212 lines
7.3 KiB
Go
212 lines
7.3 KiB
Go
package distribution
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import (
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"fmt"
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"os"
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"strings"
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"github.com/Sirupsen/logrus"
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"github.com/docker/docker/api"
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"github.com/docker/docker/distribution/metadata"
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"github.com/docker/docker/distribution/xfer"
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"github.com/docker/docker/image"
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"github.com/docker/docker/pkg/progress"
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"github.com/docker/docker/reference"
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"github.com/docker/docker/registry"
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"github.com/docker/engine-api/types"
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"golang.org/x/net/context"
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)
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// ImagePullConfig stores pull configuration.
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type ImagePullConfig struct {
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// MetaHeaders stores HTTP headers with metadata about the image
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// (DockerHeaders with prefix X-Meta- in the request).
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MetaHeaders map[string][]string
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// AuthConfig holds authentication credentials for authenticating with
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// the registry.
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AuthConfig *types.AuthConfig
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// ProgressOutput is the interface for showing the status of the pull
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// operation.
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ProgressOutput progress.Output
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// RegistryService is the registry service to use for TLS configuration
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// and endpoint lookup.
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RegistryService *registry.Service
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// ImageEventLogger notifies events for a given image
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ImageEventLogger func(id, name, action string)
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// MetadataStore is the storage backend for distribution-specific
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// metadata.
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MetadataStore metadata.Store
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// ImageStore manages images.
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ImageStore image.Store
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// ReferenceStore manages tags.
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ReferenceStore reference.Store
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// DownloadManager manages concurrent pulls.
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DownloadManager *xfer.LayerDownloadManager
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}
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// Puller is an interface that abstracts pulling for different API versions.
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type Puller interface {
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// Pull tries to pull the image referenced by `tag`
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// Pull returns an error if any, as well as a boolean that determines whether to retry Pull on the next configured endpoint.
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//
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Pull(ctx context.Context, ref reference.Named) error
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}
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// newPuller returns a Puller interface that will pull from either a v1 or v2
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// registry. The endpoint argument contains a Version field that determines
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// whether a v1 or v2 puller will be created. The other parameters are passed
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// through to the underlying puller implementation for use during the actual
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// pull operation.
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func newPuller(endpoint registry.APIEndpoint, repoInfo *registry.RepositoryInfo, imagePullConfig *ImagePullConfig) (Puller, error) {
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switch endpoint.Version {
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case registry.APIVersion2:
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return &v2Puller{
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V2MetadataService: metadata.NewV2MetadataService(imagePullConfig.MetadataStore),
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endpoint: endpoint,
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config: imagePullConfig,
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repoInfo: repoInfo,
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}, nil
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case registry.APIVersion1:
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return &v1Puller{
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v1IDService: metadata.NewV1IDService(imagePullConfig.MetadataStore),
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endpoint: endpoint,
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config: imagePullConfig,
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repoInfo: repoInfo,
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}, nil
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}
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return nil, fmt.Errorf("unknown version %d for registry %s", endpoint.Version, endpoint.URL)
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}
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// Pull initiates a pull operation. image is the repository name to pull, and
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// tag may be either empty, or indicate a specific tag to pull.
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func Pull(ctx context.Context, ref reference.Named, imagePullConfig *ImagePullConfig) error {
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// Resolve the Repository name from fqn to RepositoryInfo
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repoInfo, err := imagePullConfig.RegistryService.ResolveRepository(ref)
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if err != nil {
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return err
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}
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// makes sure name is not empty or `scratch`
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if err := validateRepoName(repoInfo.Name()); err != nil {
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return err
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}
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endpoints, err := imagePullConfig.RegistryService.LookupPullEndpoints(repoInfo)
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if err != nil {
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return err
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}
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var (
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// use a slice to append the error strings and return a joined string to caller
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errors []string
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// discardNoSupportErrors is used to track whether an endpoint encountered an error of type registry.ErrNoSupport
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// By default it is false, which means that if a ErrNoSupport error is encountered, it will be saved in errors.
