gce-containers-startup/utils/welcome-message.go

// Copyright 2017 Google Inc. All Rights Reserved.
//
// 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 (
	"io/ioutil"
	"log"
	"os"
)

const WELCOME_SCRIPT_ON_SUCCESS = `#!/bin/bash
echo -e "\033[0;33m  ########################[ Welcome ]########################\033[0m"
echo -e "\033[0;33m  #  You have logged in to the guest OS.                    #\033[0m"
echo -e "\033[0;33m  #  To access your containers use 'docker attach' command  #\033[0m"
echo -e "\033[0;33m  ###########################################################\033[0m"
echo -e "\033[0;33m                                                             \033[0m"
`

const WELCOME_SCRIPT_ON_FAILURE = `#!/bin/bash
echo -e "\033[0;31m  #########################[ Error ]#########################\033[0m"
echo -e "\033[0;31m  #  The startup agent encountered errors. Your container   #\033[0m"
echo -e "\033[0;31m  #  was not started. To inspect the agent's logs use       #\033[0m"
echo -e "\033[0;31m  #  'sudo journalctl -u konlet-startup' command.           #\033[0m"
echo -e "\033[0;31m  ###########################################################\033[0m"
echo -e "\033[0;31m                                                             \033[0m"
`
const SCRIPT_PATH = "/host/etc/profile.d/gce-containers-welcome.sh"

func WriteWelcomeScript(startupErr interface{}) error {
	script := selectScriptBasedOnStartupResult(startupErr)
	return saveScriptToFile(script, RealFileWriter{}, RealLogger{})
}

func selectScriptBasedOnStartupResult(startupErr interface{}) string {
	if startupErr == nil {
		return WELCOME_SCRIPT_ON_SUCCESS
	} else {
		return WELCOME_SCRIPT_ON_FAILURE
	}
}

func saveScriptToFile(script string, fileWriter FileWriterInterface, logger LoggerInterface) error {
	data := []byte(script)
	writeErr := fileWriter.WriteFile(SCRIPT_PATH, data, 0755)
	if writeErr != nil {
		logger.Print("Failed to save welcome script to profile.d")
		return writeErr
	} else {
		logger.Print("Saving welcome script to profile.d")
		return nil
	}
}

type FileWriterInterface interface {
	WriteFile(filename string, data []byte, perm os.FileMode) error
}

type RealFileWriter struct{}

func (_ RealFileWriter) WriteFile(filename string, data []byte, perm os.FileMode) error {
	return ioutil.WriteFile(filename, data, perm)
}

type LoggerInterface interface {
	Print(v ...interface{})
}

type RealLogger struct{}

func (_ RealLogger) Print(v ...interface{}) {
	log.Print(v...)
}