2637e29e18
This change contains the initial implementation of the LayerService to power layer push and pulls on the storagedriver. The interfaces presented in this package will be used by the http application to drive most features around efficient pulls and resumable pushes. The file storage/layer.go defines the interface interactions. LayerService is the root type and supports methods to access Layer and LayerUpload objects. Pull operations are supported with LayerService.Fetch and push operations are supported with LayerService.Upload and LayerService.Resume. Reads and writes of layers are split between Layer and LayerUpload, respectively. LayerService is implemented internally with the layerStore object, which takes a storagedriver.StorageDriver and a pathMapper instance. LayerUploadState is currently exported and will likely continue to be as the interaction between it and layerUploadStore are better understood. Likely, the layerUploadStore lifecycle and implementation will be deferred to the application. Image pushes pulls will be implemented in a similar manner without the discrete, persistent upload. Much of this change is in place to get something running and working. Caveats of this change include the following: 1. Layer upload state storage is implemented on the local filesystem, separate from the storage driver. This must be replaced with using the proper backend and other state storage. This can be removed when we implement resumable hashing and tarsum calculations to avoid backend roundtrips. 2. Error handling is rather bespoke at this time. The http API implementation should really dictate the error return structure for the future, so we intend to refactor this heavily to support these errors. We'd also like to collect production data to understand how failures happen in the system as a while before moving to a particular edict around error handling. 3. The layerUploadStore, which manages layer upload storage and state is not currently exported. This will likely end up being split, with the file management portion being pointed at the storagedriver and the state storage elsewhere. 4. Access Control provisions are nearly completely missing from this change. There are details around how layerindex lookup works that are related with access controls. As the auth portions of the new API take shape, these provisions will become more clear. Please see TODOs for details and individual recommendations.
45 lines
1.3 KiB
Go
45 lines
1.3 KiB
Go
package storage
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import (
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"github.com/docker/docker-registry/storagedriver"
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)
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// Services provides various services with application-level operations for
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// use across backend storage drivers.
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type Services struct {
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driver storagedriver.StorageDriver
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pathMapper *pathMapper
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layerUploadStore layerUploadStore
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}
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// NewServices creates a new Services object to access docker objects stored
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// in the underlying driver.
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func NewServices(driver storagedriver.StorageDriver) *Services {
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layerUploadStore, err := newTemporaryLocalFSLayerUploadStore()
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if err != nil {
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// TODO(stevvooe): This failure needs to be understood in the context
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// of the lifecycle of the services object, which is uncertain at this
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// point.
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panic("unable to allocate layerUploadStore: " + err.Error())
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}
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return &Services{
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driver: driver,
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pathMapper: &pathMapper{
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// TODO(sday): This should be configurable.
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root: "/docker/registry/",
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version: storagePathVersion,
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},
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layerUploadStore: layerUploadStore,
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}
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}
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// Layers returns an instance of the LayerService. Instantiation is cheap and
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// may be context sensitive in the future. The instance should be used similar
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// to a request local.
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func (ss *Services) Layers() LayerService {
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return &layerStore{driver: ss.driver, pathMapper: ss.pathMapper}
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}
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