regclient

README

regclient

Client interface for the registry API. This includes regctl for a command line interface to manage registries.

regclient Features

• Provides a client interface to interacting with registries.
• Images may be inspected without pulling the layers, allowing quick access to the image manifest and configuration.
• Tags may be listed for a repository.
• Repositories may be listed from a registry (if supported).
• Copying an image only pulls layers when needed, allowing images to be quickly retagged or promoted across repositories.
• Multi-platform images are supported, allowing all platforms to be copied between registries.
• Digest tags used by projects like sigstore/cosign are supported, allowing signature, attestation, and SBOM metadata to be copied with the image.
• OCI subject/referrers is supported for the standardized replacement of the "digest tags".
• Digests may be queried for a tag without pulling the manifest.
• Rate limits may be queried from the registry without pulling an image (useful for Docker Hub).
• Images may be imported and exported to both OCI and Docker formatted tar files.
• OCI Layout is supported for copying images to and from a local directory.
• Delete APIs have been provided for tags, manifests, and blobs (the tag deletion will only delete a single tag even if multiple tags point to the same digest).
• Registry logins are imported from docker when available
• Self signed, insecure, and http-only registries are all supported.
• Requests will retry and fall back to chunked uploads when network issues are encountered.

regctl Features

regctl is a CLI interface to the regclient library. In addition to the features listed for regclient, regctl adds the following abilities:

• Formatting output with templates.
• Push and pull arbitrary artifacts.

regsync features

regsync is an image mirroring tool. It will copy images between two locations with the following additional features:

• Uses a yaml configuration.
• The regclient copy is used to only pull needed layers, supporting multi-platform, and additional metadata.
• Can use user's docker configuration for registry credentials.
• Ability to run on a cron schedule, one time synchronization, or only check for stale images.
• Ability to backup previous target image before overwriting.
• Ability to postpone mirror step when rate limit is below a threshold.
• Ability to mirror multiple images concurrently.

regbot features

regbot is a scripting tool on top of the regclient API with the following features:

• Runs user provided scripts based on a yaml configuration.
• Scripts are written in Lua and executed directly in Go.
• Can run on a cron schedule or a one time execution.
• Dry-run option can be used for testing.
• Built-in functions include:
  • Repository list
  • Tag list
  • Image manifest (either head or get, and optional resolving multi-platform reference)
  • Image config (this includes the creation time, labels, and other details shown in a docker image inspect)
  • Image rate limit and a wait function to delay the script when rate limit remaining is below a threshold
  • Image copy
  • Manifest delete
  • Tag delete

Development Status

This project is in active development. Various Go APIs may change, but efforts will be made to provide aliases and stubs for any removed API.

Installing

See the installation options.

Usage

See the project documentation.

Contributors

Documentation

Overview

Package regclient is used to access OCI registries.

