/
metadata.go
326 lines (286 loc) · 10.6 KB
/
metadata.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
/*
Copyright 2015 The Kubernetes Authors 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 metadata
import (
"io/ioutil"
"os"
"path"
"path/filepath"
"sort"
"strings"
"time"
"github.com/golang/glog"
"k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/fieldpath"
"k8s.io/kubernetes/pkg/types"
"k8s.io/kubernetes/pkg/util"
utilErrors "k8s.io/kubernetes/pkg/util/errors"
"k8s.io/kubernetes/pkg/util/mount"
"k8s.io/kubernetes/pkg/volume"
)
// ProbeVolumePlugins is the entry point for plugin detection in a package.
func ProbeVolumePlugins() []volume.VolumePlugin {
return []volume.VolumePlugin{&metadataPlugin{}}
}
const (
metadataPluginName = "kubernetes.io/metadata"
)
// metadataPlugin implements the VolumePlugin interface.
type metadataPlugin struct {
host volume.VolumeHost
}
func (plugin *metadataPlugin) Init(host volume.VolumeHost) {
plugin.host = host
}
func (plugin *metadataPlugin) Name() string {
return metadataPluginName
}
func (plugin *metadataPlugin) CanSupport(spec *volume.Spec) bool {
return spec.Volume != nil && spec.Volume.VolumeSource.Metadata != nil
}
func (plugin *metadataPlugin) NewBuilder(spec *volume.Spec, pod *api.Pod, opts volume.VolumeOptions, mounter mount.Interface) (volume.Builder, error) {
return plugin.newBuilderInternal(spec, pod, opts, mounter)
}
func (plugin *metadataPlugin) newBuilderInternal(spec *volume.Spec, pod *api.Pod, opts volume.VolumeOptions, mounter mount.Interface) (volume.Builder, error) {
v := &metadataVolume{volName: spec.Name(),
pod: pod,
plugin: plugin,
opts: &opts,
mounter: mounter}
v.fieldReferenceFileNames = make(map[string]string)
for _, fileInfo := range spec.Volume.VolumeSource.Metadata.Items {
v.fieldReferenceFileNames[fileInfo.FieldRef.FieldPath] = fileInfo.Name
}
return v, nil
}
func (plugin *metadataPlugin) NewCleaner(volName string, podUID types.UID, mounter mount.Interface) (volume.Cleaner, error) {
return plugin.newCleanerInternal(volName, podUID, mounter)
}
func (plugin *metadataPlugin) newCleanerInternal(volName string, podUID types.UID, mounter mount.Interface) (volume.Cleaner, error) {
return &metadataVolume{volName: volName,
pod: &api.Pod{ObjectMeta: api.ObjectMeta{UID: podUID}},
plugin: plugin,
mounter: mounter}, nil
}
// metadataVolume handles retrieving metadata from the API server
// and placing them into the volume on the host.
type metadataVolume struct {
volName string
fieldReferenceFileNames map[string]string
pod *api.Pod
plugin *metadataPlugin
opts *volume.VolumeOptions
mounter mount.Interface
}
// This is the spec for the volume that this plugin wraps.
var wrappedVolumeSpec = &volume.Spec{
Volume: &api.Volume{VolumeSource: api.VolumeSource{EmptyDir: &api.EmptyDirVolumeSource{Medium: api.StorageMediumMemory}}},
}
// IsReadOnly exposes if the volume is read only.
// TODO: is this ok to always return true?
func (m *metadataVolume) IsReadOnly() bool {
return true
}
// SetUp puts in place the volume plugin.
// This function is not idempotent by design. We want the data to be refreshed periodically.
// The internal sync interval of kubelet will drive the refresh of data.
func (m *metadataVolume) SetUp() error {
return m.SetUpAt(m.GetPath())
}
func (m *metadataVolume) SetUpAt(dir string) error {
glog.V(3).Infof("Setting up a metadata volume %v for pod %v at %v", m.volName, m.pod.UID, dir)
// Wrap EmptyDir,let it do the setup.
wrapped, err := m.plugin.host.NewWrapperBuilder(wrappedVolumeSpec, m.pod, *m.opts, m.mounter)
if err != nil {
return err
}
if err := wrapped.SetUpAt(dir); err != nil {
return err
}
data := make(map[string]string)
if err := m.collectData(&data); err != nil {
return err
}
// files are fully regenerated only if requested metadata changed
if m.isDataChanged(&data) {
err = m.writeData(&data)
}
return err
}
// collectData collects requested metadata in data map.
// Map's key is the requested name of file to dump
// Map's value is the (sorted) content of the field to be dumped in the file.
func (m *metadataVolume) collectData(data *map[string]string) error {
errlist := []error{}
for fieldReference, fileName := range m.fieldReferenceFileNames {
if values, err := fieldpath.ExtractFieldPathAsString(m.pod, fieldReference); err != nil {
glog.Error(err)
errlist = append(errlist, err)
} else {
(*data)[fileName] = sortLines(values)
}
}
return utilErrors.NewAggregate(errlist)
}
// isDataChanged iterate over all the entries to check wether at least one
// file needs to be updated.
func (m *metadataVolume) isDataChanged(data *map[string]string) bool {
for fileName, values := range *data {
if isFileToGenerate(path.Join(m.GetPath(), fileName), values) {
return true
}
}
return false
}
// isFileToGenerate compares actual file with the new values. If
// different (or the file does not exist) return true
func isFileToGenerate(fileName, values string) bool {
if _, err := os.Lstat(fileName); os.IsNotExist(err) {
return true
}
return readFile(fileName) != values
}
const currentDir = ".current"
const currentTmpDir = ".current_tmp"
// writeData writes requested metadata in specified files.