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// As soon as another kind of error is encountered, discardNoSupportErrors is set to true, avoiding the saving of
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// any subsequent ErrNoSupport errors in errors.
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// It's needed for pull-by-digest on v1 endpoints: if there are only v1 endpoints configured, the error should be
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// returned and displayed, but if there was a v2 endpoint which supports pull-by-digest, then the last relevant
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// error is the ones from v2 endpoints not v1.
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discardNoSupportErrors bool
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// confirmedV2 is set to true if a pull attempt managed to
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// confirm that it was talking to a v2 registry. This will
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// prevent fallback to the v1 protocol.
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confirmedV2 bool
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)
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for _, endpoint := range endpoints {
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if confirmedV2 && endpoint.Version == registry.APIVersion1 {
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logrus.Debugf("Skipping v1 endpoint %s because v2 registry was detected", endpoint.URL)
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continue
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}
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logrus.Debugf("Trying to pull %s from %s %s", repoInfo.Name(), endpoint.URL, endpoint.Version)
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puller, err := newPuller(endpoint, repoInfo, imagePullConfig)
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if err != nil {
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errors = append(errors, err.Error())
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continue
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}
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if err := puller.Pull(ctx, ref); err != nil {
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// Was this pull cancelled? If so, don't try to fall
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// back.
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fallback := false
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select {
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case <-ctx.Done():
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default:
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if fallbackErr, ok := err.(fallbackError); ok {
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fallback = true
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confirmedV2 = confirmedV2 || fallbackErr.confirmedV2
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err = fallbackErr.err
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}
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}
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if fallback {
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if _, ok := err.(registry.ErrNoSupport); !ok {
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// Because we found an error that's not ErrNoSupport, discard all subsequent ErrNoSupport errors.
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discardNoSupportErrors = true
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// append subsequent errors
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errors = append(errors, err.Error())
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} else if !discardNoSupportErrors {
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// Save the ErrNoSupport error, because it's either the first error or all encountered errors
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// were also ErrNoSupport errors.
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// append subsequent errors
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errors = append(errors, err.Error())
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}
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continue
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}
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errors = append(errors, err.Error())
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logrus.Debugf("Not continuing with error: %v", fmt.Errorf(strings.Join(errors, "\n")))
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if len(errors) > 0 {
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return fmt.Errorf(strings.Join(errors, "\n"))
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}
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}
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imagePullConfig.ImageEventLogger(ref.String(), repoInfo.Name(), "pull")
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return nil
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}
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if len(errors) == 0 {
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return fmt.Errorf("no endpoints found for %s", ref.String())
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}
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if len(errors) > 0 {
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return fmt.Errorf(strings.Join(errors, "\n"))
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}
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return nil
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}
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// writeStatus writes a status message to out. If layersDownloaded is true, the
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// status message indicates that a newer image was downloaded. Otherwise, it
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// indicates that the image is up to date. requestedTag is the tag the message
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// will refer to.
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func writeStatus(requestedTag string, out progress.Output, layersDownloaded bool) {
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if layersDownloaded {
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progress.Message(out, "", "Status: Downloaded newer image for "+requestedTag)
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} else {
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progress.Message(out, "", "Status: Image is up to date for "+requestedTag)
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}
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}
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// validateRepoName validates the name of a repository.
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func validateRepoName(name string) error {
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if name == "" {
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return fmt.Errorf("Repository name can't be empty")
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}
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if name == api.NoBaseImageSpecifier {
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return fmt.Errorf("'%s' is a reserved name", api.NoBaseImageSpecifier)
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}
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return nil
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}
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// tmpFileClose creates a closer function for a temporary file that closes the file
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// and also deletes it.
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func tmpFileCloser(tmpFile *os.File) func() error {
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return func() error {
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tmpFile.Close()
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if err := os.RemoveAll(tmpFile.Name()); err != nil {
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logrus.Errorf("Failed to remove temp file: %s", tmpFile.Name())
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}
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return nil
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}
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}
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