Merge pull request #2557 from hashicorp/sethvargo/safer_server

Use a random port instead of idx in testutil

testutil/server.go

@@ -23,15 +23,11 @@ import (
 	"os"
 	"os/exec"
 	"strings"
-	"sync/atomic"
 
 	"github.com/hashicorp/consul/consul/structs"
 	"github.com/hashicorp/go-cleanhttp"
 )
 
-// offset is used to atomically increment the port numbers.
-var offset uint64
-
 // TestPerformanceConfig configures the performance parameters.
 type TestPerformanceConfig struct {
 	RaftMultiplier uint `json:"raft_multiplier,omitempty"`
@@ -82,10 +78,8 @@ type ServerConfigCallback func(c *TestServerConfig)
 // defaultServerConfig returns a new TestServerConfig struct
 // with all of the listen ports incremented by one.
 func defaultServerConfig() *TestServerConfig {
-	idx := int(atomic.AddUint64(&offset, 1))
-
 	return &TestServerConfig{
-		NodeName:          fmt.Sprintf("node%d", idx),
+		NodeName:          fmt.Sprintf("node%d", randomPort()),
 		DisableCheckpoint: true,
 		Performance: &TestPerformanceConfig{
 			RaftMultiplier: 1,
@@ -96,16 +90,26 @@ func defaultServerConfig() *TestServerConfig {
 		Bind:      "127.0.0.1",
 		Addresses: &TestAddressConfig{},
 		Ports: &TestPortConfig{
-			DNS:     20000 + idx,
-			HTTP:    21000 + idx,
-			RPC:     22000 + idx,
-			SerfLan: 23000 + idx,
-			SerfWan: 24000 + idx,
-			Server:  25000 + idx,
+			DNS:     randomPort(),
+			HTTP:    randomPort(),
+			RPC:     randomPort(),
+			SerfLan: randomPort(),
+			SerfWan: randomPort(),
+			Server:  randomPort(),
 		},
 	}
 }
 
+// randomPort asks the kernel for a random port to use.
+func randomPort() int {
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		panic(err)
+	}
+	defer l.Close()
+	return l.Addr().(*net.TCPAddr).Port
+}
+
 // TestService is used to serialize a service definition.
 type TestService struct {
 	ID      string   `json:",omitempty"`