Merge pull request kubernetes#61501 from juanvallejo/jvallejo/add-custom-columns-flags

Automatic merge from submit-queue (batch tested with PRs 61434, 61501, 59609, 61467, 61531). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

wire through custom-column print flags

**Release note**:
```release-note
NONE
```
Begin implementing pieces needed to retrieve custom-column printers from a set of flags.
Proposal: https://docs.google.com/document/d/19ZZFVe9oD1KQmk5uExggRWtRl_hKGfYnBXvHZJlgEro/edit#heading=h.pnvbfi14v4zz

cc @soltysh @deads2k @pwittrock

Author: Kubernetes Submit Queue

pkg/printers/BUILD

@@ -10,6 +10,7 @@ go_library(
     name = "go_default_library",
     srcs = [
         "customcolumn.go",
+        "customcolumn_flags.go",
         "humanreadable.go",
         "interface.go",
         "json.go",
@@ -44,6 +45,7 @@ go_library(
 go_test(
     name = "go_default_xtest",
     srcs = [
+        "customcolumn_flags_test.go",
         "customcolumn_test.go",
         "json_yaml_flags_test.go",
         "name_flags_test.go",

pkg/printers/customcolumn_flags.go

@@ -0,0 +1,101 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package printers
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"k8s.io/kubernetes/pkg/kubectl/scheme"
+)
+
+// CustomColumnsPrintFlags provides default flags necessary for printing
+// custom resource columns from an inline-template or file.
+type CustomColumnsPrintFlags struct {
+	NoHeaders        bool
+	TemplateArgument string
+}
+
+// ToPrinter receives an templateFormat and returns a printer capable of
+// handling custom-column printing.
+// Returns false if the specified templateFormat does not match a supported format.
+// Supported format types can be found in pkg/printers/printers.go
+func (f *CustomColumnsPrintFlags) ToPrinter(templateFormat string) (ResourcePrinter, bool, error) {
+	if len(templateFormat) == 0 {
+		return nil, false, fmt.Errorf("missing output format")
+	}
+
+	templateValue := ""
+
+	supportedFormats := map[string]bool{
+		"custom-columns-file": true,
+		"custom-columns":      true,
+	}
+
+	if len(f.TemplateArgument) == 0 {
+		for format := range supportedFormats {
+			format = format + "="
+			if strings.HasPrefix(templateFormat, format) {
+				templateValue = templateFormat[len(format):]
+				templateFormat = format[:len(format)-1]
+				break
+			}
+		}
+	} else {
+		templateValue = f.TemplateArgument
+	}
+
+	if _, supportedFormat := supportedFormats[templateFormat]; !supportedFormat {
+		return nil, false, nil
+	}
+
+	if len(templateValue) == 0 {
+		return nil, true, fmt.Errorf("custom-columns format specified but no custom columns given")
+	}
+
+	decoder := scheme.Codecs.UniversalDecoder()
+
+	if templateFormat == "custom-columns-file" {
+		file, err := os.Open(templateValue)
+		if err != nil {
+			return nil, true, fmt.Errorf("error reading template %s, %v\n", templateValue, err)
+		}
+		defer file.Close()
+		p, err := NewCustomColumnsPrinterFromTemplate(file, decoder)
+		return p, true, err
+	}
+
+	p, err := NewCustomColumnsPrinterFromSpec(templateValue, decoder, f.NoHeaders)
+	return p, true, err
+}
+
+// AddFlags receives a *cobra.Command reference and binds
+// flags related to custom-columns printing
+func (f *CustomColumnsPrintFlags) AddFlags(c *cobra.Command) {}
+
+// NewCustomColumnsPrintFlags returns flags associated with
+// custom-column printing, with default values set.
+// NoHeaders and TemplateArgument should be set by callers.
+func NewCustomColumnsPrintFlags(noHeaders bool, templateValue string) *CustomColumnsPrintFlags {
+	return &CustomColumnsPrintFlags{
+		NoHeaders:        noHeaders,
+		TemplateArgument: templateValue,
+	}
+}