Index

• Constants
• type BlobOpts
  • func BlobWithCallback(...) BlobOpts
• type ImageOpts
  • func ImageWithCallback(...) ImageOpts
  • func ImageWithCheckBaseDigest(d string) ImageOpts
  • func ImageWithCheckBaseRef(r string) ImageOpts
  • func ImageWithCheckSkipConfig() ImageOpts
  • func ImageWithChild() ImageOpts
  • func ImageWithDigestTags() ImageOpts
  • func ImageWithExportCompress() ImageOpts
  • func ImageWithExportRef(r ref.Ref) ImageOpts
  • func ImageWithFastCheck() ImageOpts
  • func ImageWithForceRecursive() ImageOpts
  • func ImageWithImportName(name string) ImageOpts
  • func ImageWithIncludeExternal() ImageOpts
  • func ImageWithPlatform(p string) ImageOpts
  • func ImageWithPlatforms(p []string) ImageOpts
  • func ImageWithReferrerSrc(src ref.Ref) ImageOpts
  • func ImageWithReferrerTgt(tgt ref.Ref) ImageOpts
  • func ImageWithReferrers(rOpts ...scheme.ReferrerOpts) ImageOpts
• type ManifestOpts
  • func WithManifest(m manifest.Manifest) ManifestOpts
  • func WithManifestCheckReferrers() ManifestOpts
  • func WithManifestChild() ManifestOpts
  • func WithManifestDesc(d descriptor.Descriptor) ManifestOpts
  • func WithManifestPlatform(p platform.Platform) ManifestOpts
  • func WithManifestRequireDigest() ManifestOpts
• type Opt
  • func WithBlobLimit(limit int64) Opt
  • func WithBlobSize(chunk, max int64) Opt
  • func WithCertDir(path ...string) Opt
  • func WithConfigHost(configHost ...config.Host) Opt
  • func WithConfigHostDefault(configHost config.Host) Opt
  • func WithConfigHosts(configHosts []config.Host) Opt
  • func WithDockerCerts() Opt
  • func WithDockerCreds() Opt
  • func WithDockerCredsFile(fname string) Opt
  • func WithLog(log *logrus.Logger) Opt
  • func WithRegOpts(opts ...reg.Opts) Opt
  • func WithRetryDelay(delayInit, delayMax time.Duration) Opt
  • func WithRetryLimit(retryLimit int) Opt
  • func WithSlog(slog *slog.Logger) Opt
  • func WithUserAgent(ua string) Opt
• type RegClient
  • func New(opts ...Opt) *RegClient
  • func (rc *RegClient) BlobCopy(ctx context.Context, refSrc ref.Ref, refTgt ref.Ref, d descriptor.Descriptor, ...) error
  • func (rc *RegClient) BlobDelete(ctx context.Context, r ref.Ref, d descriptor.Descriptor) error
  • func (rc *RegClient) BlobGet(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.Reader, error)
  • func (rc *RegClient) BlobGetOCIConfig(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.OCIConfig, error)
  • func (rc *RegClient) BlobHead(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.Reader, error)
  • func (rc *RegClient) BlobMount(ctx context.Context, refSrc ref.Ref, refTgt ref.Ref, d descriptor.Descriptor) error
  • func (rc *RegClient) BlobPut(ctx context.Context, r ref.Ref, d descriptor.Descriptor, rdr io.Reader) (descriptor.Descriptor, error)
  • func (rc *RegClient) Close(ctx context.Context, r ref.Ref) error
  • func (rc *RegClient) ImageCheckBase(ctx context.Context, r ref.Ref, opts ...ImageOpts) error
  • func (rc *RegClient) ImageConfig(ctx context.Context, r ref.Ref, opts ...ImageOpts) (*blob.BOCIConfig, error)
  • func (rc *RegClient) ImageCopy(ctx context.Context, refSrc ref.Ref, refTgt ref.Ref, opts ...ImageOpts) error
  • func (rc *RegClient) ImageExport(ctx context.Context, r ref.Ref, outStream io.Writer, opts ...ImageOpts) error
  • func (rc *RegClient) ImageImport(ctx context.Context, r ref.Ref, rs io.ReadSeeker, opts ...ImageOpts) error
  • func (rc *RegClient) ManifestDelete(ctx context.Context, r ref.Ref, opts ...ManifestOpts) error
  • func (rc *RegClient) ManifestGet(ctx context.Context, r ref.Ref, opts ...ManifestOpts) (manifest.Manifest, error)
  • func (rc *RegClient) ManifestHead(ctx context.Context, r ref.Ref, opts ...ManifestOpts) (manifest.Manifest, error)
  • func (rc *RegClient) ManifestPut(ctx context.Context, r ref.Ref, m manifest.Manifest, opts ...ManifestOpts) error
  • func (rc *RegClient) Ping(ctx context.Context, r ref.Ref) (ping.Result, error)
  • func (rc *RegClient) ReferrerList(ctx context.Context, rSubject ref.Ref, opts ...scheme.ReferrerOpts) (referrer.ReferrerList, error)
  • func (rc *RegClient) RepoList(ctx context.Context, hostname string, opts ...scheme.RepoOpts) (*repo.RepoList, error)
  • func (rc *RegClient) TagDelete(ctx context.Context, r ref.Ref) error
  • func (rc *RegClient) TagList(ctx context.Context, r ref.Ref, opts ...scheme.TagOpts) (*tag.List, error)

