cloudinit/system/etc_hosts.go

/*
   Copyright 2014 CoreOS, 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 system

import (
	"errors"
	"fmt"
	"os"
	"path"

	"github.com/coreos/coreos-cloudinit/config"
)

const DefaultIpv4Address = "127.0.0.1"

type EtcHosts struct {
	Config config.EtcHosts
}

func (eh EtcHosts) generateEtcHosts() (out string, err error) {
	if eh.Config != "localhost" {
		return "", errors.New("Invalid option to manage_etc_hosts")
	}

	// use the operating system hostname
	hostname, err := os.Hostname()
	if err != nil {
		return "", err
	}

	return fmt.Sprintf("%s %s\n", DefaultIpv4Address, hostname), nil

}

func (eh EtcHosts) File() (*File, error) {
	if eh.Config == "" {
		return nil, nil
	}

	etcHosts, err := eh.generateEtcHosts()
	if err != nil {
		return nil, err
	}

	return &File{config.File{
		Path:               path.Join("etc", "hosts"),
		RawFilePermissions: "0644",
		Content:            etcHosts,
	}}, nil
}