Merge pull request #1910 from hashicorp/f-detect-dupe-addrs

Print a helpful message re: duplicate addresses

command/agent/command.go

@@ -192,6 +192,12 @@ func (c *Command) readConfig() *Config {
 		return nil
 	}
 
+	// Ensure all endpoints are unique
+	if err := config.verifyUniqueListeners(); err != nil {
+		c.Ui.Error(fmt.Sprintf("All listening endpoints must be unique: %s", err))
+		return nil
+	}
+
 	// Check the data dir for signs of an un-migrated Consul 0.5.x or older
 	// server. Consul refuses to start if this is present to protect a server
 	// with existing data from starting on a fresh data set.
@@ -301,6 +307,67 @@ func (c *Command) readConfig() *Config {
 	return config
 }
 
+// verifyUniqueListeners checks to see if an address was used more than once in
+// the config
+func (config *Config) verifyUniqueListeners() error {
+	type key struct {
+		host string
+		port int
+	}
+	const numUniqueAddrs = 7
+	m := make(map[key]string, numUniqueAddrs)
+
+	testFunc := func(k key, descr string) error {
+		if k.host == "" {
+			k.host = "0.0.0.0"
+		} else if strings.HasPrefix(k.host, "unix") {
+			// Don't compare ports on unix sockets
+			k.port = 0
+		}
+		if k.host == "0.0.0.0" && k.port <= 0 {
+			return nil
+		}
+
+		v, ok := m[k]
+		if ok {
+			return fmt.Errorf("%s address already configured for %s", descr, v)
+		}
+		m[k] = descr
+
+		return nil
+	}
+
+	if err := testFunc(key{config.Addresses.RPC, config.Ports.RPC}, "RPC"); err != nil {
+		return err
+	}
+
+	if err := testFunc(key{config.Addresses.DNS, config.Ports.DNS}, "DNS"); err != nil {
+		return err
+	}
+
+	if err := testFunc(key{config.Addresses.HTTP, config.Ports.HTTP}, "HTTP"); err != nil {
+		return err
+	}
+
+	if err := testFunc(key{config.Addresses.HTTPS, config.Ports.HTTPS}, "HTTPS"); err != nil {
+		return err
+	}
+
+	if err := testFunc(key{config.AdvertiseAddr, config.Ports.Server}, "Server RPC"); err != nil {
+		return err
+	}
+
+	if err := testFunc(key{config.AdvertiseAddr, config.Ports.SerfLan}, "Serf LAN"); err != nil {
+		return err
+	}
+
+	if err := testFunc(key{config.AdvertiseAddr, config.Ports.SerfWan}, "Serf WAN"); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // setupLoggers is used to setup the logGate, logWriter, and our logOutput
 func (c *Command) setupLoggers(config *Config) (*GatedWriter, *logWriter, io.Writer) {
 	// Setup logging. First create the gated log writer, which will

command/agent/config_test.go

@@ -989,6 +989,42 @@ func TestDecodeConfig_Services(t *testing.T) {
 	}
 }
 
+func TestDecodeConfig_verifyUniqueListeners(t *testing.T) {
+	tests := []struct {
+		name string
+		cfg  string
+		pass bool
+	}{
+		{
+			"http_rpc1",
+			`{"addresses": {"http": "0.0.0.0", "rpc": "127.0.0.1"}, "ports": {"rpc": 8000, "dns": 8000}}`,
+			true,
+		},
+		{
+			"http_rpc IP identical",
+			`{"addresses": {"http": "0.0.0.0", "rpc": "0.0.0.0"}, "ports": {"rpc": 8000, "dns": 8000}}`,
+			false,
+		},
+		{
+			"http_rpc unix identical (diff ports)",
+			`{"addresses": {"http": "unix:///tmp/.consul.sock", "rpc": "unix:///tmp/.consul.sock"}, "ports": {"rpc": 8000, "dns": 8001}}`,
+			false,
+		},
+	}
+
+	for _, test := range tests {
+		config, err := DecodeConfig(bytes.NewReader([]byte(test.cfg)))
+		if err != nil {
+			t.Fatalf("err: %s %s", test.name, err)
+		}
+
+		err = config.verifyUniqueListeners()
+		if (err != nil && test.pass) || (err == nil && !test.pass) {
+			t.Errorf("err: %s should have %v: %v: %v", test.name, test.pass, test.cfg, err)
+		}
+	}
+}
+
 func TestDecodeConfig_Checks(t *testing.T) {
 	input := `{
 		"checks": [