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
|
// Google Cloud Storage backend for Nixery.
package storage
import (
"context"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"os"
"time"
"cloud.google.com/go/storage"
log "github.com/sirupsen/logrus"
"golang.org/x/oauth2/google"
)
// HTTP client to use for direct calls to APIs that are not part of the SDK
var client = &http.Client{}
// API scope needed for renaming objects in GCS
const gcsScope = "https://www.googleapis.com/auth/devstorage.read_write"
type GCSBackend struct {
bucket string
handle *storage.BucketHandle
signing *storage.SignedURLOptions
}
// Constructs a new GCS bucket backend based on the configured
// environment variables.
func NewGCSBackend() (*GCSBackend, error) {
bucket := os.Getenv("GCS_BUCKET")
if bucket == "" {
return nil, fmt.Errorf("GCS_BUCKET must be configured for GCS usage")
}
ctx := context.Background()
client, err := storage.NewClient(ctx)
if err != nil {
log.WithError(err).Fatal("failed to set up Cloud Storage client")
}
handle := client.Bucket(bucket)
if _, err := handle.Attrs(ctx); err != nil {
log.WithError(err).WithField("bucket", bucket).Error("could not access configured bucket")
return nil, err
}
signing, err := signingOptsFromEnv()
if err != nil {
log.WithError(err).Error("failed to configure GCS bucket signing")
return nil, err
}
return &GCSBackend{
bucket: bucket,
handle: handle,
signing: signing,
}, nil
}
func (b *GCSBackend) Name() string {
return "Google Cloud Storage (" + b.bucket + ")"
}
func (b *GCSBackend) Persist(ctx context.Context, path string, f Persister) (string, int64, error) {
obj := b.handle.Object(path)
w := obj.NewWriter(ctx)
hash, size, err := f(w)
if err != nil {
log.WithError(err).WithField("path", path).Error("failed to upload to GCS")
return hash, size, err
}
return hash, size, w.Close()
}
func (b *GCSBackend) Fetch(ctx context.Context, path string) (io.ReadCloser, error) {
obj := b.handle.Object(path)
// Probe whether the file exists before trying to fetch it
_, err := obj.Attrs(ctx)
if err != nil {
return nil, err
}
return obj.NewReader(ctx)
}
// renameObject renames an object in the specified Cloud Storage
// bucket.
//
// The Go API for Cloud Storage does not support renaming objects, but
// the HTTP API does. The code below makes the relevant call manually.
func (b *GCSBackend) Move(ctx context.Context, old, new string) error {
creds, err := google.FindDefaultCredentials(ctx, gcsScope)
if err != nil {
return err
}
token, err := creds.TokenSource.Token()
if err != nil {
return err
}
// as per https://cloud.google.com/storage/docs/renaming-copying-moving-objects#rename
url := fmt.Sprintf(
"https://www.googleapis.com/storage/v1/b/%s/o/%s/rewriteTo/b/%s/o/%s",
url.PathEscape(b.bucket), url.PathEscape(old),
url.PathEscape(b.bucket), url.PathEscape(new),
)
req, err := http.NewRequest("POST", url, nil)
req.Header.Add("Authorization", "Bearer "+token.AccessToken)
_, err = client.Do(req)
if err != nil {
return err
}
// It seems that 'rewriteTo' copies objects instead of
// renaming/moving them, hence a deletion call afterwards is
// required.
if err = b.handle.Object(old).Delete(ctx); err != nil {
log.WithError(err).WithFields(log.Fields{
"new": new,
"old": old,
}).Warn("failed to delete renamed object")
// this error should not break renaming and is not returned
}
return nil
}
func (b *GCSBackend) ServeLayer(digest string, r *http.Request, w http.ResponseWriter) error {
url, err := b.constructLayerUrl(digest)
if err != nil {
log.WithError(err).WithFields(log.Fields{
"layer": digest,
"bucket": b.bucket,
}).Error("failed to sign GCS URL")
return err
}
log.WithField("layer", digest).Info("redirecting layer request to GCS bucket")
w.Header().Set("Location", url)
w.WriteHeader(303)
return nil
}
// Configure GCS URL signing in the presence of a service account key
// (toggled if the user has set GOOGLE_APPLICATION_CREDENTIALS).
func signingOptsFromEnv() (*storage.SignedURLOptions, error) {
path := os.Getenv("GOOGLE_APPLICATION_CREDENTIALS")
if path == "" {
// No credentials configured -> no URL signing
return nil, nil
}
key, err := ioutil.ReadFile(path)
if err != nil {
return nil, fmt.Errorf("failed to read service account key: %s", err)
}
conf, err := google.JWTConfigFromJSON(key)
if err != nil {
return nil, fmt.Errorf("failed to parse service account key: %s", err)
}
log.WithField("account", conf.Email).Info("GCS URL signing enabled")
return &storage.SignedURLOptions{
Scheme: storage.SigningSchemeV4,
GoogleAccessID: conf.Email,
PrivateKey: conf.PrivateKey,
Method: "GET",
}, nil
}
// layerRedirect constructs the public URL of the layer object in the Cloud
// Storage bucket, signs it and redirects the user there.
//
// Signing the URL allows unauthenticated clients to retrieve objects from the
// bucket.
//
// The Docker client is known to follow redirects, but this might not be true
// for all other registry clients.
func (b *GCSBackend) constructLayerUrl(digest string) (string, error) {
log.WithField("layer", digest).Info("redirecting layer request to bucket")
object := "layers/" + digest
if b.signing != nil {
opts := *b.signing
opts.Expires = time.Now().Add(5 * time.Minute)
return storage.SignedURL(b.bucket, object, &opts)
} else {
return ("https://storage.googleapis.com/" + b.bucket + "/" + object), nil
}
}
|
