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 (
	"crypto/x509"
	"fmt"
	"io"
	"io/ioutil"
	"log/syslog"
	"os"
	"strconv"

	"github.com/gravitational/teleport"

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

type LoggingPurpose int

const (
	LoggingForDaemon LoggingPurpose = iota
	LoggingForCLI
	LoggingForTests
)

// InitLogger configures the global logger for a given purpose / verbosity level
func InitLogger(purpose LoggingPurpose, level log.Level) {
	log.StandardLogger().Hooks = make(log.LevelHooks)
	formatter := &trace.TextFormatter{}
	formatter.DisableTimestamp = true
	log.SetFormatter(formatter)
	log.SetLevel(level)

	switch purpose {
	case LoggingForCLI:
		SwitchLoggingtoSyslog()
	case LoggingForDaemon:
		log.SetOutput(os.Stderr)
	case LoggingForTests:
		log.SetLevel(level)
		val, _ := strconv.ParseBool(os.Getenv(teleport.VerboseLogsEnvVar))
		if val {
			return
		}
		log.SetLevel(log.WarnLevel)
		log.SetOutput(ioutil.Discard)
	}
}

func InitLoggerForTests() {
	InitLogger(LoggingForTests, log.WarnLevel)
}

// SwitchLoggingtoSyslog tells the logger to send the output to syslog
func SwitchLoggingtoSyslog() {
	log.StandardLogger().Hooks = make(log.LevelHooks)
	hook, err := logrusSyslog.NewSyslogHook("", "", syslog.LOG_WARNING, "")
	if err != nil {
		// syslog not available
		log.SetOutput(os.Stderr)
		log.Warn("syslog not available. reverting to stderr")
	} else {
		// ... and disable stderr:
		log.AddHook(hook)
		log.SetOutput(ioutil.Discard)
	}
}

// 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) {
	fmt.Fprintln(os.Stderr, UserMessageFromError(err))
	os.Exit(1)
}

// UserMessageFromError returns user friendly error message from error
func UserMessageFromError(err error) string {
	// untrusted cert?
	switch innerError := trace.Unwrap(err).(interface{}).(type) {
	case x509.HostnameError:
		return fmt.Sprintf("Cannot establish https connection to %s:\n%s\n%s\n",
			innerError.Host,
			innerError.Error(),
			"try a different hostname for --proxy or specify --insecure flag if you know what you're doing.")
	case x509.UnknownAuthorityError, x509.CertificateInvalidError:
		return "WARNING:\n The proxy you are connecting to uses the self-signed HTTPS certificate.\n" +
			" Try --insecure flag if you know what you're doing.\n"
	}
	if log.GetLevel() == log.DebugLevel {
		return trace.DebugReport(err)
	}
	return err.Error()
}

// 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}} (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}}
`