cloudinit/datasource/proc_cmdline/proc_cmdline.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 proc_cmdline

import (
	"errors"
	"io/ioutil"
	"log"
	"strings"

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

const (
	ProcCmdlineLocation        = "/proc/cmdline"
	ProcCmdlineCloudConfigFlag = "cloud-config-url"
)

type procCmdline struct {
	Location string
}

func NewDatasource() *procCmdline {
	return &procCmdline{Location: ProcCmdlineLocation}
}

func (c *procCmdline) IsAvailable() bool {
	contents, err := ioutil.ReadFile(c.Location)
	if err != nil {
		return false
	}

	cmdline := strings.TrimSpace(string(contents))
	_, err = findCloudConfigURL(cmdline)
	return (err == nil)
}

func (c *procCmdline) AvailabilityChanges() bool {
	return false
}

func (c *procCmdline) ConfigRoot() string {
	return ""
}

func (c *procCmdline) FetchMetadata() ([]byte, error) {
	return []byte{}, nil
}

func (c *procCmdline) FetchUserdata() ([]byte, error) {
	contents, err := ioutil.ReadFile(c.Location)
	if err != nil {
		return nil, err
	}

	cmdline := strings.TrimSpace(string(contents))
	url, err := findCloudConfigURL(cmdline)
	if err != nil {
		return nil, err
	}

	client := pkg.NewHttpClient()
	cfg, err := client.GetRetry(url)
	if err != nil {
		return nil, err
	}

	return cfg, nil
}

func (c *procCmdline) FetchNetworkConfig(filename string) ([]byte, error) {
	return nil, nil
}

func (c *procCmdline) Type() string {
	return "proc-cmdline"
}

func findCloudConfigURL(input string) (url string, err error) {
	err = errors.New("cloud-config-url not found")
	for _, token := range strings.Split(input, " ") {
		parts := strings.SplitN(token, "=", 2)

		key := parts[0]
		key = strings.Replace(key, "_", "-", -1)

		if key != "cloud-config-url" {
			continue
		}

		if len(parts) != 2 {
			log.Printf("Found cloud-config-url in /proc/cmdline with no value, ignoring.")
			continue
		}

		url = parts[1]
		err = nil
	}

	return
}