github.com/adxhyt/docker@v1.4.2-0.20150117221845-467b7c821390/graph/graph.go (about) 1 package graph 2 3 import ( 4 "fmt" 5 "io" 6 "io/ioutil" 7 "os" 8 "path" 9 "path/filepath" 10 "runtime" 11 "strings" 12 "syscall" 13 "time" 14 15 log "github.com/Sirupsen/logrus" 16 "github.com/docker/docker/daemon/graphdriver" 17 "github.com/docker/docker/dockerversion" 18 "github.com/docker/docker/image" 19 "github.com/docker/docker/pkg/archive" 20 "github.com/docker/docker/pkg/truncindex" 21 "github.com/docker/docker/runconfig" 22 "github.com/docker/docker/utils" 23 ) 24 25 // A Graph is a store for versioned filesystem images and the relationship between them. 26 type Graph struct { 27 Root string 28 idIndex *truncindex.TruncIndex 29 driver graphdriver.Driver 30 } 31 32 // NewGraph instantiates a new graph at the given root path in the filesystem. 33 // `root` will be created if it doesn't exist. 34 func NewGraph(root string, driver graphdriver.Driver) (*Graph, error) { 35 abspath, err := filepath.Abs(root) 36 if err != nil { 37 return nil, err 38 } 39 // Create the root directory if it doesn't exists 40 if err := os.MkdirAll(root, 0700); err != nil && !os.IsExist(err) { 41 return nil, err 42 } 43 44 graph := &Graph{ 45 Root: abspath, 46 idIndex: truncindex.NewTruncIndex([]string{}), 47 driver: driver, 48 } 49 if err := graph.restore(); err != nil { 50 return nil, err 51 } 52 return graph, nil 53 } 54 55 func (graph *Graph) restore() error { 56 dir, err := ioutil.ReadDir(graph.Root) 57 if err != nil { 58 return err 59 } 60 var ids = []string{} 61 for _, v := range dir { 62 id := v.Name() 63 if graph.driver.Exists(id) { 64 ids = append(ids, id) 65 } 66 } 67 graph.idIndex = truncindex.NewTruncIndex(ids) 68 log.Debugf("Restored %d elements", len(dir)) 69 return nil 70 } 71 72 // FIXME: Implement error subclass instead of looking at the error text 73 // Note: This is the way golang implements os.IsNotExists on Plan9 74 func (graph *Graph) IsNotExist(err error) bool { 75 return err != nil && (strings.Contains(strings.ToLower(err.Error()), "does not exist") || strings.Contains(strings.ToLower(err.Error()), "no such")) 76 } 77 78 // Exists returns true if an image is registered at the given id. 79 // If the image doesn't exist or if an error is encountered, false is returned. 80 func (graph *Graph) Exists(id string) bool { 81 if _, err := graph.Get(id); err != nil { 82 return false 83 } 84 return true 85 } 86 87 // Get returns the image with the given id, or an error if the image doesn't exist. 88 func (graph *Graph) Get(name string) (*image.Image, error) { 89 id, err := graph.idIndex.Get(name) 90 if err != nil { 91 return nil, fmt.Errorf("could not find image: %v", err) 92 } 93 img, err := image.LoadImage(graph.ImageRoot(id)) 94 if err != nil { 95 return nil, err 96 } 97 if img.ID != id { 98 return nil, fmt.Errorf("Image stored at '%s' has wrong id '%s'", id, img.ID) 99 } 100 img.SetGraph(graph) 101 102 if img.Size < 0 { 103 size, err := graph.driver.DiffSize(img.ID, img.Parent) 104 if err != nil { 105 return nil, fmt.Errorf("unable to calculate size of image id %q: %s", img.ID, err) 106 } 107 108 img.Size = size 109 if err := img.SaveSize(graph.ImageRoot(id)); err != nil { 110 return nil, err 111 } 112 } 113 return img, nil 114 } 115 116 // Create creates a new image and registers it in the graph. 117 func (graph *Graph) Create(layerData archive.ArchiveReader, containerID, containerImage, comment, author string, containerConfig, config *runconfig.Config) (*image.Image, error) { 118 img := &image.Image{ 119 ID: utils.GenerateRandomID(), 120 Comment: comment, 121 Created: time.Now().UTC(), 122 DockerVersion: dockerversion.VERSION, 123 Author: author, 124 Config: config, 125 Architecture: runtime.GOARCH, 126 OS: runtime.GOOS, 127 } 128 129 if containerID != "" { 130 img.Parent = containerImage 131 img.Container = containerID 132 img.ContainerConfig = *containerConfig 133 } 134 135 if err := graph.Register(img, layerData); err != nil { 136 return nil, err 137 } 138 return img, nil 139 } 140 141 // Register imports a pre-existing image into the graph. 