85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
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package storage
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import (
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"net/http"
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"github.com/docker/distribution/digest"
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"github.com/docker/distribution/storagedriver"
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)
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// delegateLayerHandler provides a simple implementation of layerHandler that
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// simply issues HTTP Temporary Redirects to the URL provided by the
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// storagedriver for a given Layer.
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type delegateLayerHandler struct {
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storageDriver storagedriver.StorageDriver
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pathMapper *pathMapper
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}
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var _ LayerHandler = &delegateLayerHandler{}
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func newDelegateLayerHandler(storageDriver storagedriver.StorageDriver, options map[string]interface{}) (LayerHandler, error) {
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return &delegateLayerHandler{storageDriver: storageDriver, pathMapper: defaultPathMapper}, nil
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}
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// Resolve returns an http.Handler which can serve the contents of the given
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// Layer, or an error if not supported by the storagedriver.
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func (lh *delegateLayerHandler) Resolve(layer Layer) (http.Handler, error) {
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layerURL, err := lh.urlFor(layer)
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if err != nil {
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return nil, err
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}
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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http.Redirect(w, r, layerURL, http.StatusTemporaryRedirect)
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}), nil
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}
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// urlFor returns a download URL for the given layer, or the empty string if
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// unsupported.
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func (lh *delegateLayerHandler) urlFor(layer Layer) (string, error) {
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blobPath, err := lh.resolveBlobPath(layer.Name(), layer.Digest())
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if err != nil {
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return "", err
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}
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layerURL, err := lh.storageDriver.URLFor(blobPath)
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if err != nil {
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return "", err
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}
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return layerURL, nil
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}
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// resolveBlobPath looks up the blob location in the repositories from a
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// layer/blob link file, returning blob path or an error on failure.
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func (lh *delegateLayerHandler) resolveBlobPath(name string, dgst digest.Digest) (string, error) {
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pathSpec := layerLinkPathSpec{name: name, digest: dgst}
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layerLinkPath, err := lh.pathMapper.path(pathSpec)
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if err != nil {
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return "", err
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}
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layerLinkContent, err := lh.storageDriver.GetContent(layerLinkPath)
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if err != nil {
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return "", err
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}
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// NOTE(stevvooe): The content of the layer link should match the digest.
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// This layer of indirection is for name-based content protection.
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linked, err := digest.ParseDigest(string(layerLinkContent))
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if err != nil {
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return "", err
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}
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bp := blobPathSpec{digest: linked}
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return lh.pathMapper.path(bp)
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}
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// init registers the delegate layerHandler backend.
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func init() {
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RegisterLayerHandler("delegate", LayerHandlerInitFunc(newDelegateLayerHandler))
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}
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