restic: if S3, get bucket's region up-front

Signed-off-by: Steve Kriss <steve@heptio.com>

pkg/cloudprovider/aws/helpers.go

@@ -0,0 +1,53 @@
+/*
+Copyright 2018 the Heptio Ark contributors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package aws
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+
+	"github.com/aws/aws-sdk-go/aws/endpoints"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/s3/s3manager"
+)
+
+// GetBucketRegion returns the AWS region that a bucket is in, or an error
+// if the region cannot be determined.
+func GetBucketRegion(bucket string) (string, error) {
+	var region string
+
+	session, err := session.NewSession()
+	if err != nil {
+		return "", errors.WithStack(err)
+	}
+
+	for _, partition := range endpoints.DefaultPartitions() {
+		for regionHint := range partition.Regions() {
+			region, _ = s3manager.GetBucketRegion(context.Background(), session, bucket, regionHint)
+
+			// we only need to try a single region hint per partition, so break after the first
+			break
+		}
+
+		if region != "" {
+			return region, nil
+		}
+	}
+
+	return "", errors.New("unable to determine bucket's region")
+}

pkg/cloudprovider/aws/object_store.go

@@ -17,14 +17,12 @@ limitations under the License.
 package aws
 
 import (
-	"context"
 	"io"
 	"strconv"
 	"time"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/endpoints"
-	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/aws/aws-sdk-go/service/s3/s3manager"
 	"github.com/pkg/errors"
@@ -49,30 +47,6 @@ func NewObjectStore() cloudprovider.ObjectStore {
 	return &objectStore{}
 }
 
-func getBucketRegion(bucket string) (string, error) {
-	var region string
-
-	session, err := session.NewSession()
-	if err != nil {
-		return "", errors.WithStack(err)
-	}
-
-	for _, partition := range endpoints.DefaultPartitions() {
-		for regionHint := range partition.Regions() {
-			region, _ = s3manager.GetBucketRegion(context.Background(), session, bucket, regionHint)
-
-			// we only need to try a single region hint per partition, so break after the first
-			break
-		}
-
-		if region != "" {
-			return region, nil
-		}
-	}
-
-	return "", errors.New("unable to determine bucket's region")
-}
-
 func (o *objectStore) Init(config map[string]string) error {
 	var (
 		region              = config[regionKey]
@@ -100,7 +74,7 @@ func (o *objectStore) Init(config map[string]string) error {
 	if s3URL == "" && region == "" {
 		var err error
 
-		region, err = getBucketRegion(bucket)
+		region, err = GetBucketRegion(bucket)
 		if err != nil {
 			return err
 		}

pkg/restic/config.go

@@ -21,6 +21,7 @@ import (
 	"strings"
 
 	arkv1api "github.com/heptio/ark/pkg/apis/ark/v1"
+	"github.com/heptio/ark/pkg/cloudprovider/aws"
 )
 
 type BackendType string
@@ -34,22 +35,9 @@ const (
 // getRepoPrefix returns the prefix of the value of the --repo flag for
 // restic commands, i.e. everything except the "/<repo-name>".
 func getRepoPrefix(config arkv1api.ObjectStorageProviderConfig) string {
-	if BackendType(config.Name) == AWSBackend {
-		var url string
-		switch {
-		// non-AWS, S3-compatible object store
-		case config.Config["s3Url"] != "":
-			url = config.Config["s3Url"]
-		default:
-			url = "s3.amazonaws.com"
-		}
-
-		return fmt.Sprintf("s3:%s/%s", url, config.ResticLocation)
-	}
-
 	var (
-		parts        = strings.SplitN(config.ResticLocation, "/", 2)
-		bucket, path string
+		parts                = strings.SplitN(config.ResticLocation, "/", 2)
+		bucket, path, prefix string
 	)
 
 	if len(parts) >= 1 {
@@ -59,8 +47,24 @@ func getRepoPrefix(config arkv1api.ObjectStorageProviderConfig) string {
 		path = parts[1]
 	}
 
-	var prefix string
 	switch BackendType(config.Name) {
+	case AWSBackend:
+		var url string
+		switch {
+		// non-AWS, S3-compatible object store
+		case config.Config["s3Url"] != "":
+			url = config.Config["s3Url"]
+		default:
+			region, err := aws.GetBucketRegion(bucket)
+			if err != nil {
+				url = "s3.amazonaws.com"
+				break
+			}
+
+			url = fmt.Sprintf("s3-%s.amazonaws.com", region)
+		}
+
+		return fmt.Sprintf("s3:%s/%s", url, config.ResticLocation)
 	case AzureBackend:
 		prefix = "azure"
 	case GCPBackend: