resolver: less debug

Observed lots of debug messages from resolver (and associated high CPU
usage because of lots of logging) when debug logging is turned on. Here
is some data from a real system:

> $ journalctl -u docker --since="2019-10-21 21:00:00"  --until="2019-10-21 22:00:00"  | wc -l
> 188621
> $ journalctl -u docker --since="2019-10-21 21:00:00"  --until="2019-10-21 22:00:00"  | grep -E 'Name To resolve: |\[resolver\] ' | wc -l
> 186319

So, it was about 200000 lines logger for just one hour, and about 99%
of that are from resolver. While this might be the peculiarity of
a particular setup, the number of such messages still seem way too
excessive.

Remove the ones that are not errors.

Signed-off-by: Kir Kolyshkin <[email protected]>

resolver.go

@@ -255,8 +255,6 @@ func (r *resolver) handleIPQuery(name string, query *dns.Msg, ipType int) (*dns.
 		return nil, nil
 	}
 
-	logrus.Debugf("[resolver] lookup for %s: IP %v", name, addr)
-
 	resp := createRespMsg(query)
 	if len(addr) > 1 {
 		addr = shuffleAddr(addr)
@@ -296,7 +294,6 @@ func (r *resolver) handlePTRQuery(ptr string, query *dns.Msg) (*dns.Msg, error)
 		return nil, nil
 	}
 
-	logrus.Debugf("[resolver] lookup for IP %s: name %s", parts[0], host)
 	fqdn := dns.Fqdn(host)
 
 	resp := new(dns.Msg)
@@ -452,9 +449,6 @@ func (r *resolver) ServeDNS(w dns.ResponseWriter, query *dns.Msg) {
 				logrus.Warnf("[resolver] connect failed: %s", err)
 				continue
 			}
-			queryType := dns.TypeToString[query.Question[0].Qtype]
-			logrus.Debugf("[resolver] query %s (%s) from %s, forwarding to %s:%s", name, queryType,
-				extConn.LocalAddr().String(), proto, extDNS.IPStr)
 
 			// Timeout has to be set for every IO operation.
 			extConn.SetDeadline(time.Now().Add(extIOTimeout))
@@ -522,18 +516,13 @@ func (r *resolver) ServeDNS(w dns.ResponseWriter, query *dns.Msg) {
 				case dns.TypeA:
 					answers++
 					ip := rr.(*dns.A).A
-					logrus.Debugf("[resolver] received A record %q for %q from %s:%s", ip, h.Name, proto, extDNS.IPStr)
 					r.backend.HandleQueryResp(h.Name, ip)
 				case dns.TypeAAAA:
 					answers++
 					ip := rr.(*dns.AAAA).AAAA
-					logrus.Debugf("[resolver] received AAAA record %q for %q from %s:%s", ip, h.Name, proto, extDNS.IPStr)
 					r.backend.HandleQueryResp(h.Name, ip)
 				}
 			}
-			if resp.Answer == nil || answers == 0 {
-				logrus.Debugf("[resolver] external DNS %s:%s did not return any %s records for %q", proto, extDNS.IPStr, queryType, name)
-			}
 			resp.Compress = true
 			break
 		}

sandbox.go

@@ -529,7 +529,6 @@ func (sb *sandbox) ResolveName(name string, ipType int) ([]net.IP, bool) {
 	// {a.b in network c.d},
 	// {a in network b.c.d},
 
-	logrus.Debugf("Name To resolve: %v", name)
 	name = strings.TrimSuffix(name, ".")
 	reqName := []string{name}
 	networkName := []string{""}