Examples

• New

Constants

const (
	// DefaultUserAgent sets the header on http requests.
	DefaultUserAgent = "regclient/regclient"
	// DockerCertDir default location for docker certs.
	DockerCertDir = "/etc/docker/certs.d"
	// DockerRegistry is the well known name of Docker Hub, "docker.io".
	DockerRegistry = config.DockerRegistry
	// DockerRegistryAuth is the name of Docker Hub seen in docker's config.json.
	DockerRegistryAuth = config.DockerRegistryAuth
	// DockerRegistryDNS is the actual registry DNS name for Docker Hub.
	DockerRegistryDNS = config.DockerRegistryDNS
)

Types

type BlobOpts

type BlobOpts func(*blobOpt)

BlobOpts define options for the Image* commands.

func BlobWithCallback

func BlobWithCallback(callback func(kind types.CallbackKind, instance string, state types.CallbackState, cur, total int64)) BlobOpts

BlobWithCallback provides progress data to a callback function.

type ImageOpts

type ImageOpts func(*imageOpt)

ImageOpts define options for the Image* commands.

func ImageWithCallback

func ImageWithCallback(callback func(kind types.CallbackKind, instance string, state types.CallbackState, cur, total int64)) ImageOpts

ImageWithCallback provides progress data to a callback function.

func ImageWithCheckBaseDigest

func ImageWithCheckBaseDigest(d string) ImageOpts

ImageWithCheckBaseDigest provides a base digest to compare in ImageCheckBase.

func ImageWithCheckBaseRef

func ImageWithCheckBaseRef(r string) ImageOpts

ImageWithCheckBaseRef provides a base reference to compare in ImageCheckBase.

func ImageWithCheckSkipConfig

func ImageWithCheckSkipConfig() ImageOpts

ImageWithCheckSkipConfig skips the configuration check in ImageCheckBase.

func ImageWithChild

func ImageWithChild() ImageOpts

ImageWithChild attempts to copy every manifest and blob even if parent manifests already exist in ImageCopy.

func ImageWithDigestTags

func ImageWithDigestTags() ImageOpts

ImageWithDigestTags looks for "sha-<digest>.*" tags in the repo to copy with any manifest in ImageCopy. These are used by some artifact systems like sigstore/cosign.

func ImageWithExportCompress

func ImageWithExportCompress() ImageOpts

ImageWithExportCompress adds gzip compression to tar export output in ImageExport.

func ImageWithExportRef

func ImageWithExportRef(r ref.Ref) ImageOpts

ImageWithExportRef overrides the image name embedded in the export file in ImageExport.

func ImageWithFastCheck

func ImageWithFastCheck() ImageOpts

ImageWithFastCheck skips check for referrers when manifest has already been copied in ImageCopy.

func ImageWithForceRecursive

func ImageWithForceRecursive() ImageOpts

ImageWithForceRecursive attempts to copy every manifest and blob even if parent manifests already exist in ImageCopy.

func ImageWithImportName

func ImageWithImportName(name string) ImageOpts

ImageWithImportName selects the name of the image to import when multiple images are included in ImageImport.

func ImageWithIncludeExternal

func ImageWithIncludeExternal() ImageOpts

ImageWithIncludeExternal attempts to copy every manifest and blob even if parent manifests already exist in ImageCopy.

func ImageWithPlatform

func ImageWithPlatform(p string) ImageOpts

ImageWithPlatform requests specific platforms from a manifest list in ImageCheckBase.

func ImageWithPlatforms

func ImageWithPlatforms(p []string) ImageOpts

ImageWithPlatforms only copies specific platforms from a manifest list in ImageCopy. This will result in a failure on many registries that validate manifests. Use the empty string to indicate images without a platform definition should be copied.

func ImageWithReferrerSrc

func ImageWithReferrerSrc(src ref.Ref) ImageOpts

ImageWithReferrerSrc specifies an alternate repository to pull referrers from.

func ImageWithReferrerTgt

func ImageWithReferrerTgt(tgt ref.Ref) ImageOpts

ImageWithReferrerTgt specifies an alternate repository to pull referrers from.

func ImageWithReferrers

func ImageWithReferrers(rOpts ...scheme.ReferrerOpts) ImageOpts

ImageWithReferrers recursively recursively includes referrer images in ImageCopy.

type ManifestOpts

type ManifestOpts func(*manifestOpt)

ManifestOpts define options for the Manifest* commands.

func WithManifest

func WithManifest(m manifest.Manifest) ManifestOpts

WithManifest passes a manifest to ManifestDelete.

