config: move NodeName validation to config validation

Previsouly it was done in Agent.Start, which is much later then it needs to be.

The new 'dns' package was required, because otherwise there would be an
import cycle. In the future we should move more of the dns server into
the dns package.

agent/agent.go

@@ -17,6 +17,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/hashicorp/consul/agent/dns"
 	"github.com/hashicorp/go-connlimit"
 	"github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/go-memdb"
@@ -642,21 +643,6 @@ func (a *Agent) Start(ctx context.Context) error {
 		return err
 	}
 
-	// Warn if the node name is incompatible with DNS
-	if InvalidDnsRe.MatchString(a.config.NodeName) {
-		a.logger.Warn("Node name will not be discoverable "+
-			"via DNS due to invalid characters. Valid characters include "+
-			"all alpha-numerics and dashes.",
-			"node_name", a.config.NodeName,
-		)
-	} else if len(a.config.NodeName) > MaxDNSLabelLength {
-		a.logger.Warn("Node name will not be discoverable "+
-			"via DNS due to it being too long. Valid lengths are between "+
-			"1 and 63 bytes.",
-			"node_name", a.config.NodeName,
-		)
-	}
-
 	// load the tokens - this requires the logger to be setup
 	// which is why we can't do this in New
 	a.loadTokens(a.config)
@@ -2484,13 +2470,13 @@ func (a *Agent) validateService(service *structs.NodeService, chkTypes []*struct
 	}
 
 	// Warn if the service name is incompatible with DNS
-	if InvalidDnsRe.MatchString(service.Service) {
+	if dns.InvalidNameRe.MatchString(service.Service) {
 		a.logger.Warn("Service name will not be discoverable "+
 			"via DNS due to invalid characters. Valid characters include "+
 			"all alpha-numerics and dashes.",
 			"service", service.Service,
 		)
-	} else if len(service.Service) > MaxDNSLabelLength {
+	} else if len(service.Service) > dns.MaxLabelLength {
 		a.logger.Warn("Service name will not be discoverable "+
 			"via DNS due to it being too long. Valid lengths are between "+
 			"1 and 63 bytes.",
@@ -2500,13 +2486,13 @@ func (a *Agent) validateService(service *structs.NodeService, chkTypes []*struct
 
 	// Warn if any tags are incompatible with DNS
 	for _, tag := range service.Tags {
-		if InvalidDnsRe.MatchString(tag) {
+		if dns.InvalidNameRe.MatchString(tag) {
 			a.logger.Debug("Service tag will not be discoverable "+
 				"via DNS due to invalid characters. Valid characters include "+
 				"all alpha-numerics and dashes.",
 				"tag", tag,
 			)
-		} else if len(tag) > MaxDNSLabelLength {
+		} else if len(tag) > dns.MaxLabelLength {
 			a.logger.Debug("Service tag will not be discoverable "+
 				"via DNS due to it being too long. Valid lengths are between "+
 				"1 and 63 bytes.",

agent/config/builder.go

@@ -19,6 +19,7 @@ import (
 	"github.com/hashicorp/consul/agent/connect/ca"
 	"github.com/hashicorp/consul/agent/consul"
 	"github.com/hashicorp/consul/agent/consul/authmethod/ssoauth"
+	"github.com/hashicorp/consul/agent/dns"
 	"github.com/hashicorp/consul/agent/structs"
 	"github.com/hashicorp/consul/ipaddr"
 	"github.com/hashicorp/consul/lib"
@@ -1117,9 +1118,20 @@ func (b *Builder) Validate(rt RuntimeConfig) error {
 			return fmt.Errorf("data_dir %q is not a directory", rt.DataDir)
 		}
 	}
-	if rt.NodeName == "" {
+
+	switch {
+	case rt.NodeName == "":
 		return fmt.Errorf("node_name cannot be empty")
+	case dns.InvalidNameRe.MatchString(rt.NodeName):
+		b.warn("Node name %q will not be discoverable "+
+			"via DNS due to invalid characters. Valid characters include "+
+			"all alpha-numerics and dashes.", rt.NodeName)
+	case len(rt.NodeName) > dns.MaxLabelLength:
+		b.warn("Node name %q will not be discoverable "+
+			"via DNS due to it being too long. Valid lengths are between "+
+			"1 and 63 bytes.", rt.NodeName)
 	}
+
 	if ipaddr.IsAny(rt.AdvertiseAddrLAN.IP) {
 		return fmt.Errorf("Advertise address cannot be 0.0.0.0, :: or [::]")
 	}

