Add some randomness to the ports used

Signed-off-by: Matt Lord <mattalord@gmail.com>

Author: mattlord

go/test/endtoend/vreplication/cluster_test.go

@@ -297,11 +297,17 @@ func downloadDBTypeVersion(dbType string, majorVersion string, path string) erro
 }
 
 func getClusterConfig(idx int, dataRootDir string) *ClusterConfig {
+	offset := 0
+	if !debugMode {
+		// Add some randomness to the ports so that multiple tests can run in
+		// parallel on the same host.
+		offset = (idx + 1) * rand.IntN(1000)
+	}
 	basePort := 15000
 	etcdPort := 2379
 
-	basePort += idx * 10000
-	etcdPort += idx * 10000
+	basePort += (idx * 10000) + offset
+	etcdPort += (idx * 10000) + offset
 	if _, err := os.Stat(dataRootDir); os.IsNotExist(err) {
 		os.Mkdir(dataRootDir, 0700)
 	}