func WithManifestCheckReferrers

func WithManifestCheckReferrers() ManifestOpts

WithManifestCheckReferrers checks for referrers field on ManifestDelete. This will update the client managed referrer listing.

func WithManifestChild

func WithManifestChild() ManifestOpts

WithManifestChild for ManifestPut indicates the manifest is not the top level manifest being copied. This is used by the ocidir scheme to determine what entries to include in the index.json.

func WithManifestDesc

func WithManifestDesc(d descriptor.Descriptor) ManifestOpts

WithManifestDesc includes the descriptor for ManifestGet. This is used to automatically extract a Data field if available.

func WithManifestPlatform

func WithManifestPlatform(p platform.Platform) ManifestOpts

WithManifestPlatform resolves the platform specific manifest on Get and Head requests. This causes an additional GET query to a registry when an Index or Manifest List is encountered. This option is ignored if the retrieved manifest is not an Index or Manifest List.

func WithManifestRequireDigest

func WithManifestRequireDigest() ManifestOpts

WithManifestRequireDigest falls back from a HEAD to a GET request when digest headers aren't received.

type Opt

type Opt func(*RegClient)

Opt functions are used by New to create a *RegClient.

func WithBlobLimit

func WithBlobLimit(limit int64) Opt

WithBlobLimit sets the max size for chunked blob uploads which get stored in memory.

Deprecated: replace with WithRegOpts(reg.WithBlobLimit(limit)), see WithRegOpts and reg.WithBlobLimit.

func WithBlobSize

func WithBlobSize(chunk, max int64) Opt

WithBlobSize overrides default blob sizes.

Deprecated: replace with WithRegOpts(reg.WithBlobSize(chunk, max)), see WithRegOpts and reg.WithBlobSize.

func WithCertDir

func WithCertDir(path ...string) Opt

WithCertDir adds a path of certificates to trust similar to Docker's /etc/docker/certs.d.

Deprecated: replace with WithRegOpts(reg.WithCertDirs(path)), see WithRegOpts and reg.WithCertDirs.

func WithConfigHost

func WithConfigHost(configHost ...config.Host) Opt

WithConfigHost adds a list of config host settings.

func WithConfigHostDefault

func WithConfigHostDefault(configHost config.Host) Opt

WithConfigHostDefault adds default settings for new hosts.

func WithConfigHosts

func WithConfigHosts(configHosts []config.Host) Opt

WithConfigHosts adds a list of config host settings.

Deprecated: replace with WithConfigHost.

func WithDockerCerts

func WithDockerCerts() Opt

WithDockerCerts adds certificates trusted by docker in /etc/docker/certs.d.

func WithDockerCreds

func WithDockerCreds() Opt

WithDockerCreds adds configuration from users docker config with registry logins. This changes the default value from the config file, and should be added after the config file is loaded.

func WithDockerCredsFile

func WithDockerCredsFile(fname string) Opt

WithDockerCredsFile adds configuration from a named docker config file with registry logins. This changes the default value from the config file, and should be added after the config file is loaded.

func WithLog

func WithLog(log *logrus.Logger) Opt

WithLog configuring logging with a logrus Logger. Note that regclient has switched to log/slog for logging and my eventually deprecate logrus support.

func WithRegOpts

func WithRegOpts(opts ...reg.Opts) Opt

WithRegOpts passes through opts to the reg scheme.

func WithRetryDelay

func WithRetryDelay(delayInit, delayMax time.Duration) Opt

WithRetryDelay specifies the time permitted for retry delays.

Deprecated: replace with WithRegOpts(reg.WithDelay(delayInit, delayMax)), see WithRegOpts and reg.WithDelay.

func WithRetryLimit

func WithRetryLimit(retryLimit int) Opt

WithRetryLimit specifies the number of retries for non-fatal errors.

Deprecated: replace with WithRegOpts(reg.WithRetryLimit(retryLimit)), see WithRegOpts and reg.WithRetryLimit.

func WithSlog

func WithSlog(slog *slog.Logger) Opt

WithSlog configures the slog Logger.

func WithUserAgent

func WithUserAgent(ua string) Opt

WithUserAgent specifies the User-Agent http header.

type RegClient

type RegClient struct {
	// contains filtered or unexported fields
}

RegClient is used to access OCI distribution-spec registries.

func New

func New(opts ...Opt) *RegClient

New returns a registry client.

