Added auto-detection of IPv6 on linux

Author: ewoutp

main.go

@@ -35,13 +35,15 @@ import (
 	"syscall"
 	"time"
 
-	_ "github.com/arangodb-helper/arangodb/client"
-	service "github.com/arangodb-helper/arangodb/service"
 	homedir "github.com/mitchellh/go-homedir"
 	logging "github.com/op/go-logging"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
+
+	_ "github.com/arangodb-helper/arangodb/client"
+	"github.com/arangodb-helper/arangodb/pkg/net"
+	service "github.com/arangodb-helper/arangodb/service"
 )
 
 // Configuration data with defaults:
@@ -116,7 +118,7 @@ func init() {
 	f.BoolVar(&allPortOffsetsUnique, "starter.unique-port-offsets", false, "If set, all peers will get a unique port offset. If false (default) only portOffset+peerAddress pairs will be unique.")
 	f.StringVar(&dataDir, "starter.data-dir", getEnvVar("DATA_DIR", "."), "directory to store all data the starter generates (and holds actual database directories)")
 	f.BoolVar(&debugCluster, "starter.debug-cluster", getEnvVar("DEBUG_CLUSTER", "") != "", "If set, log more information to debug a cluster")
-	f.BoolVar(&disableIPv6, "starter.disable-ipv6", false, "If set, no IPv6 notation will be used. Use this only when IPv6 address family is disabled")
+	f.BoolVar(&disableIPv6, "starter.disable-ipv6", !net.IsIPv6Supported(), "If set, no IPv6 notation will be used. Use this only when IPv6 address family is disabled")
 
 	f.BoolVar(&verbose, "log.verbose", false, "Turn on debug logging")
 

pkg/net/ipv6.go

@@ -0,0 +1,33 @@
+//
+// DISCLAIMER
+//
+// Copyright 2017 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+// Author Ewout Prangsma
+//
+
+// +build !linux
+
+package net
+
+// IsIPv6Supported returns true when IPv6 support is available,
+// false when it is not.
+// Note that it is not possible on all platforms to properly
+// detect IPv6 support.
+func IsIPv6Supported() bool {
+	return true
+}

pkg/net/ipv6_linux.go

@@ -0,0 +1,36 @@
+//
+// DISCLAIMER
+//
+// Copyright 2017 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+// Author Ewout Prangsma
+//
+
+package net
+
+import "os"
+
+// IsIPv6Supported returns true when IPv6 support is available,
+// false when it is not.
+// Note that it is not possible on all platforms to properly
+// detect IPv6 support.
+func IsIPv6Supported() bool {
+	if _, err := os.Stat("/proc/net/if_inet6"); err == nil {
+		return true
+	}
+	return false
+}