142 func (graph *Graph) Register(img *image.Image, layerData archive.ArchiveReader) (err error) { 143 defer func() { 144 // If any error occurs, remove the new dir from the driver. 145 // Don't check for errors since the dir might not have been created. 146 // FIXME: this leaves a possible race condition. 147 if err != nil { 148 graph.driver.Remove(img.ID) 149 } 150 }() 151 if err := utils.ValidateID(img.ID); err != nil { 152 return err 153 } 154 // (This is a convenience to save time. Race conditions are taken care of by os.Rename) 155 if graph.Exists(img.ID) { 156 return fmt.Errorf("Image %s already exists", img.ID) 157 } 158 159 // Ensure that the image root does not exist on the filesystem 160 // when it is not registered in the graph. 161 // This is common when you switch from one graph driver to another 162 if err := os.RemoveAll(graph.ImageRoot(img.ID)); err != nil && !os.IsNotExist(err) { 163 return err 164 } 165 166 // If the driver has this ID but the graph doesn't, remove it from the driver to start fresh. 167 // (the graph is the source of truth). 168 // Ignore errors, since we don't know if the driver correctly returns ErrNotExist. 169 // (FIXME: make that mandatory for drivers). 170 graph.driver.Remove(img.ID) 171 172 tmp, err := graph.Mktemp("") 173 defer os.RemoveAll(tmp) 174 if err != nil { 175 return fmt.Errorf("Mktemp failed: %s", err) 176 } 177 178 // Create root filesystem in the driver 179 if err := graph.driver.Create(img.ID, img.Parent); err != nil { 180 return fmt.Errorf("Driver %s failed to create image rootfs %s: %s", graph.driver, img.ID, err) 181 } 182 // Apply the diff/layer 183 img.SetGraph(graph) 184 if err := image.StoreImage(img, layerData, tmp); err != nil { 185 return err 186 } 187 // Commit 188 if err := os.Rename(tmp, graph.ImageRoot(img.ID)); err != nil { 189 return err 190 } 191 graph.idIndex.Add(img.ID) 192 return nil 193 } 194 195 // TempLayerArchive creates a temporary archive of the given image's filesystem layer. 196 // The archive is stored on disk and will be automatically deleted as soon as has been read. 197 // If output is not nil, a human-readable progress bar will be written to it. 198 // FIXME: does this belong in Graph? How about MktempFile, let the caller use it for archives? 199 func (graph *Graph) TempLayerArchive(id string, compression archive.Compression, sf *utils.StreamFormatter, output io.Writer) (*archive.TempArchive, error) { 200 image, err := graph.Get(id) 201 if err != nil { 202 return nil, err 203 } 204 tmp, err := graph.Mktemp("") 205 if err != nil { 206 return nil, err 207 } 208 a, err := image.TarLayer() 209 if err != nil { 210 return nil, err 211 } 212 progress := utils.ProgressReader(a, 0, output, sf, false, utils.TruncateID(id), "Buffering to disk") 213 defer progress.Close() 214 return archive.NewTempArchive(progress, tmp) 215 } 216 217 // Mktemp creates a temporary sub-directory inside the graph's filesystem. 218 func (graph *Graph) Mktemp(id string) (string, error) { 219 dir := path.Join(graph.Root, "_tmp", utils.GenerateRandomID()) 220 if err := os.MkdirAll(dir, 0700); err != nil { 221 return "", err 222 } 223 return dir, nil 224 } 225 226 // setupInitLayer populates a directory with mountpoints suitable 227 // for bind-mounting dockerinit into the container. The mountpoint is simply an 228 // empty file at /.dockerinit 229 // 230 // This extra layer is used by all containers as the top-most ro layer. It protects 231 // the container from unwanted side-effects on the rw layer. 