Example

package main

import (
	"context"
	"fmt"

	"github.com/regclient/regclient"
	"github.com/regclient/regclient/config"
	"github.com/regclient/regclient/types/ref"
)

func main() {
	ctx := context.Background()
	// use config.Host to provide registry logins, TLS, and other registry settings
	exHostLocal := config.Host{
		Name: "registry.example.org:5000",
		TLS:  config.TLSDisabled,
		User: "exUser",
		Pass: "exPass",
	}
	exHostDH := config.Host{
		Name: "docker.io",
		User: "dhUser",
		Pass: "dhPass",
	}
	// define a regclient with desired options
	rc := regclient.New(
		regclient.WithConfigHosts([]config.Host{exHostLocal, exHostDH}),
		regclient.WithDockerCerts(),
		regclient.WithDockerCreds(),
		regclient.WithUserAgent("regclient/example"),
	)
	// create a reference for an image
	r, err := ref.New("ghcr.io/regclient/regctl:latest")
	if err != nil {
		fmt.Printf("failed to create ref: %v\n", err)
		return
	}
	defer rc.Close(ctx, r)
	// get a manifest (or call other regclient methods)
	m, err := rc.ManifestGet(ctx, r)
	if err != nil {
		fmt.Printf("failed to get manifest: %v\n", err)
		return
	}
	fmt.Println(m.GetDescriptor().MediaType)
}

Output:

application/vnd.oci.image.index.v1+json

func (*RegClient) BlobCopy

func (rc *RegClient) BlobCopy(ctx context.Context, refSrc ref.Ref, refTgt ref.Ref, d descriptor.Descriptor, opts ...BlobOpts) error

BlobCopy copies a blob between two locations. If the blob already exists in the target, the copy is skipped. A server side cross repository blob mount is attempted.

func (*RegClient) BlobDelete

func (rc *RegClient) BlobDelete(ctx context.Context, r ref.Ref, d descriptor.Descriptor) error

BlobDelete removes a blob from the registry. This method should only be used to repair a damaged registry. Typically a server side garbage collection should be used to purge unused blobs.

func (*RegClient) BlobGet

func (rc *RegClient) BlobGet(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.Reader, error)

BlobGet retrieves a blob, returning a reader. This reader must be closed to free up resources that limit concurrent pulls.

func (*RegClient) BlobGetOCIConfig

func (rc *RegClient) BlobGetOCIConfig(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.OCIConfig, error)

BlobGetOCIConfig retrieves an OCI config from a blob, automatically extracting the JSON.

func (*RegClient) BlobHead

func (rc *RegClient) BlobHead(ctx context.Context, r ref.Ref, d descriptor.Descriptor) (blob.Reader, error)

BlobHead is used to verify if a blob exists and is accessible.

func (*RegClient) BlobMount

func (rc *RegClient) BlobMount(ctx context.Context, refSrc ref.Ref, refTgt ref.Ref, d descriptor.Descriptor) error

BlobMount attempts to perform a server side copy/mount of the blob between repositories.

func (*RegClient) BlobPut

func (rc *RegClient) BlobPut(ctx context.Context, r ref.Ref, d descriptor.Descriptor, rdr io.Reader) (descriptor.Descriptor, error)

BlobPut uploads a blob to a repository. Descriptor is optional, leave size and digest to zero value if unknown. Reader must also be an io.Seeker to support chunked upload fallback.

This will attempt an anonymous blob mount first which some registries may support. It will then try doing a full put of the blob without chunking (most widely supported). If the full put fails, it will fall back to a chunked upload (useful for flaky networks).

func (*RegClient) Close

func (rc *RegClient) Close(ctx context.Context, r ref.Ref) error

Close is used to free resources associated with a reference. With ocidir, this may trigger a garbage collection process.

func (*RegClient) ImageCheckBase

func (rc *RegClient) ImageCheckBase(ctx context.Context, r ref.Ref, opts ...ImageOpts) error

ImageCheckBase returns nil if the base image is unchanged. A base image mismatch returns an error that wraps errs.ErrMismatch.

func (*RegClient) ImageConfig

func (rc *RegClient) ImageConfig(ctx context.Context, r ref.Ref, opts ...ImageOpts) (*blob.BOCIConfig, error)

