0e1b1cc04e
These methods rely on an ObjectStore interface, which is meant to approximate the storage behavior of the docker engine. This is very much subject to change.
93 lines
2.2 KiB
Go
93 lines
2.2 KiB
Go
package client
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import (
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"fmt"
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"io"
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log "github.com/Sirupsen/logrus"
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)
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// Pull implements a client pull workflow for the image defined by the given
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// name and tag pair, using the given ObjectStore for local manifest and layer
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// storage
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func Pull(c Client, objectStore ObjectStore, name, tag string) error {
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manifest, err := c.GetImageManifest(name, tag)
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if err != nil {
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return err
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}
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log.WithField("manifest", manifest).Info("Pulled manifest")
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if len(manifest.FSLayers) != len(manifest.History) {
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return fmt.Errorf("Length of history not equal to number of layers")
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}
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if len(manifest.FSLayers) == 0 {
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return fmt.Errorf("Image has no layers")
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}
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for _, fsLayer := range manifest.FSLayers {
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layer, err := objectStore.Layer(fsLayer.BlobSum)
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if err != nil {
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log.WithFields(log.Fields{
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"error": err,
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"layer": fsLayer,
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}).Warn("Unable to write local layer")
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return err
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}
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writer, err := layer.Writer()
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if err == ErrLayerAlreadyExists {
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log.WithField("layer", fsLayer).Info("Layer already exists")
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continue
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}
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if err == ErrLayerLocked {
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log.WithField("layer", fsLayer).Info("Layer download in progress, waiting")
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layer.Wait()
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continue
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}
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if err != nil {
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log.WithFields(log.Fields{
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"error": err,
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"layer": fsLayer,
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}).Warn("Unable to write local layer")
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return err
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}
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defer writer.Close()
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layerReader, length, err := c.GetImageLayer(name, fsLayer.BlobSum, 0)
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if err != nil {
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log.WithFields(log.Fields{
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"error": err,
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"layer": fsLayer,
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}).Warn("Unable to download layer")
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return err
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}
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defer layerReader.Close()
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copied, err := io.Copy(writer, layerReader)
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if err != nil {
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log.WithFields(log.Fields{
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"error": err,
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"layer": fsLayer,
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}).Warn("Unable to download layer")
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return err
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}
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if copied != int64(length) {
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log.WithFields(log.Fields{
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"expected": length,
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"written": copied,
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"layer": fsLayer,
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}).Warn("Wrote incorrect number of bytes for layer")
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}
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}
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err = objectStore.WriteManifest(name, tag, manifest)
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if err != nil {
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log.WithFields(log.Fields{
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"error": err,
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"manifest": manifest,
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}).Warn("Unable to write image manifest")
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return err
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}
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return nil
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}
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