Adding DNS based node lookup

command/agent/catalog_endpoint.go

@@ -144,8 +144,8 @@ func (s *HTTPServer) CatalogNodeServices(resp http.ResponseWriter, req *http.Req
 	}
 
 	// Make the RPC request
-	var out structs.NodeServices
-	if err := s.agent.RPC("Catalog.NodeServices", &args, &out); err != nil {
+	out := new(structs.NodeServices)
+	if err := s.agent.RPC("Catalog.NodeServices", &args, out); err != nil {
 		return nil, err
 	}
 	return out, nil

command/agent/catalog_endpoint_test.go

@@ -232,8 +232,8 @@ func TestCatalogNodeServices(t *testing.T) {
 		t.Fatalf("err: %v", err)
 	}
 
-	services := obj.(structs.NodeServices)
-	if len(services) != 1 {
+	services := obj.(*structs.NodeServices)
+	if len(services.Services) != 1 {
 		t.Fatalf("bad: %v", obj)
 	}
 }

command/agent/dns.go

@@ -2,23 +2,35 @@ package agent
 
 import (
 	"fmt"
+	"github.com/hashicorp/consul/consul/structs"
 	"github.com/miekg/dns"
 	"io"
 	"log"
+	"net"
+	"strings"
 	"time"
 )
 
+const (
+	testQuery    = "_test.consul."
+	consulDomain = "consul."
+)
+
 // DNSServer is used to wrap an Agent and expose various
 // service discovery endpoints using a DNS interface.
 type DNSServer struct {
 	agent      *Agent
 	dnsHandler *dns.ServeMux
 	dnsServer  *dns.Server
+	domain     string
 	logger     *log.Logger
 }
 
 // NewDNSServer starts a new DNS server to provide an agent interface
 func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSServer, error) {
+	// Make sure domain is FQDN
+	domain = dns.Fqdn(domain)
+
 	// Construct the DNS components
 	mux := dns.NewServeMux()
 
@@ -35,11 +47,15 @@ func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSS
 		agent:      agent,
 		dnsHandler: mux,
 		dnsServer:  server,
+		domain:     domain,
 		logger:     log.New(logOutput, "", log.LstdFlags),
 	}
 
-	// Register mux handlers
-	mux.HandleFunc("consul.", srv.handleConsul)
+	// Register mux handlers, always handle "consul."
+	mux.HandleFunc(domain, srv.handleQuery)
+	if domain != consulDomain {
+		mux.HandleFunc(consulDomain, srv.handleTest)
+	}
 
 	// Async start the DNS Server, handle a potential error
 	errCh := make(chan error, 1)
@@ -57,7 +73,7 @@ func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSS
 		time.Sleep(50 * time.Millisecond)
 
 		m := new(dns.Msg)
-		m.SetQuestion("_test.consul.", dns.TypeANY)
+		m.SetQuestion(testQuery, dns.TypeANY)
 
 		c := new(dns.Client)
 		in, _, err := c.Exchange(m, bind)
@@ -85,12 +101,41 @@ func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSS
 	return srv, nil
 }
 
-// handleConsul is used to handle DNS queries in the ".consul." domain
-func (d *DNSServer) handleConsul(resp dns.ResponseWriter, req *dns.Msg) {
+// handleQUery is used to handle DNS queries in the configured domain
+func (d *DNSServer) handleQuery(resp dns.ResponseWriter, req *dns.Msg) {
+	q := req.Question[0]
+	defer func(s time.Time) {
+		d.logger.Printf("[DEBUG] dns: request for %v (%v)", q, time.Now().Sub(s))
+	}(time.Now())
+
+	// Check if this is potentially a test query
+	if q.Name == testQuery {
+		d.handleTest(resp, req)
+		return
+	}
+
+	// Setup the message response
+	m := new(dns.Msg)
+	m.SetReply(req)
+	m.Authoritative = true
+	d.addSOA(d.domain, m)
+	defer resp.WriteMsg(m)
+
+	// Dispatch the correct handler
+	d.dispatch(req, m)
+}
+
+// handleTest is used to handle DNS queries in the ".consul." domain
+func (d *DNSServer) handleTest(resp dns.ResponseWriter, req *dns.Msg) {
 	q := req.Question[0]
-	d.logger.Printf("[DEBUG] dns: request for %v", q)
+	defer func(s time.Time) {
+		d.logger.Printf("[DEBUG] dns: request for %v (%v)", q, time.Now().Sub(s))
+	}(time.Now())
 