ImageConfig returns the OCI config of a given image. Use ImageWithPlatform to select a platform from an Index or Manifest List.

func (*RegClient) ImageCopy

func (rc *RegClient) ImageCopy(ctx context.Context, refSrc ref.Ref, refTgt ref.Ref, opts ...ImageOpts) error

ImageCopy copies an image. This will retag an image in the same repository, only pushing and pulling the top level manifest. On the same registry, it will attempt to use cross-repository blob mounts to avoid pulling blobs. Blobs are only pulled when they don't exist on the target and a blob mount fails. Referrers are optionally copied recursively.

func (*RegClient) ImageExport

func (rc *RegClient) ImageExport(ctx context.Context, r ref.Ref, outStream io.Writer, opts ...ImageOpts) error

ImageExport exports an image to an output stream. The format is compatible with "docker load" if a single image is selected and not a manifest list. The ref must include a tag for exporting to docker (defaults to latest), and may also include a digest. The export is also formatted according to OCI Layout which supports multi-platform images. A tar file will be sent to outStream.

Resulting filesystem:

• oci-layout: created at top level, can be done at the start
• index.json: created at top level, single descriptor with org.opencontainers.image.ref.name annotation pointing to the tag
• manifest.json: created at top level, based on every layer added, only works for a single arch image
• blobs/$algo/$hash: each content addressable object (manifest, config, or layer), created recursively

func (*RegClient) ImageImport

func (rc *RegClient) ImageImport(ctx context.Context, r ref.Ref, rs io.ReadSeeker, opts ...ImageOpts) error

ImageImport pushes an image from a tar file (ImageExport) to a registry.

func (*RegClient) ManifestDelete

func (rc *RegClient) ManifestDelete(ctx context.Context, r ref.Ref, opts ...ManifestOpts) error

ManifestDelete removes a manifest, including all tags pointing to that registry. The reference must include the digest to delete (see TagDelete for deleting a tag). All tags pointing to the manifest will be deleted.

func (*RegClient) ManifestGet

func (rc *RegClient) ManifestGet(ctx context.Context, r ref.Ref, opts ...ManifestOpts) (manifest.Manifest, error)

ManifestGet retrieves a manifest.

func (*RegClient) ManifestHead

func (rc *RegClient) ManifestHead(ctx context.Context, r ref.Ref, opts ...ManifestOpts) (manifest.Manifest, error)

ManifestHead queries for the existence of a manifest and returns metadata (digest, media-type, size).

func (*RegClient) ManifestPut

func (rc *RegClient) ManifestPut(ctx context.Context, r ref.Ref, m manifest.Manifest, opts ...ManifestOpts) error

ManifestPut pushes a manifest. Any descriptors referenced by the manifest typically need to be pushed first.

func (*RegClient) Ping

func (rc *RegClient) Ping(ctx context.Context, r ref.Ref) (ping.Result, error)

Ping verifies access to a registry or equivalent.

func (*RegClient) ReferrerList

func (rc *RegClient) ReferrerList(ctx context.Context, rSubject ref.Ref, opts ...scheme.ReferrerOpts) (referrer.ReferrerList, error)

ReferrerList retrieves a list of referrers to a manifest. The descriptor list should contain manifests that each have a subject field matching the requested ref.

func (*RegClient) RepoList

func (rc *RegClient) RepoList(ctx context.Context, hostname string, opts ...scheme.RepoOpts) (*repo.RepoList, error)

RepoList returns a list of repositories on a registry. Note the underlying "_catalog" API is not supported on many cloud registries.

func (*RegClient) TagDelete

func (rc *RegClient) TagDelete(ctx context.Context, r ref.Ref) error

TagDelete deletes a tag from the registry. Since there's no API for this, you'd want to normally just delete the manifest. However multiple tags may point to the same manifest, so instead you must: 1. Make a manifest, for this we put a few labels and timestamps to be unique. 2. Push that manifest to the tag. 3. Delete the digest for that new manifest that is only used by that tag.

func (*RegClient) TagList

func (rc *RegClient) TagList(ctx context.Context, r ref.Ref, opts ...scheme.TagOpts) (*tag.List, error)

TagList returns a tag list from a repository