Update DNS

Author: arjunkomath

agent/internal/container/runtime_linux.go

@@ -12,7 +12,6 @@ import (
 	"strings"
 	"time"
 
-	"techulus/cloud-agent/internal/dns"
 	"techulus/cloud-agent/internal/retry"
 )
 
@@ -122,9 +121,6 @@ func Deploy(config *DeployConfig) (*DeployResult, error) {
 		}
 	}
 
-	if dnsIP := dns.GetContainerDNS(); dnsIP != "" {
-		args = append(args, "--dns", dnsIP)
-	}
 
 	if config.HealthCheck != nil && config.HealthCheck.Cmd != "" {
 		args = append(args, "--health-cmd", config.HealthCheck.Cmd)
@@ -516,7 +512,6 @@ func EnsureNetwork(subnetId int) error {
 		"--driver", "bridge",
 		"--subnet", subnet,
 		"--gateway", gateway,
-		"--disable-dns",
 		NetworkName,
 	}
 

agent/internal/dns/handler.go

@@ -1,31 +1,13 @@
 package dns
 
 import (
-	"time"
-
 	"github.com/miekg/dns"
 )
 
 const defaultTTL = 30
 
-var upstreamServers = []string{
-	"8.8.8.8:53",
-	"1.1.1.1:53",
-}
-
 type dnsHandler struct {
-	store  *RecordStore
-	client *dns.Client
-}
-
-func newDNSHandler(store *RecordStore) *dnsHandler {
-	return &dnsHandler{
-		store: store,
-		client: &dns.Client{
-			Net:     "udp",
-			Timeout: 5 * time.Second,
-		},
-	}
+	store *RecordStore
 }
 
 func (h *dnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
@@ -36,29 +18,23 @@ func (h *dnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 	for _, q := range r.Question {
 		switch q.Qtype {
 		case dns.TypeA:
-			if !h.handleA(m, q) {
-				h.forwardQuery(w, r)
-				return
-			}
+			h.handleA(m, q)
 		case dns.TypeAAAA:
-			if !h.handleAAAA(m, q) {
-				h.forwardQuery(w, r)
-				return
-			}
+			h.handleAAAA(m, q)
 		default:
-			h.forwardQuery(w, r)
-			return
+			m.Rcode = dns.RcodeNotImplemented
 		}
 	}
 
 	w.WriteMsg(m)
 }
 
-func (h *dnsHandler) handleA(m *dns.Msg, q dns.Question) bool {
+func (h *dnsHandler) handleA(m *dns.Msg, q dns.Question) {
 	ips := h.store.Lookup(q.Name)
 
 	if ips == nil {
-		return false
+		m.Rcode = dns.RcodeNameError
+		return
 	}
 
 	for _, ip := range ips {
@@ -75,14 +51,14 @@ func (h *dnsHandler) handleA(m *dns.Msg, q dns.Question) bool {
 			m.Answer = append(m.Answer, rr)
 		}
 	}
-	return true
 }
 
-func (h *dnsHandler) handleAAAA(m *dns.Msg, q dns.Question) bool {
+func (h *dnsHandler) handleAAAA(m *dns.Msg, q dns.Question) {
 	ips := h.store.Lookup(q.Name)
 
 	if ips == nil {
-		return false
+		m.Rcode = dns.RcodeNameError
+		return
 	}
 
 	for _, ip := range ips {
@@ -99,22 +75,4 @@ func (h *dnsHandler) handleAAAA(m *dns.Msg, q dns.Question) bool {
 			m.Answer = append(m.Answer, rr)
 		}
 	}
-	return true
-}
-
-func (h *dnsHandler) forwardQuery(w dns.ResponseWriter, r *dns.Msg) {
-	for _, server := range upstreamServers {
-		resp, _, err := h.client.Exchange(r, server)
-		if err != nil {
-			continue
-		}
-		resp.Id = r.Id
-		w.WriteMsg(resp)
-		return
-	}
-
-	m := new(dns.Msg)
-	m.SetReply(r)
-	m.Rcode = dns.RcodeServerFailure
-	w.WriteMsg(m)
 }

agent/internal/dns/server.go

@@ -42,7 +42,7 @@ func (s *Server) Start(ctx context.Context) error {
 
 	addr := fmt.Sprintf("%s:%d", s.listenAddr, s.port)
 
-	handler := newDNSHandler(s.store)
+	handler := &dnsHandler{store: s.store}
 
 	udpReady := make(chan struct{})
 	tcpReady := make(chan struct{})