-
Notifications
You must be signed in to change notification settings - Fork 582
/
commit.go
379 lines (327 loc) · 11 KB
/
commit.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
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
/*
Copyright The containerd Authors.
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 commit
import (
"bytes"
"context"
"crypto/rand"
"encoding/base64"
"encoding/json"
"fmt"
"runtime"
"strings"
"time"
"github.com/containerd/containerd"
"github.com/containerd/containerd/cio"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/diff"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/leases"
"github.com/containerd/containerd/platforms"
"github.com/containerd/containerd/rootfs"
"github.com/containerd/containerd/snapshots"
"github.com/containerd/log"
imgutil "github.com/containerd/nerdctl/pkg/imgutil"
"github.com/containerd/nerdctl/pkg/labels"
"github.com/opencontainers/go-digest"
"github.com/opencontainers/image-spec/identity"
"github.com/opencontainers/image-spec/specs-go"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
)
type Changes struct {
CMD, Entrypoint []string
}
type Opts struct {
Author string
Message string
Ref string
Pause bool
Changes Changes
}
var (
emptyGZLayer = digest.Digest("sha256:4f4fb700ef54461cfa02571ae0db9a0dc1e0cdb5577484a6d75e68dc38e8acc1")
emptyDigest = digest.Digest("")
)
func Commit(ctx context.Context, client *containerd.Client, container containerd.Container, opts *Opts) (digest.Digest, error) {
id := container.ID()
info, err := container.Info(ctx)
if err != nil {
return emptyDigest, err
}
// NOTE: Moby uses provided rootfs to run container. It doesn't support
// to commit container created by moby.
baseImgWithoutPlatform, err := client.ImageService().Get(ctx, info.Image)
if err != nil {
return emptyDigest, fmt.Errorf("container %q lacks image (wasn't created by nerdctl?): %w", id, err)
}
platformLabel := info.Labels[labels.Platform]
if platformLabel == "" {
platformLabel = platforms.DefaultString()
log.G(ctx).Warnf("Image lacks label %q, assuming the platform to be %q", labels.Platform, platformLabel)
}
ocispecPlatform, err := platforms.Parse(platformLabel)
if err != nil {
return emptyDigest, err
}
log.G(ctx).Debugf("ocispecPlatform=%q", platforms.Format(ocispecPlatform))
platformMC := platforms.Only(ocispecPlatform)
baseImg := containerd.NewImageWithPlatform(client, baseImgWithoutPlatform, platformMC)
baseImgConfig, _, err := imgutil.ReadImageConfig(ctx, baseImg)
if err != nil {
return emptyDigest, err
}
task, err := container.Task(ctx, cio.Load)
if err != nil {
return emptyDigest, err
}
if opts.Pause {
status, err := task.Status(ctx)
if err != nil {
return emptyDigest, err
}
switch status.Status {
case containerd.Paused, containerd.Created, containerd.Stopped:
default:
if err := task.Pause(ctx); err != nil {
return emptyDigest, fmt.Errorf("failed to pause container: %w", err)
}
defer func() {
if err := task.Resume(ctx); err != nil {
log.G(ctx).Warnf("failed to unpause container %v: %v", id, err)
}
}()
}
}
var (
differ = client.DiffService()
snName = info.Snapshotter
sn = client.SnapshotService(snName)
)
// Don't gc me and clean the dirty data after 1 hour!