pkg/printers/customcolumn_flags_test.go

@@ -0,0 +1,139 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package printers_test
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+	"testing"
+
+	"k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/kubernetes/pkg/printers"
+)
+
+func TestPrinterSupportsExpectedCustomColumnFormats(t *testing.T) {
+	testObject := &v1.Pod{ObjectMeta: metav1.ObjectMeta{Name: "foo"}}
+
+	customColumnsFile, err := ioutil.TempFile("", "printers_jsonpath_flags")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer func(tempFile *os.File) {
+		tempFile.Close()
+		os.Remove(tempFile.Name())
+	}(customColumnsFile)
+
+	fmt.Fprintf(customColumnsFile, "NAME\n.metadata.name")
+
+	testCases := []struct {
+		name               string
+		outputFormat       string
+		templateArg        string
+		expectedError      string
+		expectedParseError string
+		expectedOutput     string
+		expectNoMatch      bool
+	}{
+		{
+			name:           "valid output format also containing the custom-columns argument succeeds",
+			outputFormat:   "custom-columns=NAME:.metadata.name",
+			expectedOutput: "foo",
+		},
+		{
+			name:          "valid output format and no --template argument results in an error",
+			outputFormat:  "custom-columns",
+			expectedError: "custom-columns format specified but no custom columns given",
+		},
+		{
+			name:           "valid output format and --template argument succeeds",
+			outputFormat:   "custom-columns",
+			templateArg:    "NAME:.metadata.name",
+			expectedOutput: "foo",
+		},
+		{
+			name:           "custom-columns template file should match, and successfully return correct value",
+			outputFormat:   "custom-columns-file",
+			templateArg:    customColumnsFile.Name(),
+			expectedOutput: "foo",
+		},
+		{
+			name:          "valid output format and invalid --template argument results in a parsing error from the printer",
+			outputFormat:  "custom-columns",
+			templateArg:   "invalid",
+			expectedError: "unexpected custom-columns spec: invalid, expected <header>:<json-path-expr>",
+		},
+		{
+			name:          "no printer is matched on an invalid outputFormat",
+			outputFormat:  "invalid",
+			expectNoMatch: true,
+		},
+		{
+			name:          "custom-columns printer should not match on any other format supported by another printer",
+			outputFormat:  "go-template",
+			expectNoMatch: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			printFlags := printers.CustomColumnsPrintFlags{
+				TemplateArgument: tc.templateArg,
+			}
+
+			p, matched, err := printFlags.ToPrinter(tc.outputFormat)
+			if tc.expectNoMatch {
+				if matched {
+					t.Fatalf("expected no printer matches for output format %q", tc.outputFormat)
+				}
+				return
+			}
+			if !matched {
+				t.Fatalf("expected to match template printer for output format %q", tc.outputFormat)
+			}
+
+			if len(tc.expectedError) > 0 {
+				if err == nil || !strings.Contains(err.Error(), tc.expectedError) {
+					t.Errorf("expecting error %q, got %v", tc.expectedError, err)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			out := bytes.NewBuffer([]byte{})
+			err = p.PrintObj(testObject, out)
+			if len(tc.expectedParseError) > 0 {
+				if err == nil || !strings.Contains(err.Error(), tc.expectedParseError) {
+					t.Errorf("expecting error %q, got %v", tc.expectedError, err)
+				}
+				return
+			}
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+			}
+
+			if !strings.Contains(out.String(), tc.expectedOutput) {
+				t.Errorf("unexpected output: expecting %q, got %q", tc.expectedOutput, out.String())
+			}
+		})
+	}
+}

pkg/printers/printers.go

@@ -19,7 +19,6 @@ package printers
 import (
 	"fmt"
 	"io/ioutil"
-	"os"
 
 	"k8s.io/apimachinery/pkg/runtime"
 )
@@ -110,22 +109,21 @@ func GetStandardPrinter(typer runtime.ObjectTyper, encoder runtime.Encoder, deco
 		jsonpathPrinter.AllowMissingKeys(allowMissingTemplateKeys)
 		printer = jsonpathPrinter
 
-	case "custom-columns":
-		var err error
-		if printer, err = NewCustomColumnsPrinterFromSpec(formatArgument, decoders[0], options.NoHeaders); err != nil {
-			return nil, err
+	case "custom-columns", "custom-columns-file":
+		customColumnsFlags := &CustomColumnsPrintFlags{
+			NoHeaders:        options.NoHeaders,
+			TemplateArgument: formatArgument,
 		}
-
-	case "custom-columns-file":
-		file, err := os.Open(formatArgument)
-		if err != nil {
-			return nil, fmt.Errorf("error reading template %s, %v\n", formatArgument, err)
+		customColumnsPrinter, matched, err := customColumnsFlags.ToPrinter(format)
+		if !matched {
+			return nil, fmt.Errorf("unable to match a name printer to handle current print options")
 		}
-		defer file.Close()
-		if printer, err = NewCustomColumnsPrinterFromTemplate(file, decoders[0]); err != nil {
+		if err != nil {
 			return nil, err
 		}
 
+		printer = customColumnsPrinter
+
 	case "wide":
 		fallthrough
 	case "":