Support custom endpoint for S3 (grafana#1476)

Signed-off-by: mizeng <mizeng@ebaysf.com>

aws/dynamodb_storage_client.go

@@ -126,7 +126,8 @@ func (cfg *DynamoDBConfig) RegisterFlags(f *flag.FlagSet) {
 // StorageConfig specifies config for storing data on AWS.
 type StorageConfig struct {
 	DynamoDBConfig
-	S3 flagext.URLValue
+	S3               flagext.URLValue
+	S3ForcePathStyle bool
 }
 
 // RegisterFlags adds the flags required to config this to the given FlagSet
@@ -135,6 +136,7 @@ func (cfg *StorageConfig) RegisterFlags(f *flag.FlagSet) {
 
 	f.Var(&cfg.S3, "s3.url", "S3 endpoint URL with escaped Key and Secret encoded. "+
 		"If only region is specified as a host, proper endpoint will be deduced. Use inmemory:///<bucket-name> to use a mock in-memory implementation.")
+	f.BoolVar(&cfg.S3ForcePathStyle, "s3.force-path-style", false, "Set this to `true` to force the request to use path-style addressing.")
 }
 
 type dynamoDBStorageClient struct {

aws/s3_storage_client.go

@@ -47,6 +47,8 @@ func NewS3ObjectClient(cfg StorageConfig, schemaCfg chunk.SchemaConfig) (chunk.O
 		return nil, err
 	}
 
+	s3Config = s3Config.WithS3ForcePathStyle(cfg.S3ForcePathStyle) // support for Path Style S3 url if has the flag
+
 	s3Config = s3Config.WithMaxRetries(0) // We do our own retries, so we can monitor them
 	s3Client := s3.New(session.New(s3Config))
 	bucketName := strings.TrimPrefix(cfg.S3.URL.Path, "/")