplatePrinter) AllowMissingKeys(allow bool) {
+	if allow {
+		p.template.Option("missingkey=default")
+	} else {
+		p.template.Option("missingkey=error")
+	}
+}
+
 func (p *TemplatePrinter) AfterPrint(w io.Writer, res string) error {
 	return nil
 }

pkg/kubectl/resource_printer_test.go

@@ -78,7 +78,7 @@ func TestVersionedPrinter(t *testing.T) {
 }
 
 func TestPrintDefault(t *testing.T) {
-	printer, found, err := GetPrinter("", "", false)
+	printer, found, err := GetPrinter("", "", false, false)
 	if err != nil {
 		t.Fatalf("unexpected error: %#v", err)
 	}
@@ -133,7 +133,7 @@ func TestPrinter(t *testing.T) {
 	}
 	for _, test := range printerTests {
 		buf := bytes.NewBuffer([]byte{})
-		printer, generic, err := GetPrinter(test.Format, test.FormatArgument, false)
+		printer, generic, err := GetPrinter(test.Format, test.FormatArgument, false, true)
 		if err != nil {
 			t.Errorf("in %s, unexpected error: %#v", test.Name, err)
 		}
@@ -163,7 +163,7 @@ func TestBadPrinter(t *testing.T) {
 		{"bad jsonpath", "jsonpath", "{.Name", fmt.Errorf("error parsing jsonpath {.Name, unclosed action\n")},
 	}
 	for _, test := range badPrinterTests {
-		_, _, err := GetPrinter(test.Format, test.FormatArgument, false)
+		_, _, err := GetPrinter(test.Format, test.FormatArgument, false, false)
 		if err == nil || err.Error() != test.Error.Error() {
 			t.Errorf("in %s, expect %s, got %s", test.Name, test.Error, err)
 		}
@@ -356,7 +356,7 @@ func TestNamePrinter(t *testing.T) {
 			},
 			"pod/foo\npod/bar\n"},
 	}
-	printer, _, _ := GetPrinter("name", "", false)
+	printer, _, _ := GetPrinter("name", "", false, false)
 	for name, item := range tests {
 		buff := &bytes.Buffer{}
 		err := printer.PrintObj(item.obj, buff)
@@ -1794,3 +1794,43 @@ func TestPrintPodDisruptionBudget(t *testing.T) {
 		buf.Reset()
 	}
 }
+
+func TestAllowMissingKeys(t *testing.T) {
+	tests := []struct {
+		Name                     string
+		AllowMissingTemplateKeys bool
+		Format                   string
+		Template                 string
+		Input                    runtime.Object
+		Expect                   string
+		Error                    string
+	}{
+		{"test template, allow missing keys", true, "template", "{{.blarg}}", &api.Pod{}, "<no value>", ""},
+		{"test template, strict", false, "template", "{{.blarg}}", &api.Pod{}, "", `error executing template "{{.blarg}}": template: output:1:2: executing "output" at <.blarg>: map has no entry for key "blarg"`},
+		{"test jsonpath, allow missing keys", true, "jsonpath", "{.blarg}", &api.Pod{}, "", ""},
+		{"test jsonpath, strict", false, "jsonpath", "{.blarg}", &api.Pod{}, "", "error executing jsonpath \"{.blarg}\": blarg is not found\n"},
+	}
+	for _, test := range tests {
+		buf := bytes.NewBuffer([]byte{})
+		printer, _, err := GetPrinter(test.Format, test.Template, false, test.AllowMissingTemplateKeys)
+		if err != nil {
+			t.Errorf("in %s, unexpected error: %#v", test.Name, err)
+		}
+		err = printer.PrintObj(test.Input, buf)
+		if len(test.Error) == 0 && err != nil {
+			t.Errorf("in %s, unexpected error: %v", test.Name, err)
+			continue
+		}
+		if len(test.Error) > 0 {
+			if err == nil {
+				t.Errorf("in %s, expected to get error: %v", test.Name, test.Error)
+			} else if e, a := test.Error, err.Error(); e != a {
+				t.Errorf("in %s, expected error %q, got %q", test.Name, e, a)
+			}
+			continue
+		}
+		if buf.String() != test.Expect {
+			t.Errorf("in %s, expect %q, got %q", test.Name, test.Expect, buf.String())
+		}
+	}
+}