printing.go

/*
Copyright 2014 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 util

import (
	"fmt"
	"io"
	"strings"

	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/kubernetes/pkg/kubectl"
	"k8s.io/kubernetes/pkg/kubectl/resource"

	"github.com/spf13/cobra"
)

// AddPrinterFlags adds printing related flags to a command (e.g. output format, no headers, template path)
func AddPrinterFlags(cmd *cobra.Command) {
	AddOutputFlags(cmd)
	cmd.Flags().String("output-version", "", "Output the formatted object with the given group version (for ex: 'extensions/v1beta1').")
	AddNoHeadersFlags(cmd)
	cmd.Flags().Bool("show-labels", false, "When printing, show all labels as the last column (default hide labels column)")
	cmd.Flags().String("template", "", "Template string or path to template file to use when -o=go-template, -o=go-template-file. The template format is golang templates [http://golang.org/pkg/text/template/#pkg-overview].")
	cmd.MarkFlagFilename("template")
	cmd.Flags().String("sort-by", "", "If non-empty, sort list types using this field specification.  The field specification is expressed as a JSONPath expression (e.g. '{.metadata.name}'). The field in the API resource specified by this JSONPath expression must be an integer or a string.")
	cmd.Flags().BoolP("show-all", "a", false, "When printing, show all resources (default hide terminated pods.)")
}

// AddOutputFlagsForMutation adds output related flags to a command. Used by mutations only.
func AddOutputFlagsForMutation(cmd *cobra.Command) {
	cmd.Flags().StringP("output", "o", "", "Output mode. Use \"-o name\" for shorter output (resource/name).")
}

// AddOutputVarFlagsForMutation adds output related flags to a command. Used by mutations only.
func AddOutputVarFlagsForMutation(cmd *cobra.Command, output *string) {
	cmd.Flags().StringVarP(output, "output", "o", "", "Output mode. Use \"-o name\" for shorter output (resource/name).")
}

// 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.
func AddNoHeadersFlags(cmd *cobra.Command) {
	cmd.Flags().Bool("no-headers", false, "When using the default or custom-column output format, don't print headers (default print headers).")
}

// PrintSuccess prints message after finishing mutating operations
func PrintSuccess(mapper meta.RESTMapper, shortOutput bool, out io.Writer, resource string, name string, dryRun bool, operation string) {
	resource, _ = mapper.ResourceSingularizer(resource)
	dryRunMsg := ""
	if dryRun {
		dryRunMsg = " (dry run)"
	}
	if shortOutput {
		// -o name: prints resource/name
		if len(resource) > 0 {
			fmt.Fprintf(out, "%s/%s\n", resource, name)
		} else {
			fmt.Fprintf(out, "%s\n", name)
		}
	} else {
		// understandable output by default
		if len(resource) > 0 {
			fmt.Fprintf(out, "%s \"%s\" %s%s\n", resource, name, operation, dryRunMsg)
		} else {
			fmt.Fprintf(out, "\"%s\" %s%s\n", name, operation, dryRunMsg)
		}
	}
}

// ValidateOutputArgs validates -o flag args for mutations
func ValidateOutputArgs(cmd *cobra.Command) error {
	outputMode := GetFlagString(cmd, "output")
	if outputMode != "" && outputMode != "name" {
		return UsageError(cmd, "Unexpected -o output mode: %v. We only support '-o name'.", outputMode)
	}
	return nil
}

// OutputVersion returns the preferred output version for generic content (JSON, YAML, or templates)
// defaultVersion is never mutated.  Nil simply allows clean passing in common usage from client.Config
func OutputVersion(cmd *cobra.Command, defaultVersion *schema.GroupVersion) (schema.GroupVersion, error) {
	outputVersionString := GetFlagString(cmd, "output-version")
	if len(outputVersionString) == 0 {
		if defaultVersion == nil {
			return schema.GroupVersion{}, nil
		}

		return *defaultVersion, nil
	}

	return schema.ParseGroupVersion(outputVersionString)
}

// PrinterForCommand returns the default printer for this command.
// Requires that printer flags have been added to cmd (see AddPrinterFlags).
func PrinterForCommand(cmd *cobra.Command) (kubectl.ResourcePrinter, bool, error) {
	outputFormat := GetFlagString(cmd, "output")

	// templates are logically optional for specifying a format.
	// TODO once https://github.com/kubernetes/kubernetes/issues/12668 is fixed, this should fall back to GetFlagString
	templateFile, _ := cmd.Flags().GetString("template")
	if len(outputFormat) == 0 && len(templateFile) != 0 {
		outputFormat = "template"
	}

	templateFormat := []string{
		"go-template=", "go-template-file=", "jsonpath=", "jsonpath-file=", "custom-columns=", "custom-columns-file=",
	}
	for _, format := range templateFormat {
		if strings.HasPrefix(outputFormat, format) {
			templateFile = outputFormat[len(format):]
			outputFormat = format[:len(format)-1]
		}
	}

	// 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
	}

	return maybeWrapSortingPrinter(cmd, printer), generic, nil
}

// PrintResourceInfoForCommand receives a *cobra.Command and a *resource.Info and
// attempts to print an info object based on the specified output format. If the
// object passed is non-generic, it attempts to print the object using a HumanReadablePrinter.
// Requires that printer flags have been added to cmd (see AddPrinterFlags).
func PrintResourceInfoForCommand(cmd *cobra.Command, info *resource.Info, f Factory, out io.Writer) error {
	printer, generic, err := PrinterForCommand(cmd)
	if err != nil {
		return err
	}
	if !generic || printer == nil {
		printer, err = f.PrinterForMapping(cmd, nil, false)
		if err != nil {
			return err
		}
	}
	return printer.PrintObj(info.Object, out)
}

func maybeWrapSortingPrinter(cmd *cobra.Command, printer kubectl.ResourcePrinter) kubectl.ResourcePrinter {
	sorting, err := cmd.Flags().GetString("sort-by")
	if err != nil {
		// error can happen on missing flag or bad flag type.  In either case, this command didn't intent to sort
		return printer
	}

	if len(sorting) != 0 {
		return &kubectl.SortingPrinter{
			Delegate:  printer,
			SortField: fmt.Sprintf("{%s}", sorting),
		}
	}
	return printer
}