Add retention flag specific for s3

* Add retention flag specific for s3
* Add retention for the unit tests:

Signed-off-by: Vitor Savian <vitor.savian@suse.com>

pkg/cli/cmds/etcd_snapshot.go

@@ -124,6 +124,13 @@ var EtcdSnapshotFlags = []cli.Flag{
 		Destination: &ServerConfig.EtcdS3Region,
 		Value:       "us-east-1",
 	},
+	&cli.IntFlag{
+		Name:        "s3-retention",
+		Aliases:     []string{"etcd-s3-retention"},
+		Usage:       "(db) Number of s3 snapshots to retain.",
+		Destination: &ServerConfig.EtcdS3Retention,
+		Value:       defaultSnapshotRentention,
+	},
 	&cli.StringFlag{
 		Name:        "s3-folder",
 		Aliases:     []string{"etcd-s3-folder"},

pkg/cli/cmds/server.go

@@ -105,6 +105,7 @@ type Server struct {
 	EtcdS3SecretKey          string
 	EtcdS3SessionToken       string
 	EtcdS3BucketName         string
+	EtcdS3Retention          int
 	EtcdS3BucketLookupType   string
 	EtcdS3Region             string
 	EtcdS3Folder             string
@@ -480,6 +481,12 @@ var ServerFlags = []cli.Flag{
 		Usage:       "(db) S3 folder",
 		Destination: &ServerConfig.EtcdS3Folder,
 	},
+	&cli.IntFlag{
+		Name:        "etcd-s3-retention",
+		Usage:       "(db) S3 retention limit",
+		Destination: &ServerConfig.EtcdS3Retention,
+		Value:       defaultSnapshotRentention,
+	},
 	&cli.StringFlag{
 		Name:        "etcd-s3-proxy",
 		Usage:       "(db) Proxy server to use when connecting to S3, overriding any proxy-releated environment variables",