ctx, done, err := client.WithLease(ctx, leases.WithRandomID(), leases.WithExpiration(1*time.Hour))
if err != nil {
return emptyDigest, fmt.Errorf("failed to create lease for commit: %w", err)
}
defer done(ctx)
diffLayerDesc, diffID, err := createDiff(ctx, id, sn, client.ContentStore(), differ)
if err != nil {
return emptyDigest, fmt.Errorf("failed to export layer: %w", err)
}
imageConfig, err := generateCommitImageConfig(ctx, container, baseImg, diffID, opts)
if err != nil {
return emptyDigest, fmt.Errorf("failed to generate commit image config: %w", err)
}
rootfsID := identity.ChainID(imageConfig.RootFS.DiffIDs).String()
if err := applyDiffLayer(ctx, rootfsID, baseImgConfig, sn, differ, diffLayerDesc); err != nil {
return emptyDigest, fmt.Errorf("failed to apply diff: %w", err)
}
commitManifestDesc, configDigest, err := writeContentsForImage(ctx, snName, baseImg, imageConfig, diffLayerDesc)
if err != nil {
return emptyDigest, err
}
// image create
img := images.Image{
Name: opts.Ref,
Target: commitManifestDesc,
CreatedAt: time.Now(),
}
if _, err := client.ImageService().Update(ctx, img); err != nil {
if !errdefs.IsNotFound(err) {
return emptyDigest, err
}
if _, err := client.ImageService().Create(ctx, img); err != nil {
return emptyDigest, fmt.Errorf("failed to create new image %s: %w", opts.Ref, err)
}
}
return configDigest, nil
}
// generateCommitImageConfig returns commit oci image config based on the container's image.
func generateCommitImageConfig(ctx context.Context, container containerd.Container, img containerd.Image, diffID digest.Digest, opts *Opts) (ocispec.Image, error) {
spec, err := container.Spec(ctx)
if err != nil {
return ocispec.Image{}, err
}
baseConfig, _, err := imgutil.ReadImageConfig(ctx, img) // aware of img.platform
if err != nil {
return ocispec.Image{}, err
}
// TODO(fuweid): support updating the USER/ENV/... fields?
if opts.Changes.CMD != nil {
baseConfig.Config.Cmd = opts.Changes.CMD
}
if opts.Changes.Entrypoint != nil {
baseConfig.Config.Entrypoint = opts.Changes.Entrypoint
}
if opts.Author == "" {
opts.Author = baseConfig.Author
}
createdBy := ""
if spec.Process != nil {
createdBy = strings.Join(spec.Process.Args, " ")
}
createdTime := time.Now()
arch := baseConfig.Architecture
if arch == "" {
arch = runtime.GOARCH
log.G(ctx).Warnf("assuming arch=%q", arch)
}
os := baseConfig.OS
if os == "" {
os = runtime.GOOS
log.G(ctx).Warnf("assuming os=%q", os)
}
log.G(ctx).Debugf("generateCommitImageConfig(): arch=%q, os=%q", arch, os)
return ocispec.Image{
Platform: ocispec.Platform{
Architecture: arch,
OS: os,
},
Created: &createdTime,
Author: opts.Author,
Config: baseConfig.Config,
RootFS: ocispec.RootFS{
Type: "layers",
DiffIDs: append(baseConfig.RootFS.DiffIDs, diffID),
},
History: append(baseConfig.History, ocispec.History{
Created: &createdTime,
CreatedBy: createdBy,
Author: opts.Author,
Comment: opts.Message,
EmptyLayer: (diffID == emptyGZLayer),
}),
}, nil
}
// writeContentsForImage will commit oci image config and manifest into containerd's content store.
