add --init option for explicit cluster reset

README.md

@@ -83,6 +83,7 @@ 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` |
 | `--bind-addr ADDR` | WESHER_BIND_ADDR | IP address to bind to for cluster membership | autodetected |
 | `--cluster-port PORT` | WESHER_CLUSTER_PORT | port used for membership gossip traffic (both TCP and UDP); must be the same across cluster | `7946` |
 | `--wireguard-port PORT` | WESHER_WIREGUARD_PORT | port used for wireguard traffic (UDP); must be the same across cluster | `51820` |

cluster.go

@@ -43,7 +43,10 @@ const statePath = "/var/lib/wesher/state.json"
 func newCluster(config *config, wg *wgState) (*cluster, error) {
 	clusterKey := config.ClusterKey
 
-	state := loadState()
+	state := &ClusterState{}
+	if !config.Init {
+		loadState(state)
+	}
 	if len(clusterKey) == 0 {
 		clusterKey = state.ClusterKey
 	}
@@ -223,19 +226,21 @@ func (c *cluster) saveState() error {
 	return ioutil.WriteFile(statePath, stateOut, 0700)
 }
 
-func loadState() *ClusterState {
+func loadState(cs *ClusterState) {
 	content, err := ioutil.ReadFile(statePath)
 	if err != nil {
 		if !os.IsNotExist(err) {
 			logrus.Warnf("could not open state in %s: %s", statePath, err)
 		}
-		return &ClusterState{}
+		return
 	}
 
-	s := &ClusterState{}
-	if err := json.Unmarshal(content, s); err != nil {
+	// avoid partially unmarshalled content by using a temp var
+	csTmp := &ClusterState{}
+	if err := json.Unmarshal(content, csTmp); err != nil {
 		logrus.Warnf("could not decode state: %s", err)
-		return &ClusterState{} // avoid partially unmarshalled content
+	} else {
+		*cs = *csTmp
 	}
-	return s
+	return
 }