package distribution import ( "fmt" "io" "strings" "github.com/Sirupsen/logrus" "github.com/docker/distribution/reference" "github.com/docker/docker/cliconfig" "github.com/docker/docker/daemon/events" "github.com/docker/docker/distribution/metadata" "github.com/docker/docker/image" "github.com/docker/docker/layer" "github.com/docker/docker/pkg/streamformatter" "github.com/docker/docker/registry" "github.com/docker/docker/tag" ) // ImagePullConfig stores pull configuration. type ImagePullConfig struct { // MetaHeaders stores HTTP headers with metadata about the image // (DockerHeaders with prefix X-Meta- in the request). MetaHeaders map[string][]string // AuthConfig holds authentication credentials for authenticating with // the registry. AuthConfig *cliconfig.AuthConfig // OutStream is the output writer for showing the status of the pull // operation. OutStream io.Writer // RegistryService is the registry service to use for TLS configuration // and endpoint lookup. RegistryService *registry.Service // EventsService is the events service to use for logging. EventsService *events.Events // MetadataStore is the storage backend for distribution-specific // metadata. MetadataStore metadata.Store // LayerStore manages layers. LayerStore layer.Store // ImageStore manages images. ImageStore image.Store // TagStore manages tags. TagStore tag.Store // Pool manages concurrent pulls. Pool *Pool } // Puller is an interface that abstracts pulling for different API versions. type Puller interface { // Pull tries to pull the image referenced by `tag` // Pull returns an error if any, as well as a boolean that determines whether to retry Pull on the next configured endpoint. // Pull(ref reference.Named) (fallback bool, err error) } // newPuller returns a Puller interface that will pull from either a v1 or v2 // registry. The endpoint argument contains a Version field that determines // whether a v1 or v2 puller will be created. The other parameters are passed // through to the underlying puller implementation for use during the actual // pull operation. func newPuller(endpoint registry.APIEndpoint, repoInfo *registry.RepositoryInfo, imagePullConfig *ImagePullConfig, sf *streamformatter.StreamFormatter) (Puller, error) { switch endpoint.Version { case registry.APIVersion2: return &v2Puller{ blobSumService: metadata.NewBlobSumService(imagePullConfig.MetadataStore), endpoint: endpoint, config: imagePullConfig, sf: sf, repoInfo: repoInfo, }, nil case registry.APIVersion1: return &v1Puller{ v1IDService: metadata.NewV1IDService(imagePullConfig.MetadataStore), endpoint: endpoint, config: imagePullConfig, sf: sf, repoInfo: repoInfo, }, nil } return nil, fmt.Errorf("unknown version %d for registry %s", endpoint.Version, endpoint.URL) } // Pull initiates a pull operation. image is the repository name to pull, and // tag may be either empty, or indicate a specific tag to pull. func Pull(ref reference.Named, imagePullConfig *ImagePullConfig) error { var sf = streamformatter.NewJSONStreamFormatter() // Resolve the Repository name from fqn to RepositoryInfo repoInfo, err := imagePullConfig.RegistryService.ResolveRepository(ref) if err != nil { return err } // makes sure name is not empty or `scratch` if err := validateRepoName(repoInfo.LocalName.Name()); err != nil { return err } endpoints, err := imagePullConfig.RegistryService.LookupPullEndpoints(repoInfo.CanonicalName) if err != nil { return err } logName := registry.NormalizeLocalReference(ref) var ( // use a slice to append the error strings and return a joined string to caller errors []string // discardNoSupportErrors is used to track whether an endpoint encountered an error of type registry.ErrNoSupport // By default it is false, which means that if a ErrNoSupport error is encountered, it will be saved in errors. // As soon as another kind of error is encountered, discardNoSupportErrors is set to true, avoiding the saving of // any subsequent ErrNoSupport errors in errors. // It's needed for pull-by-digest on v1 endpoints: if there are only v1 endpoints configured, the error should be // returned and displayed, but if there was a v2 endpoint which supports pull-by-digest, then the last relevant // error is the ones from v2 endpoints not v1. discardNoSupportErrors bool ) for _, endpoint := range endpoints { logrus.Debugf("Trying to pull %s from %s %s", repoInfo.LocalName, endpoint.URL, endpoint.Version) puller, err := newPuller(endpoint, repoInfo, imagePullConfig, sf) if err != nil { errors = append(errors, err.Error()) continue } if fallback, err := puller.Pull(ref); err != nil { if fallback { if _, ok := err.(registry.ErrNoSupport); !ok { // Because we found an error that's not ErrNoSupport, discard all subsequent ErrNoSupport errors. discardNoSupportErrors = true // append subsequent errors errors = append(errors, err.Error()) } else if !discardNoSupportErrors { // Save the ErrNoSupport error, because it's either the first error or all encountered errors // were also ErrNoSupport errors. // append subsequent errors errors = append(errors, err.Error()) } continue } errors = append(errors, err.Error()) logrus.Debugf("Not continuing with error: %v", fmt.Errorf(strings.Join(errors, "\n"))) if len(errors) > 0 { return fmt.Errorf(strings.Join(errors, "\n")) } } imagePullConfig.EventsService.Log("pull", logName.String(), "") return nil } if len(errors) == 0 { return fmt.Errorf("no endpoints found for %s", ref.String()) } if len(errors) > 0 { return fmt.Errorf(strings.Join(errors, "\n")) } return nil } // writeStatus writes a status message to out. If layersDownloaded is true, the // status message indicates that a newer image was downloaded. Otherwise, it // indicates that the image is up to date. requestedTag is the tag the message // will refer to. func writeStatus(requestedTag string, out io.Writer, sf *streamformatter.StreamFormatter, layersDownloaded bool) { if layersDownloaded { out.Write(sf.FormatStatus("", "Status: Downloaded newer image for %s", requestedTag)) } else { out.Write(sf.FormatStatus("", "Status: Image is up to date for %s", requestedTag)) } } // validateRepoName validates the name of a repository. func validateRepoName(name string) error { if name == "" { return fmt.Errorf("Repository name can't be empty") } if name == "scratch" { return fmt.Errorf("'scratch' is a reserved name") } return nil }