-	if q.Qtype != dns.TypeANY && q.Qtype != dns.TypeTXT {
+	if !(q.Qtype == dns.TypeANY || q.Qtype == dns.TypeTXT) {
+		return
+	}
+	if q.Name != testQuery {
 		return
 	}
 
@@ -101,7 +146,7 @@ func (d *DNSServer) handleConsul(resp dns.ResponseWriter, req *dns.Msg) {
 	header := dns.RR_Header{Name: q.Name, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 0}
 	txt := &dns.TXT{header, []string{"ok"}}
 	m.Answer = append(m.Answer, txt)
-	d.addSOA("consul.", m)
+	d.addSOA(consulDomain, m)
 	resp.WriteMsg(m)
 }
 
@@ -124,3 +169,103 @@ func (d *DNSServer) addSOA(domain string, msg *dns.Msg) {
 	}
 	msg.Ns = append(msg.Ns, soa)
 }
+
+// dispatch is used to parse a request and invoke the correct handler
+func (d *DNSServer) dispatch(req, resp *dns.Msg) {
+	// By default the query is in the default datacenter
+	datacenter := d.agent.config.Datacenter
+
+	// Get the QName without the domain suffix
+	qName := dns.Fqdn(req.Question[0].Name)
+	qName = strings.TrimSuffix(qName, d.domain)
+
+	// Split into the label parts
+	labels := dns.SplitDomainName(qName)
+
+	// The last label is either "node", "service" or a datacenter name
+PARSE:
+	if len(labels) == 0 {
+		goto INVALID
+	}
+	switch labels[len(labels)-1] {
+	case "service":
+		// Handle lookup with and without tag
+		switch len(labels) {
+		case 2:
+			d.serviceLookup(datacenter, labels[0], "", req, resp)
+		case 3:
+			d.serviceLookup(datacenter, labels[1], labels[0], req, resp)
+		default:
+			goto INVALID
+		}
+
+	case "node":
+		if len(labels) != 2 {
+			goto INVALID
+		}
+		d.nodeLookup(datacenter, labels[0], req, resp)
+
+	default:
+		// Store the DC, and re-parse
+		datacenter = labels[len(labels)-1]
+		labels = labels[:len(labels)-1]
+		goto PARSE
+	}
+	return
+INVALID:
+	d.logger.Printf("[WARN] dns: QName invalid: %s", qName)
+	resp.SetRcode(req, dns.RcodeNameError)
+}
+
+// nodeLookup is used to handle a node query
+func (d *DNSServer) nodeLookup(datacenter, node string, req, resp *dns.Msg) {
+	// Only handle ANY and A type requests
+	qType := req.Question[0].Qtype
+	if qType != dns.TypeANY && qType != dns.TypeA {
+		return
+	}
+
+	// Make an RPC request
+	args := structs.NodeServicesRequest{
+		Datacenter: datacenter,
+		Node:       node,
+	}
+	var out structs.NodeServices
+	if err := d.agent.RPC("Catalog.NodeServices", &args, &out); err != nil {
+		d.logger.Printf("[ERR] dns: rpc error: %v", err)
+		resp.SetRcode(req, dns.RcodeServerFailure)
+		return
+	}
+
+	// If we have no address, return not found!
+	if out.Address == "" {
+		resp.SetRcode(req, dns.RcodeNameError)
+		return
+	}
+
+	// Parse the IP
+	ip := net.ParseIP(out.Address)
+	if ip == nil {
+		d.logger.Printf("[ERR] dns: failed to parse IP %v for %v", out.Address, node)
+		resp.SetRcode(req, dns.RcodeServerFailure)
+		return
+	}
+
+	// Format A record
+	aRec := &dns.A{
+		Hdr: dns.RR_Header{
+			Name:   req.Question[0].Name,
+			Rrtype: dns.TypeA,
+			Class:  dns.ClassINET,
+			Ttl:    0,
+		},
+		A: ip,
+	}
+
+	// Add the response
+	resp.Answer = append(resp.Answer, aRec)
+}
+
+// serviceLookup is used to handle a service query
+func (d *DNSServer) serviceLookup(datacenter, service, tag string, req, resp *dns.Msg) {
+}

