Add label-based dns

* Add ability to read swarmdns-names label to array

* Map name to node

* Answer nodes per name

* Add out for domain comp

* add dot to end of normDomain

* move dot to matchingDomain

* don't override nodes if no match in map

main.go

@@ -36,6 +36,7 @@ var client swarm.Client
 var logflag bool
 var rateLimit int64
 var nodes []swarm.SwarmNode
+var nameToNodeMap map[string][]swarm.SwarmNode
 var mutex = &sync.Mutex{}
 var swarmDomains arrayFlags
 var returnWorkers bool
@@ -142,9 +143,29 @@ func handleRequest(w dns.ResponseWriter, r *dns.Msg) {
 	w.WriteMsg(m)
 }
 
+func replaceLast(s, search, replace string) string {
+	i := strings.LastIndex(s, search)
+	if i == -1 {
+		return s
+	}
+	return s[:i] + replace + s[i+len(search):]
+}
+
 func answerForNodes(domain string) []dns.RR {
 	mutex.Lock()
 	var rrs []dns.RR
+	var nodes = nodes
+
+	var swarmDomain = *matchingDomain(domain) + "."
+	var normDomain = strings.ToLower(domain)
+
+	if swarmDomain != normDomain {
+		var subDomain = replaceLast(normDomain, "."+swarmDomain, "")
+		if len(nameToNodeMap[subDomain]) > 0 {
+			nodes = nameToNodeMap[subDomain]
+		}
+	}
+
 	for _, node := range nodes {
 		if node.IsManager || returnWorkers {
 			rr := new(dns.A)
@@ -172,9 +193,28 @@ func refreshNodes() {
 
 	mutex.Lock()
 	nodes, err = client.ListActiveNodes()
+	mapNodesToNames(nodes)
 	logger.Printf("Refreshed nodes: %v\n", nodes)
 	mutex.Unlock()
 	if err != nil {
 		panic(err)
 	}
 }
+
+func mapNodesToNames(nodes []swarm.SwarmNode) {
+	var newMap = make(map[string][]swarm.SwarmNode)
+
+	for _, node := range nodes {
+		if len(node.DnsNames) <= 0 {
+			continue
+		}
+
+		for _, name := range node.DnsNames {
+			newMap[name] = append(newMap[name], node)
+
+			logger.Printf("Mapped: [%v] to [%v]\n", node.Hostname, name)
+		}
+	}
+
+	nameToNodeMap = newMap
+}

swarm/client.go

@@ -13,6 +13,7 @@ type SwarmNode struct {
 	Ip        string
 	Hostname  string
 	IsManager bool
+	DnsNames  []string
 }
 
 type Client interface {
@@ -54,7 +55,13 @@ func (client swarmClient) ListActiveNodes() ([]SwarmNode, error) {
 				ip = node.Status.Addr
 			}
 
-			nodes = append(nodes, SwarmNode{Ip: ip, Hostname: getHostname(node), IsManager: node.ManagerStatus != nil})
+			nodes = append(nodes,
+				SwarmNode{
+					Ip:        ip,
+					Hostname:  getHostname(node),
+					IsManager: node.ManagerStatus != nil,
+					DnsNames:  getDnsNames(node),
+				})
 		}
 	}
 
@@ -73,3 +80,20 @@ func getIPFromAddr(addr string) string {
 	ipAndPort := strings.Split(addr, ":")
 	return ipAndPort[0]
 }
+
+func getDnsNames(node swarm.Node) []string {
+	var namesStr = node.Spec.Annotations.Labels["swarmdns-names"]
+
+	if len(namesStr) <= 0 {
+		return []string{}
+	}
+
+	var names = strings.Split(namesStr, ",")
+
+	// Just to trim whitespaces
+	for i, name := range names {
+		names[i] = strings.Trim(name, " ")
+	}
+
+	return names
+}