func writeContentsForImage(ctx context.Context, snName string, baseImg containerd.Image, newConfig ocispec.Image, diffLayerDesc ocispec.Descriptor) (ocispec.Descriptor, digest.Digest, error) {
newConfigJSON, err := json.Marshal(newConfig)
if err != nil {
return ocispec.Descriptor{}, emptyDigest, err
}
configDesc := ocispec.Descriptor{
MediaType: images.MediaTypeDockerSchema2Config,
Digest: digest.FromBytes(newConfigJSON),
Size: int64(len(newConfigJSON)),
}
cs := baseImg.ContentStore()
baseMfst, _, err := imgutil.ReadManifest(ctx, baseImg)
if err != nil {
return ocispec.Descriptor{}, emptyDigest, err
}
layers := append(baseMfst.Layers, diffLayerDesc)
newMfst := struct {
MediaType string `json:"mediaType,omitempty"`
ocispec.Manifest
}{
MediaType: images.MediaTypeDockerSchema2Manifest,
Manifest: ocispec.Manifest{
Versioned: specs.Versioned{
SchemaVersion: 2,
},
Config: configDesc,
Layers: layers,
},
}
newMfstJSON, err := json.MarshalIndent(newMfst, "", " ")
if err != nil {
return ocispec.Descriptor{}, emptyDigest, err
}
newMfstDesc := ocispec.Descriptor{
MediaType: images.MediaTypeDockerSchema2Manifest,
Digest: digest.FromBytes(newMfstJSON),
Size: int64(len(newMfstJSON)),
}
// new manifest should reference the layers and config content
labels := map[string]string{
"containerd.io/gc.ref.content.0": configDesc.Digest.String(),
}
for i, l := range layers {
labels[fmt.Sprintf("containerd.io/gc.ref.content.%d", i+1)] = l.Digest.String()
}
err = content.WriteBlob(ctx, cs, newMfstDesc.Digest.String(), bytes.NewReader(newMfstJSON), newMfstDesc, content.WithLabels(labels))
if err != nil {
return ocispec.Descriptor{}, emptyDigest, err
}
// config should reference to snapshotter
labelOpt := content.WithLabels(map[string]string{
fmt.Sprintf("containerd.io/gc.ref.snapshot.%s", snName): identity.ChainID(newConfig.RootFS.DiffIDs).String(),
})
err = content.WriteBlob(ctx, cs, configDesc.Digest.String(), bytes.NewReader(newConfigJSON), configDesc, labelOpt)
if err != nil {
return ocispec.Descriptor{}, emptyDigest, err
}
return newMfstDesc, configDesc.Digest, nil
}
// createDiff creates a layer diff into containerd's content store.
func createDiff(ctx context.Context, name string, sn snapshots.Snapshotter, cs content.Store, comparer diff.Comparer) (ocispec.Descriptor, digest.Digest, error) {
newDesc, err := rootfs.CreateDiff(ctx, name, sn, comparer)
if err != nil {
return ocispec.Descriptor{}, digest.Digest(""), err
}
info, err := cs.Info(ctx, newDesc.Digest)
if err != nil {
return ocispec.Descriptor{}, digest.Digest(""), err
}
diffIDStr, ok := info.Labels["containerd.io/uncompressed"]
if !ok {
return ocispec.Descriptor{}, digest.Digest(""), fmt.Errorf("invalid differ response with no diffID")
}
diffID, err := digest.Parse(diffIDStr)
if err != nil {
return ocispec.Descriptor{}, digest.Digest(""), err
}
return ocispec.Descriptor{
MediaType: images.MediaTypeDockerSchema2LayerGzip,
Digest: newDesc.Digest,
Size: info.Size,
}, diffID, nil
}
// applyDiffLayer will apply diff layer content created by createDiff into the snapshotter.
func applyDiffLayer(ctx context.Context, name string, baseImg ocispec.Image, sn snapshots.Snapshotter, differ diff.Applier, diffDesc ocispec.Descriptor) (retErr error) {
var (
key = uniquePart() + "-" + name
parent = identity.ChainID(baseImg.RootFS.DiffIDs).String()
)
mount, err := sn.Prepare(ctx, key, parent)
if err != nil {
return err
}
defer func() {
if retErr != nil {
// NOTE: the snapshotter should be hold by lease. Even
// if the cleanup fails, the containerd gc can delete it.
if err := sn.Remove(ctx, key); err != nil {
log.G(ctx).Warnf("failed to cleanup aborted apply %s: %s", key, err)
}
}
}()
if _, err = differ.Apply(ctx, diffDesc, mount); err != nil {
return err
}
if err = sn.Commit(ctx, name, key); err != nil {
if errdefs.IsAlreadyExists(err) {
return nil
}
return err
}
return nil
}
// copied from github.com/containerd/containerd/rootfs/apply.go
func uniquePart() string {
t := time.Now()
var b [3]byte
// Ignore read failures, just decreases uniqueness
rand.Read(b[:])
return fmt.Sprintf("%d-%s", t.Nanosecond(), base64.URLEncoding.EncodeToString(b[:]))
}