forked from moby/moby
-
Notifications
You must be signed in to change notification settings - Fork 0
/
image.go
274 lines (255 loc) · 6.8 KB
/
image.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
package docker
import (
"crypto/rand"
"encoding/hex"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"os/exec"
"path"
"strings"
"time"
)
type Image struct {
Id string `json:"id"`
Parent string `json:"parent,omitempty"`
Comment string `json:"comment,omitempty"`
Created time.Time `json:"created"`
Container string `json:"container,omitempty"`
ContainerConfig Config `json:"container_config,omitempty"`
DockerVersion string `json:"docker_version,omitempty"`
Author string `json:"author,omitempty"`
graph *Graph
}
func LoadImage(root string) (*Image, error) {
// Load the json data
jsonData, err := ioutil.ReadFile(jsonPath(root))
if err != nil {
return nil, err
}
var img Image
if err := json.Unmarshal(jsonData, &img); err != nil {
return nil, err
}
if err := ValidateId(img.Id); err != nil {
return nil, err
}
// Check that the filesystem layer exists
if stat, err := os.Stat(layerPath(root)); err != nil {
if os.IsNotExist(err) {
return nil, fmt.Errorf("Couldn't load image %s: no filesystem layer", img.Id)
} else {
return nil, err
}
} else if !stat.IsDir() {
return nil, fmt.Errorf("Couldn't load image %s: %s is not a directory", img.Id, layerPath(root))
}
return &img, nil
}
func StoreImage(img *Image, layerData Archive, root string) error {
// Check that root doesn't already exist
if _, err := os.Stat(root); err == nil {
return fmt.Errorf("Image %s already exists", img.Id)
} else if !os.IsNotExist(err) {
return err
}
// Store the layer
layer := layerPath(root)
if err := os.MkdirAll(layer, 0700); err != nil {
return err
}
if err := Untar(layerData, layer); err != nil {
return err
}
// Store the json ball
jsonData, err := json.Marshal(img)
if err != nil {
return err
}
if err := ioutil.WriteFile(jsonPath(root), jsonData, 0600); err != nil {
return err
}
return nil
}
func layerPath(root string) string {
return path.Join(root, "layer")
}
func jsonPath(root string) string {
return path.Join(root, "json")
}
func MountAUFS(ro []string, rw string, target string) error {
// FIXME: Now mount the layers
rwBranch := fmt.Sprintf("%v=rw", rw)
roBranches := ""
for _, layer := range ro {
roBranches += fmt.Sprintf("%v=ro:", layer)
}
branches := fmt.Sprintf("br:%v:%v", rwBranch, roBranches)
//if error, try to load aufs kernel module
if err := mount("none", target, "aufs", 0, branches); err != nil {
log.Printf("Kernel does not support AUFS, trying to load the AUFS module with modprobe...")
if err := exec.Command("modprobe", "aufs").Run(); err != nil {
return fmt.Errorf("Unable to load the AUFS module")
}
log.Printf("...module loaded.")
if err := mount("none", target, "aufs", 0, branches); err != nil {
return fmt.Errorf("Unable to mount using aufs")
}
}
return nil
}
func (image *Image) Mount(root, rw string) error {
if mounted, err := Mounted(root); err != nil {
return err
} else if mounted {
return fmt.Errorf("%s is already mounted", root)
}
layers, err := image.layers()
if err != nil {
return err
}
// Create the target directories if they don't exist
if err := os.Mkdir(root, 0755); err != nil && !os.IsExist(err) {
return err
}
if err := os.Mkdir(rw, 0755); err != nil && !os.IsExist(err) {
return err
}
// FIXME: @creack shouldn't we do this after going over changes?
if err := MountAUFS(layers, rw, root); err != nil {
return err
}
// FIXME: Create tests for deletion
// FIXME: move this part to change.go
// Retrieve the changeset from the parent and apply it to the container
// - Retrieve the changes
changes, err := Changes(layers, layers[0])
if err != nil {
return err
}
// Iterate on changes
for _, c := range changes {
// If there is a delete
if c.Kind == ChangeDelete {
// Make sure the directory exists
file_path, file_name := path.Dir(c.Path), path.Base(c.Path)
if err := os.MkdirAll(path.Join(rw, file_path), 0755); err != nil {
return err
}
// And create the whiteout (we just need to create empty file, discard the return)
if _, err := os.Create(path.Join(path.Join(rw, file_path),
".wh."+path.Base(file_name))); err != nil {
return err
}
}
}
return nil
}
func (image *Image) Changes(rw string) ([]Change, error) {
layers, err := image.layers()
if err != nil {
return nil, err
}
return Changes(layers, rw)
}
func (image *Image) ShortId() string {
return TruncateId(image.Id)
}
func ValidateId(id string) error {
if id == "" {
return fmt.Errorf("Image id can't be empty")
}
if strings.Contains(id, ":") {
return fmt.Errorf("Invalid character in image id: ':'")
}
return nil
}
func GenerateId() string {
id := make([]byte, 32)
_, err := io.ReadFull(rand.Reader, id)
if err != nil {
panic(err) // This shouldn't happen
}
return hex.EncodeToString(id)
}
// Image includes convenience proxy functions to its graph
// These functions will return an error if the image is not registered
// (ie. if image.graph == nil)
func (img *Image) History() ([]*Image, error) {
var parents []*Image
if err := img.WalkHistory(
func(img *Image) error {
parents = append(parents, img)
return nil
},
); err != nil {
return nil, err
}
return parents, nil
}
// layers returns all the filesystem layers needed to mount an image
// FIXME: @shykes refactor this function with the new error handling
// (I'll do it if I have time tonight, I focus on the rest)
func (img *Image) layers() ([]string, error) {
var list []string
var e error
if err := img.WalkHistory(
func(img *Image) (err error) {
if layer, err := img.layer(); err != nil {
e = err
} else if layer != "" {
list = append(list, layer)
}
return err
},
); err != nil {
return nil, err
} else if e != nil { // Did an error occur inside the handler?
return nil, e
}
if len(list) == 0 {
return nil, fmt.Errorf("No layer found for image %s\n", img.Id)
}
return list, nil
}
func (img *Image) WalkHistory(handler func(*Image) error) (err error) {
currentImg := img
for currentImg != nil {
if handler != nil {
if err := handler(currentImg); err != nil {
return err
}
}
currentImg, err = currentImg.GetParent()
if err != nil {
return fmt.Errorf("Error while getting parent image: %v", err)
}
}
return nil
}
func (img *Image) GetParent() (*Image, error) {
if img.Parent == "" {
return nil, nil
}
if img.graph == nil {
return nil, fmt.Errorf("Can't lookup parent of unregistered image")
}
return img.graph.Get(img.Parent)
}
func (img *Image) root() (string, error) {
if img.graph == nil {
return "", fmt.Errorf("Can't lookup root of unregistered image")
}
return img.graph.imageRoot(img.Id), nil
}
// Return the path of an image's layer
func (img *Image) layer() (string, error) {
root, err := img.root()
if err != nil {
return "", err
}
return layerPath(root), nil
}