command/agent/dns_test.go

@@ -1,9 +1,11 @@
 package agent
 
 import (
+	"github.com/hashicorp/consul/consul/structs"
 	"github.com/miekg/dns"
 	"os"
 	"testing"
+	"time"
 )
 
 func makeDNSServer(t *testing.T) (string, *DNSServer) {
@@ -42,3 +44,66 @@ func TestDNS_IsAlive(t *testing.T) {
 		t.Fatalf("Bad: %#v", in.Answer[0])
 	}
 }
+
+func TestDNS_NodeLookup(t *testing.T) {
+	dir, srv := makeDNSServer(t)
+	defer os.RemoveAll(dir)
+	defer srv.agent.Shutdown()
+
+	// Wait for leader
+	time.Sleep(100 * time.Millisecond)
+
+	// Register node
+	args := &structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+	}
+	var out struct{}
+	if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	m := new(dns.Msg)
+	m.SetQuestion("foo.node.consul.", dns.TypeANY)
+
+	c := new(dns.Client)
+	in, _, err := c.Exchange(m, srv.agent.config.DNSAddr)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if len(in.Answer) != 1 {
+		t.Fatalf("Bad: %#v", in)
+	}
+
+	aRec, ok := in.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatalf("Bad: %#v", in.Answer[0])
+	}
+	if aRec.A.String() != "127.0.0.1" {
+		t.Fatalf("Bad: %#v", in.Answer[0])
+	}
+
+	// Re-do the query, but specify the DC
+	m = new(dns.Msg)
+	m.SetQuestion("foo.node.dc1.consul.", dns.TypeANY)
+
+	c = new(dns.Client)
+	in, _, err = c.Exchange(m, srv.agent.config.DNSAddr)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if len(in.Answer) != 1 {
+		t.Fatalf("Bad: %#v", in)
+	}
+
+	aRec, ok = in.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatalf("Bad: %#v", in.Answer[0])
+	}
+	if aRec.A.String() != "127.0.0.1" {
+		t.Fatalf("Bad: %#v", in.Answer[0])
+	}
+}

command/agent/http.go

@@ -72,14 +72,14 @@ func (s *HTTPServer) wrap(handler func(resp http.ResponseWriter, req *http.Reque
 		// Invoke the handler
 		start := time.Now()
 		defer func() {
-			s.logger.Printf("[DEBUG] HTTP Request %v (%v)", req.URL, time.Now().Sub(start))
+			s.logger.Printf("[DEBUG] http: Request %v (%v)", req.URL, time.Now().Sub(start))
 		}()
 		obj, err := handler(resp, req)
 
 		// Check for an error
 	HAS_ERR:
 		if err != nil {
-			s.logger.Printf("[ERR] Request %v, error: %v", req.URL, err)
+			s.logger.Printf("[ERR] http: Request %v, error: %v", req.URL, err)
 			resp.WriteHeader(500)
 			resp.Write([]byte(err.Error()))
 			return