95 lines
2.8 KiB
Go
95 lines
2.8 KiB
Go
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package storage
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import (
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"fmt"
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"net/http"
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"time"
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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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duration time.Duration
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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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duration := 20 * time.Minute
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d, ok := options["duration"]
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if ok {
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switch d := d.(type) {
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case time.Duration:
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duration = d
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case string:
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dur, err := time.ParseDuration(d)
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if err != nil {
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return nil, fmt.Errorf("Invalid duration: %s", err)
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}
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duration = dur
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}
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}
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return &delegateLayerHandler{storageDriver: storageDriver, pathMapper: defaultPathMapper, duration: duration}, 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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// TODO(bbland): This is just a sanity check to ensure that the
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// storagedriver supports url generation. It would be nice if we didn't have
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// to do this twice for non-GET requests.
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layerURL, err := lh.urlFor(layer, map[string]interface{}{"method": "GET"})
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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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if r.Method != "GET" {
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layerURL, err = lh.urlFor(layer, map[string]interface{}{"method": r.Method})
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if err != nil {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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return
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}
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}
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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, options map[string]interface{}) (string, error) {
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// Crack open the layer to get at the layerStore
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layerRd, ok := layer.(*layerReader)
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if !ok {
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// TODO(stevvooe): We probably want to find a better way to get at the
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// underlying filesystem path for a given layer. Perhaps, the layer
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// handler should have its own layer store but right now, it is not
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// request scoped.
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return "", fmt.Errorf("unsupported layer type: cannot resolve blob path: %v", layer)
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}
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if options == nil {
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options = make(map[string]interface{})
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}
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options["expiry"] = time.Now().Add(lh.duration)
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layerURL, err := lh.storageDriver.URLFor(layerRd.path, options)
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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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// 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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