//
// The file visible in this volume are symlinks to files in the '.current'
// directory. Actual files are stored in an hidden timestamped directory which is
// symlinked to by '.current'. The timestamped directory and '.current' symlink
// are created in the plugin root dir. This scheme allows the files to be
// atomically updated by changing the target of the '.current' symlink. When new
// data is available:
//
// 1. A new timestamped dir is created by writeDataInTimestampDir
// 2. Symlinks for new files are created if needed
// 3. The previous timestamped directory is detected reading the '.current' symlink
// 4. In case no symlink exists then it's created and func returns (first execution)
// 5. In case symlink exists a new temporary symlink is created .current_tmp
// 6. .current_tmp is renamed to .current
// 7. The previous timestamped directory is removed
func (m *metadataVolume) writeData(data *map[string]string) error {
var timestampDir string
var err error
timestampDir, err = m.writeDataInTimestampDir(data)
if err != nil {
glog.Error(err)
return err
}
// update symbolic links for relative paths
if err = m.updateSymlinksToCurrentDir(); err != nil {
os.RemoveAll(timestampDir)
glog.Error(err)
return err
}
_, timestampDirBaseName := filepath.Split(timestampDir)
var oldTimestampDirectory string
oldTimestampDirectory, err = os.Readlink(path.Join(m.GetPath(), currentDir))
if err != nil {
if os.IsNotExist(err) { // no link to currentDir so creates it
err = os.Symlink(timestampDirBaseName, path.Join(m.GetPath(), currentDir))
}
return err // in any cases return
}
// nominal case: link to currentDir exists create the link to currentTmpDir
if err = os.Symlink(timestampDirBaseName, path.Join(m.GetPath(), currentTmpDir)); err != nil {
os.RemoveAll(timestampDir)
glog.Error(err)
return err
}
// Rename the symbolic link currentTmpDir to currentDir
if err = os.Rename(path.Join(m.GetPath(), currentTmpDir), path.Join(m.GetPath(), currentDir)); err != nil {
// in case of error remove latest data and currentTmpDir
os.Remove(path.Join(m.GetPath(), currentTmpDir))
os.RemoveAll(timestampDir)
glog.Error(err)
return err
}
// Remove oldTimestampDirectory
if len(oldTimestampDirectory) > 0 {
if e := os.RemoveAll(path.Join(m.GetPath(), oldTimestampDirectory)); e != nil {
glog.Error(e)
return e
}
}
return nil
}
// writeDataInTimestampDir writes the latest data into a new temporary directory with a timestamp.
func (m *metadataVolume) writeDataInTimestampDir(data *map[string]string) (string, error) {
errlist := []error{}
timestampDir, err := ioutil.TempDir(m.GetPath(), "."+time.Now().Format("2006_01_02_15_04_05"))
for fileName, values := range *data {
fullPathFile := path.Join(timestampDir, fileName)
dir, _ := filepath.Split(fullPathFile)
if err = os.MkdirAll(dir, os.ModePerm); err != nil {
return "", err
}
if e := ioutil.WriteFile(fullPathFile, []byte(values), 0644); e != nil {
glog.Error(e)
errlist = append(errlist, err)
}
}
return timestampDir, utilErrors.NewAggregate(errlist)
}
// updateSymlinksToCurrentDir creates the relative symlinks for all the files configured in this volume.
// If the directory in a file path does not exist, it is created.
func (m *metadataVolume) updateSymlinksToCurrentDir() error {
for _, f := range m.fieldReferenceFileNames {
dir, _ := filepath.Split(f)
nbOfSubdir := 0
if len(dir) > 0 {
nbOfSubdir = len(strings.Split(dir, "/")) - 1
if e := os.MkdirAll(path.Join(m.GetPath(), dir), os.ModePerm); e != nil {
return e
}
}
if _, e := os.Readlink(path.Join(m.GetPath(), f)); e != nil {
// link does not exist create it
if e := os.Symlink(path.Join(strings.Repeat("../", nbOfSubdir)+currentDir, f), path.Join(m.GetPath(), f)); e != nil {
return e
}
}
}
return nil
}
// readFile reads the file at the given path and returns the content as a string.
func readFile(path string) string {
if data, err := ioutil.ReadFile(path); err == nil {
return string(data)
}
return ""
}
// sortLines sorts the strings generated from map based metadata
// (annotations and labels)
func sortLines(values string) string {
splitted := strings.Split(values, "\n")
sort.Strings(splitted)
return strings.Join(splitted, "\n")
}
func (m *metadataVolume) GetPath() string {
return m.plugin.host.GetPodVolumeDir(m.pod.UID, util.EscapeQualifiedNameForDisk(metadataPluginName), m.volName)
}
func (m *metadataVolume) TearDown() error {
return m.TearDownAt(m.GetPath())
}
func (m *metadataVolume) TearDownAt(dir string) error {
glog.V(3).Infof("Tearing down volume %v for pod %v at %v", m.volName, m.pod.UID, dir)
// Wrap EmptyDir, let it do the teardown.
wrapped, err := m.plugin.host.NewWrapperCleaner(wrappedVolumeSpec, m.pod.UID, m.mounter)
if err != nil {
return err
}
return wrapped.TearDownAt(dir)
}
func (m *metadataVolume) getMetaDir() string {
return path.Join(m.plugin.host.GetPodPluginDir(m.pod.UID, util.EscapeQualifiedNameForDisk(metadataPluginName)), m.volName)
}