distribution: add GetRepository(), un-export NewV2Repository, ValidateRepoName

These were only exported to facilitate ImageService.GetRepository() (used for
the `GET /distribution/{name:.*}/json` endpoint.

Moving the core functionality of that to the distribution package makes it
more consistent with (e.g.) "pull" operations, and allows us to keep more things
internal.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

7 files changed, 43 insertions, 9 deletions

diff --git a/distribution/pull.go b/distribution/pull.go
index baba845264..cb60f62b6f 100644
--- a/distribution/pull.go
+++ b/distribution/pull.go
@@ -38,7 +38,7 @@ func Pull(ctx context.Context, ref reference.Named, config *ImagePullConfig, loc
 	}
 
 	// makes sure name is not `scratch`
-	if err := ValidateRepoName(repoInfo.Name); err != nil {
+	if err := validateRepoName(repoInfo.Name); err != nil {
 		return err
 	}
 
@@ -112,8 +112,8 @@ func writeStatus(requestedTag string, out progress.Output, layersDownloaded bool
 	}
 }
 
-// ValidateRepoName validates the name of a repository.
-func ValidateRepoName(name reference.Named) error {
+// validateRepoName validates the name of a repository.
+func validateRepoName(name reference.Named) error {
 	if reference.FamiliarName(name) == api.NoBaseImageSpecifier {
 		return errors.WithStack(reservedNameError(api.NoBaseImageSpecifier))
 	}
diff --git a/distribution/pull_v2.go b/distribution/pull_v2.go
index 0495ab4146..37ced60d43 100644
--- a/distribution/pull_v2.go
+++ b/distribution/pull_v2.go
@@ -63,7 +63,7 @@ type puller struct {
 
 func (p *puller) pull(ctx context.Context, ref reference.Named) (err error) {
 	// TODO(tiborvass): was ReceiveTimeout
-	p.repo, err = NewV2Repository(ctx, p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
+	p.repo, err = newRepository(ctx, p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
 	if err != nil {
 		logrus.Warnf("Error getting v2 registry: %v", err)
 		return err
diff --git a/distribution/pull_v2_test.go b/distribution/pull_v2_test.go
index a080c9eadf..a4824dff08 100644
--- a/distribution/pull_v2_test.go
+++ b/distribution/pull_v2_test.go
@@ -359,7 +359,7 @@ func testNewPuller(t *testing.T, rawurl string) *puller {
 	}
 
 	p := newPuller(endpoint, repoInfo, imagePullConfig, nil)
-	p.repo, err = NewV2Repository(context.Background(), p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
+	p.repo, err = newRepository(context.Background(), p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/distribution/push_v2.go b/distribution/push_v2.go
index 24824709ee..f5168f836b 100644
--- a/distribution/push_v2.go
+++ b/distribution/push_v2.go
@@ -60,7 +60,7 @@ type pushState struct {
 func (p *pusher) push(ctx context.Context) (err error) {
 	p.pushState.remoteLayers = make(map[layer.DiffID]distribution.Descriptor)
 
-	p.repo, err = NewV2Repository(ctx, p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "push", "pull")
+	p.repo, err = newRepository(ctx, p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "push", "pull")
 	p.pushState.hasAuthInfo = p.config.AuthConfig.RegistryToken != "" || (p.config.AuthConfig.Username != "" && p.config.AuthConfig.Password != "")
 	if err != nil {
 		logrus.Debugf("Error getting v2 registry: %v", err)
diff --git a/distribution/registry.go b/distribution/registry.go
index 904ffff2be..7ff01b5d92 100644
--- a/distribution/registry.go
+++ b/distribution/registry.go
@@ -53,10 +53,10 @@ func init() {
 	}
 }
 
-// NewV2Repository returns a repository (v2 only). It creates an HTTP transport
+// newRepository returns a repository (v2 only). It creates an HTTP transport
 // providing timeout settings and authentication support, and also verifies the
 // remote API version.
-func NewV2Repository(
+func newRepository(
 	ctx context.Context, repoInfo *registry.RepositoryInfo, endpoint registry.APIEndpoint,
 	metaHeaders http.Header, authConfig *types.AuthConfig, actions ...string,
 ) (repo distribution.Repository, err error) {
diff --git a/distribution/registry_unit_test.go b/distribution/registry_unit_test.go
index df9e12a99a..c803577173 100644
--- a/distribution/registry_unit_test.go
+++ b/distribution/registry_unit_test.go
@@ -70,7 +70,7 @@ func testTokenPassThru(t *testing.T, ts *httptest.Server) {
 	}
 	p := newPuller(endpoint, repoInfo, imagePullConfig, nil)
 	ctx := context.Background()
-	p.repo, err = NewV2Repository(ctx, p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
+	p.repo, err = newRepository(ctx, p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/distribution/repository.go b/distribution/repository.go
new file mode 100644
index 0000000000..f424c24b65
--- /dev/null
+++ b/distribution/repository.go
@@ -0,0 +1,34 @@
+package distribution
+
+import (
+	"context"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/reference"
+	"github.com/docker/docker/errdefs"
+)
+
+// GetRepository returns a repository from the registry.
+func GetRepository(ctx context.Context, ref reference.Named, config *ImagePullConfig) (repository distribution.Repository, lastError error) {
+	repoInfo, err := config.RegistryService.ResolveRepository(ref)
+	if err != nil {
+		return nil, errdefs.InvalidParameter(err)
+	}
+	// makes sure name is not empty or `scratch`
+	if err := validateRepoName(repoInfo.Name); err != nil {
+		return nil, errdefs.InvalidParameter(err)
+	}
+
+	endpoints, err := config.RegistryService.LookupPullEndpoints(reference.Domain(repoInfo.Name))
+	if err != nil {
+		return nil, err
+	}
+
+	for _, endpoint := range endpoints {
+		repository, lastError = newRepository(ctx, repoInfo, endpoint, nil, config.AuthConfig, "pull")
+		if lastError == nil {
+			break
+		}
+	}
+	return repository, lastError
+}