232 func SetupInitLayer(initLayer string) error { 233 for pth, typ := range map[string]string{ 234 "/dev/pts": "dir", 235 "/dev/shm": "dir", 236 "/proc": "dir", 237 "/sys": "dir", 238 "/.dockerinit": "file", 239 "/.dockerenv": "file", 240 "/etc/resolv.conf": "file", 241 "/etc/hosts": "file", 242 "/etc/hostname": "file", 243 "/dev/console": "file", 244 "/etc/mtab": "/proc/mounts", 245 } { 246 parts := strings.Split(pth, "/") 247 prev := "/" 248 for _, p := range parts[1:] { 249 prev = path.Join(prev, p) 250 syscall.Unlink(path.Join(initLayer, prev)) 251 } 252 253 if _, err := os.Stat(path.Join(initLayer, pth)); err != nil { 254 if os.IsNotExist(err) { 255 if err := os.MkdirAll(path.Join(initLayer, path.Dir(pth)), 0755); err != nil { 256 return err 257 } 258 switch typ { 259 case "dir": 260 if err := os.MkdirAll(path.Join(initLayer, pth), 0755); err != nil { 261 return err 262 } 263 case "file": 264 f, err := os.OpenFile(path.Join(initLayer, pth), os.O_CREATE, 0755) 265 if err != nil { 266 return err 267 } 268 f.Close() 269 default: 270 if err := os.Symlink(typ, path.Join(initLayer, pth)); err != nil { 271 return err 272 } 273 } 274 } else { 275 return err 276 } 277 } 278 } 279 280 // Layer is ready to use, if it wasn't before. 281 return nil 282 } 283 284 // Check if given error is "not empty". 285 // Note: this is the way golang does it internally with os.IsNotExists. 286 func isNotEmpty(err error) bool { 287 switch pe := err.(type) { 288 case nil: 289 return false 290 case *os.PathError: 291 err = pe.Err 292 case *os.LinkError: 293 err = pe.Err 294 } 295 return strings.Contains(err.Error(), " not empty") 296 } 297 298 // Delete atomically removes an image from the graph. 299 func (graph *Graph) Delete(name string) error { 300 id, err := graph.idIndex.Get(name) 301 if err != nil { 302 return err 303 } 304 tmp, err := graph.Mktemp("") 305 graph.idIndex.Delete(id) 306 if err == nil { 307 err = os.Rename(graph.ImageRoot(id), tmp) 308 // On err make tmp point to old dir and cleanup unused tmp dir 309 if err != nil { 310 os.RemoveAll(tmp) 311 tmp = graph.ImageRoot(id) 312 } 313 } else { 314 // On err make tmp point to old dir for cleanup 315 tmp = graph.ImageRoot(id) 316 } 317 // Remove rootfs data from the driver 318 graph.driver.Remove(id) 319 // Remove the trashed image directory 320 return os.RemoveAll(tmp) 321 } 322 323 // Map returns a list of all images in the graph, addressable by ID. 324 func (graph *Graph) Map() (map[string]*image.Image, error) { 325 images := make(map[string]*image.Image) 326 err := graph.walkAll(func(image *image.Image) { 327 images[image.ID] = image 328 }) 329 if err != nil { 330 return nil, err 331 } 332 return images, nil 333 } 334 335 // walkAll iterates over each image in the graph, and passes it to a handler. 336 // The walking order is undetermined. 337 func (graph *Graph) walkAll(handler func(*image.Image)) error { 338 files, err := ioutil.ReadDir(graph.Root) 339 if err != nil { 340 return err 341 } 342 for _, st := range files { 343 if img, err := graph.Get(st.Name()); err != nil { 344 // Skip image 345 continue 346 } else if handler != nil { 347 handler(img) 348 } 349 } 350 return nil 351 } 352 353 // ByParent returns a lookup table of images by their parent. 354 // If an image of id ID has 3 children images, then the value for key ID 355 // will be a list of 3 images. 356 // If an image has no children, it will not have an entry in the table. 357 func (graph *Graph) ByParent() (map[string][]*image.Image, error) { 358 byParent := make(map[string][]*image.Image) 359 err := graph.walkAll(func(img *image.Image) { 360 parent, err := graph.Get(img.Parent) 361 if err != nil { 362 return 363 } 364 if children, exists := byParent[parent.ID]; exists { 365 byParent[parent.ID] = append(children, img) 366 } else { 367 byParent[parent.ID] = []*image.Image{img} 368 } 369 }) 370 return byParent, err 371 } 372 373 // Heads returns all heads in the graph, keyed by id. 374 // A head is an image which is not the parent of another image in the graph. 375 func (graph *Graph) Heads() (map[string]*image.Image, error) { 376 heads := make(map[string]*image.Image) 377 byParent, err := graph.ByParent() 378 if err != nil { 379 return nil, err 380 } 381 err = graph.walkAll(func(image *image.Image) { 382 // If it's not in the byParent lookup table, then 383 // it's not a parent -> so it's a head! 384 if _, exists := byParent[image.ID]; !exists { 385 heads[image.ID] = image 386 } 387 }) 388 return heads, err 389 } 390 391 func (graph *Graph) ImageRoot(id string) string { 392 return path.Join(graph.Root, id) 393 } 394 395 func (graph *Graph) Driver() graphdriver.Driver { 396 return graph.driver 397 }