go.mod: change imports to github.com/distribution/distribution/v3

Go 1.13 and up enforce import paths to be versioned if a project
contains a go.mod and has released v2 or up.

The current v2.x branches (and releases) do not yet have a go.mod,
and therefore are still allowed to be imported with a non-versioned
import path (go modules add a `+incompatible` annotation in that case).

However, now that this project has a `go.mod` file, incompatible
import paths will not be accepted by go modules, and attempting
to use code from this repository will fail.

This patch uses `v3` for the import-paths (not `v2`), because changing
import paths itself is a breaking change, which means that  the
next release should increment the "major" version to comply with
SemVer (as go modules dictate).

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

registry/storage/cache/cache.go

@@ -5,7 +5,7 @@ package cache
 import (
 	"fmt"
 
-	"github.com/docker/distribution"
+	"github.com/distribution/distribution/v3"
 )
 
 // BlobDescriptorCacheProvider provides repository scoped

registry/storage/cache/cache_test.go

@@ -5,7 +5,7 @@ import (
 	"errors"
 	"testing"
 
-	"github.com/docker/distribution"
+	"github.com/distribution/distribution/v3"
 	digest "github.com/opencontainers/go-digest"
 )
 

registry/storage/cache/cachecheck/suite.go

@@ -5,8 +5,8 @@ import (
 	"reflect"
 	"testing"
 
-	"github.com/docker/distribution"
-	"github.com/docker/distribution/registry/storage/cache"
+	"github.com/distribution/distribution/v3"
+	"github.com/distribution/distribution/v3/registry/storage/cache"
 	"github.com/opencontainers/go-digest"
 )
 

registry/storage/cache/cachedblobdescriptorstore.go

@@ -3,9 +3,9 @@ package cache
 import (
 	"context"
 
-	"github.com/docker/distribution"
-	dcontext "github.com/docker/distribution/context"
-	prometheus "github.com/docker/distribution/metrics"
+	"github.com/distribution/distribution/v3"
+	dcontext "github.com/distribution/distribution/v3/context"
+	prometheus "github.com/distribution/distribution/v3/metrics"
 	"github.com/opencontainers/go-digest"
 )
 

registry/storage/cache/memory/memory.go

@@ -4,9 +4,9 @@ import (
 	"context"
 	"sync"
 
-	"github.com/docker/distribution"
-	"github.com/docker/distribution/reference"
-	"github.com/docker/distribution/registry/storage/cache"
+	"github.com/distribution/distribution/v3"
+	"github.com/distribution/distribution/v3/reference"
+	"github.com/distribution/distribution/v3/registry/storage/cache"
 	"github.com/opencontainers/go-digest"
 )
 

registry/storage/cache/memory/memory_test.go

@@ -3,7 +3,7 @@ package memory
 import (
 	"testing"
 
-	"github.com/docker/distribution/registry/storage/cache/cachecheck"
+	"github.com/distribution/distribution/v3/registry/storage/cache/cachecheck"
 )
 
 // TestInMemoryBlobInfoCache checks the in memory implementation is working

registry/storage/cache/metrics/prom.go

@@ -4,9 +4,9 @@ import (
 	"context"
 	"time"
 
-	"github.com/docker/distribution"
-	prometheus "github.com/docker/distribution/metrics"
-	"github.com/docker/distribution/registry/storage/cache"
+	"github.com/distribution/distribution/v3"
+	prometheus "github.com/distribution/distribution/v3/metrics"
+	"github.com/distribution/distribution/v3/registry/storage/cache"
 	"github.com/docker/go-metrics"
 	"github.com/opencontainers/go-digest"
 )

registry/storage/cache/redis/redis.go

@@ -4,10 +4,10 @@ import (
 	"context"
 	"fmt"
 
-	"github.com/docker/distribution"
-	"github.com/docker/distribution/reference"
-	"github.com/docker/distribution/registry/storage/cache"
-	"github.com/docker/distribution/registry/storage/cache/metrics"
+	"github.com/distribution/distribution/v3"
+	"github.com/distribution/distribution/v3/reference"
+	"github.com/distribution/distribution/v3/registry/storage/cache"
+	"github.com/distribution/distribution/v3/registry/storage/cache/metrics"
 	"github.com/gomodule/redigo/redis"
 	"github.com/opencontainers/go-digest"
 )

registry/storage/cache/redis/redis_test.go

@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/docker/distribution/registry/storage/cache/cachecheck"
+	"github.com/distribution/distribution/v3/registry/storage/cache/cachecheck"
 	"github.com/gomodule/redigo/redis"
 )