teleport/lib/utils/cli.go

/*
Copyright 2016 Gravitational, Inc.

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 utils

import (
	"fmt"
	"io"
	"io/ioutil"
	"log/syslog"
	"os"

	"github.com/gravitational/kingpin"
	"github.com/gravitational/trace"

	log "github.com/Sirupsen/logrus"
	logrusSyslog "github.com/Sirupsen/logrus/hooks/syslog"
)

// CLI tools by default log into syslog, not stderr
func InitLoggerCLI() {
	log.SetLevel(log.InfoLevel)
	// clear existing hooks:
	log.StandardLogger().Hooks = make(log.LevelHooks)
	log.SetFormatter(&trace.TextFormatter{})

	hook, err := logrusSyslog.NewSyslogHook("", "", syslog.LOG_INFO, "")
	if err != nil {
		// syslog not available
		log.Warn("syslog not available. reverting to stderr")
	} else {
		// ... and disable stderr:
		log.AddHook(hook)
		log.SetOutput(ioutil.Discard)
	}
}

// Configures the logger to dump everything to stderr
func InitLoggerDebug() {
	// clear existing hooks:
	log.StandardLogger().Hooks = make(log.LevelHooks)
	log.SetFormatter(&trace.TextFormatter{})
	log.SetOutput(os.Stderr)
	log.SetLevel(log.DebugLevel)
}

// FatalError is for CLI front-ends: it detects gravitational.Trace debugging
// information, sends it to the logger, strips it off and prints a clean message to stderr
func FatalError(err error) {
	var unwrap func(error) error
	unwrap = func(err error) error {
		te, ok := err.(trace.Error)
		if ok {
			return unwrap(te.OrigError())
		}
		return err
	}
	log.Errorf(err.Error())
	fmt.Fprintln(os.Stderr, "Error: "+unwrap(err).Error())
	os.Exit(1)
}

// Consolef prints the same message to a 'ui console' (if defined) and also to
// the logger with INFO priority
func Consolef(w io.Writer, msg string, params ...interface{}) {
	msg = fmt.Sprintf(msg, params...)
	if w != nil {
		fmt.Fprintln(w, msg)
	}
	log.Info(msg)
}

// InitCLIParser configures kingpin command line args parser with
// some defaults common for all Teleport CLI tools
func InitCLIParser(appName, appHelp string) (app *kingpin.Application) {
	app = kingpin.New(appName, appHelp)

	// hide "--help" flag
	app.HelpFlag.Hidden()
	app.HelpFlag.NoEnvar()

	// set our own help template
	return app.UsageTemplate(defaultUsageTemplate)
}

// Usage template with compactly formatted commands.
var defaultUsageTemplate = `{{define "FormatCommand"}}\
{{if .FlagSummary}} {{.FlagSummary}}{{end}}\
{{range .Args}} {{if not .Required}}[{{end}}<{{.Name}}>{{if .Value|IsCumulative}}...{{end}}{{if not .Required}}]{{end}}{{end}}\
{{end}}\

{{define "FormatCommands"}}\
{{range .FlattenedCommands}}\
{{if not .Hidden}}\
  {{.FullCommand | printf "%-12s" }}{{if .Default}}*{{end}} {{ .Help }}
{{end}}\
{{end}}\
{{end}}\

{{define "FormatUsage"}}\
{{template "FormatCommand" .}}{{if .Commands}} <command> [<args> ...]{{end}}
{{if .Help}}
{{.Help|Wrap 0}}\
{{end}}\

{{end}}\

{{if .Context.SelectedCommand}}\
usage: {{.App.Name}} {{.Context.SelectedCommand}}{{template "FormatUsage" .Context.SelectedCommand}}
{{else}}\
Usage: {{.App.Name}}{{template "FormatUsage" .App}}
{{end}}\
{{if .Context.Flags}}\
Flags:
{{.Context.Flags|FlagsToTwoColumnsCompact|FormatTwoColumns}}
{{end}}\
{{if .Context.Args}}\
Args:
{{.Context.Args|ArgsToTwoColumns|FormatTwoColumns}}
{{end}}\
{{if .Context.SelectedCommand}}\

{{ if .Context.SelectedCommand.Commands}}\
Commands:
{{if .Context.SelectedCommand.Commands}}\
{{template "FormatCommands" .Context.SelectedCommand}}
{{end}}\
{{end}}\

{{else if .App.Commands}}\
Commands:
{{template "FormatCommands" .App}}
Try '{{.App.Name}} help [command]' to get help for a given command.
{{end}}\

{{ if .Context.SelectedCommand }}\
{{ range .Context.SelectedCommand.Aliases}}\
{{ . }}
{{end}}\
{{end}}
`