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metadata.go
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metadata.go
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// Copyright 2015 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 metadata
import (
"bufio"
"bytes"
"fmt"
"net/http"
"strings"
"github.com/rancher/os/config/cloudinit/pkg"
"github.com/rancher/os/pkg/log"
)
type Service struct {
Root string
Client pkg.Getter
APIVersion string
IsAvailableCheckPath string
UserdataPath string
MetadataPath string
lastError error
}
// NewDatasource creates as HTTP based cloud-data service with the corresponding paths for the user-data and meta-data.
// To check the available in IsAvailable, the apiVersion is used as path.
func NewDatasource(root, apiVersion, userdataPath, metadataPath string, header http.Header) Service {
return NewDatasourceWithCheckPath(root, apiVersion, apiVersion, userdataPath, metadataPath, header)
}
// NewDatasourceWithCheckPath creates as HTTP based cloud-data service with the corresponding paths for the user-data and meta-data.
func NewDatasourceWithCheckPath(root, apiVersion, isAvailableCheckPath, userdataPath, metadataPath string, header http.Header) Service {
if !strings.HasSuffix(root, "/") {
root += "/"
}
return Service{root, pkg.NewHTTPClientHeader(header), apiVersion, isAvailableCheckPath, userdataPath, metadataPath, nil}
}
func (ms Service) IsAvailable() bool {
checkURL := ms.Root + ms.IsAvailableCheckPath
_, ms.lastError = ms.Client.Get(checkURL)
if ms.lastError != nil {
log.Errorf("%s: %s (lastError: %v)", "IsAvailable", checkURL, ms.lastError)
}
return (ms.lastError == nil)
}
func (ms *Service) Finish() error {
return nil
}
func (ms *Service) String() string {
return fmt.Sprintf("%s: %s (lastError: %v)", "metadata", ms.UserdataURL(), ms.lastError)
}
func (ms Service) AvailabilityChanges() bool {
return true
}
func (ms Service) ConfigRoot() string {
return ms.Root
}
func (ms Service) FetchUserdata() ([]byte, error) {
return ms.FetchData(ms.UserdataURL())
}
func (ms Service) FetchData(url string) ([]byte, error) {
if data, err := ms.Client.GetRetry(url); err == nil {
return data, err
} else if _, ok := err.(pkg.ErrNotFound); ok {
return []byte{}, nil
} else {
return data, err
}
}
func (ms Service) MetadataURL() string {
return (ms.Root + ms.MetadataPath)
}
func (ms Service) UserdataURL() string {
return (ms.Root + ms.UserdataPath)
}
func (ms Service) FetchAttributes(key string) ([]string, error) {
url := ms.MetadataURL() + key
resp, err := ms.FetchData(url)
if err != nil {
return nil, err
}
scanner := bufio.NewScanner(bytes.NewBuffer(resp))
data := make([]string, 0)
for scanner.Scan() {
data = append(data, scanner.Text())
}
return data, scanner.Err()
}
func (ms Service) FetchAttribute(key string) (string, error) {
attrs, err := ms.FetchAttributes(key)
if err == nil && len(attrs) > 0 {
return attrs[0], nil
}
return "", err
}