Use interface name instead of cluster name

The cluster name option is not required anymore and
removed, the interface name is used to name the cluster
directly. For backward compatibility, the old path for storing
cluster state is tried as a fallback when loading.

README.md

@@ -137,7 +137,6 @@ All options can be passed either as command-line flags or environment variables:
 | `--cluster-key KEY` | WESHER_CLUSTER_KEY | shared key for cluster membership; must be 32 bytes base64 encoded; will be generated if not provided | autogenerated/loaded |
 | `--join HOST,...` | WESHER_JOIN | comma separated list of hostnames or IP addresses to existing cluster members; if not provided, will attempt resuming any known state or otherwise wait for further members |  |
 | `--init` | WESHER_INIT | whether to explicitly (re)initialize the cluster; any known state from previous runs will be forgotten | `false` |
-| `--cluster-name` | WESHER_CLUSTER_NAME | Identifier for the wesher cluster; can be used to peer with multiple clusters | `default` |
 | `--bind-addr ADDR` | WESHER_BIND_ADDR | IP address to bind to for cluster membership (cannot be used with --bind-iface) | autodetected |
 | `--bind-iface IFACE` | WESHER_BIND_IFACE | Interface to bind to for cluster membership (cannot be used with --bind-addr)|  |
 | `--cluster-port PORT` | WESHER_CLUSTER_PORT | port used for membership gossip traffic (both TCP and UDP); must be the same across cluster | `7946` |
@@ -147,6 +146,16 @@ All options can be passed either as command-line flags or environment variables:
 | `--no-etc-hosts` | WESHER_NO_ETC_HOSTS | whether to skip writing hosts entries for each node in mesh | `false` |
 | `--log-level LEVEL` | WESHER_LOG_LEVEL | set the verbosity (one of debug/info/warn/error) | `warn` |
 
+## Running multiple clusters
+
+Wesher supports having a node be a member of multiple clusters. The following settings must be explicitely set to non-conflicting values:
+- `--interface`, so that wireguard does not mix up traffic, the interface name is also used for naming the state file
+- `--cluster-port` or `--bind-addr` or `--bind-iface`, so that wesher can properly bind to its port
+- `--wireguard-port`, so that wireguard can properly bind to its port
+
+One should also use different overlay networks. Even though using the same network on different devices will work in some cases, it is not the intended use.
+
+Finally, one should use different cluster keys for different clusters, as a security best practice.
 
 ## Security considerations
 

cluster/state.go

@@ -17,10 +17,12 @@ type state struct {
 	Nodes      []common.Node
 }
 
-var defaultStatePath = "/var/lib/wesher/%s.json"
+var statePathTemplate = "/var/lib/wesher/%s.json"
+
+const deprecatedStatePath = "/var/lib/wesher/state.json"
 
 func (s *state) save(clusterName string) error {
-	statePath := fmt.Sprintf(defaultStatePath, clusterName)
+	statePath := fmt.Sprintf(statePathTemplate, clusterName)
 	if err := os.MkdirAll(path.Dir(statePath), 0700); err != nil {
 		return err
 	}
@@ -34,14 +36,22 @@ func (s *state) save(clusterName string) error {
 }
 
 func loadState(cs *state, clusterName string) {
-	statePath := fmt.Sprintf(defaultStatePath, clusterName)
+	statePath := fmt.Sprintf(statePathTemplate, clusterName)
 	content, err := ioutil.ReadFile(statePath)
+	if err != nil {
+		// try the deprecated pre 0.3 state path, it will later
+		// be saved to the proper path
+		if os.IsNotExist(err) {
+			content, err = ioutil.ReadFile(deprecatedStatePath)
+		}
+
 		if err != nil {
 			if !os.IsNotExist(err) {
 				logrus.Warnf("could not open state in %s: %s", statePath, err)
 			}
 			return
 		}
+	}
 
 	// avoid partially unmarshalled content by using a temp var
 	csTmp := &state{}

cluster/state_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func Test_state_save_soad(t *testing.T) {
-	defaultStatePath = "/tmp/%s.json"
+	statePathTemplate = "/tmp/%s.json"
 	key := "abcdefghijklmnopqrstuvwxyzABCDEF"
 	node := common.Node{
 		Name: "node",

config.go

@@ -14,7 +14,6 @@ type config struct {
 	ClusterKey    []byte   `id:"cluster-key" desc:"shared key for cluster membership; must be 32 bytes base64 encoded; will be generated if not provided"`
 	Join          []string `desc:"comma separated list of hostnames or IP addresses to existing cluster members; if not provided, will attempt resuming any known state or otherwise wait for further members."`
 	Init          bool     `desc:"whether to explicitly (re)initialize the cluster; any known state from previous runs will be forgotten"`
-	ClusterName   string   `id:"cluster-name" desc:"identifier for the wesher cluster; can be used to peer with multiple clusters" default:"default"`
 	BindAddr      string   `id:"bind-addr" desc:"IP address to bind to for cluster membership traffic (cannot be used with --bind-iface)"`
 	BindIface     string   `id:"bind-iface" desc:"Interface to bind to for cluster membership traffic (cannot be used with --bind-addr)"`
 	ClusterPort   int      `id:"cluster-port" desc:"port used for membership gossip traffic (both TCP and UDP); must be the same across cluster" default:"7946"`

main.go

@@ -35,7 +35,7 @@ func main() {
 	logrus.SetLevel(logLevel)
 
 	// Create the wireguard and cluster configuration
-	cluster, err := cluster.New(config.ClusterName, config.Init, config.ClusterKey, config.BindAddr, config.ClusterPort, config.UseIPAsName)
+	cluster, err := cluster.New(config.Interface, config.Init, config.ClusterKey, config.BindAddr, config.ClusterPort, config.UseIPAsName)
 	if err != nil {
 		logrus.WithError(err).Fatal("could not create cluster")
 	}
@@ -46,7 +46,7 @@ func main() {
 
 	// Prepare the /etc/hosts writer
 	hostsFile := &etchosts.EtcHosts{
-		Banner: "# ! managed automatically by wesher " + config.ClusterName,
+		Banner: "# ! managed automatically by wesher interface " + config.Interface,
 		Logger: logrus.StandardLogger(),
 	}
 

tests/e2e.sh

@@ -101,8 +101,8 @@ test_cluster_simultaneous_start() {
 }
 
 test_multiple_clusters_restart() {
-    cluster1='--cluster-port 7946 --wireguard-port 51820 --cluster-name cluster1 --interface wgoverlay --overlay-net 10.10.0.0/16'
+    cluster1='--cluster-port 7946 --wireguard-port 51820 --interface wgoverlay --overlay-net 10.10.0.0/16'
-    cluster2='--cluster-port 7947 --wireguard-port 51821 --cluster-name cluster2 --interface wgoverlay2 --overlay-net 10.11.0.0/16'
+    cluster2='--cluster-port 7947 --wireguard-port 51821 --interface wgoverlay2 --overlay-net 10.11.0.0/16'
     setup_wireguard='wireguard-go wgoverlay2 2>/dev/null >/dev/null'
     join_cluster2="nohup /app/wesher --cluster-key 'ILICZ3yBMCGAWNIq5Pn0bewBVimW3Q2yRVJ/Be+b1Uc=' --join test2-orig $cluster2 2>/dev/null &"