agent/config/builder_test.go

@@ -3,8 +3,10 @@ package config
 import (
 	"fmt"
 	"io/ioutil"
+	"net"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -121,3 +123,62 @@ func setupConfigFiles(t *testing.T) []string {
 		subpath,
 	}
 }
+
+func TestBuilder_BuildAndValidate_NodeName(t *testing.T) {
+	type testCase struct {
+		name         string
+		nodeName     string
+		expectedWarn string
+	}
+
+	fn := func(t *testing.T, tc testCase) {
+		b, err := NewBuilder(BuilderOpts{
+			Config: Config{
+				NodeName: pString(tc.nodeName),
+				DataDir:  pString("dir"),
+			},
+		})
+		patchBuilderShims(b)
+		require.NoError(t, err)
+		_, err = b.BuildAndValidate()
+		require.NoError(t, err)
+		require.Len(t, b.Warnings, 1)
+		require.Contains(t, b.Warnings[0], tc.expectedWarn)
+	}
+
+	var testCases = []testCase{
+		{
+			name:         "invalid character - unicode",
+			nodeName:     "🐼",
+			expectedWarn: `Node name "🐼" will not be discoverable via DNS due to invalid characters`,
+		},
+		{
+			name:         "invalid character - slash",
+			nodeName:     "thing/other/ok",
+			expectedWarn: `Node name "thing/other/ok" will not be discoverable via DNS due to invalid characters`,
+		},
+		{
+			name:         "too long",
+			nodeName:     strings.Repeat("a", 66),
+			expectedWarn: "due to it being too long.",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			fn(t, tc)
+		})
+	}
+}
+
+func patchBuilderShims(b *Builder) {
+	b.hostname = func() (string, error) {
+		return "thehostname", nil
+	}
+	b.getPrivateIPv4 = func() ([]*net.IPAddr, error) {
+		return []*net.IPAddr{ipAddr("10.0.0.1")}, nil
+	}
+	b.getPublicIPv6 = func() ([]*net.IPAddr, error) {
+		return []*net.IPAddr{ipAddr("dead:beef::1")}, nil
+	}
+}

agent/config/runtime_test.go

@@ -4280,27 +4280,16 @@ func testConfig(t *testing.T, tests []configTest, dataDir string) {
 					t.Fatal("NewBuilder", err)
 				}
 
-				// mock the hostname function unless a mock is provided
+				patchBuilderShims(b)
+				if tt.hostname != nil {
 					b.hostname = tt.hostname
-				if b.hostname == nil {
-					b.hostname = func() (string, error) { return "nodex", nil }
 				}
-
-				// mock the ip address detection
-				privatev4 := tt.privatev4
-				if privatev4 == nil {
-					privatev4 = func() ([]*net.IPAddr, error) {
-						return []*net.IPAddr{ipAddr("10.0.0.1")}, nil
+				if tt.privatev4 != nil {
+					b.getPrivateIPv4 = tt.privatev4
 				}
+				if tt.publicv6 != nil {
+					b.getPublicIPv6 = tt.publicv6
 				}
-				publicv6 := tt.publicv6
-				if publicv6 == nil {
-					publicv6 = func() ([]*net.IPAddr, error) {
-						return []*net.IPAddr{ipAddr("dead:beef::1")}, nil
-					}
-				}
-				b.getPrivateIPv4 = privatev4
-				b.getPublicIPv6 = publicv6
 
 				// read the source fragements
 				for i, data := range srcs {
@@ -4332,12 +4321,10 @@ func testConfig(t *testing.T, tests []configTest, dataDir string) {
 				if err != nil && tt.err != "" && !strings.Contains(err.Error(), tt.err) {
 					t.Fatalf("error %q does not contain %q", err.Error(), tt.err)
 				}
-				require.Equal(t, tt.warns, b.Warnings, "warnings")
-
-				// stop if we expected an error
 				if tt.err != "" {
 					return
 				}
+				require.Equal(t, tt.warns, b.Warnings, "warnings")
 
 				// build a default configuration, then patch the fields we expect to change
 				// and compare it with the generated configuration. Since the expected

agent/dns.go

@@ -5,17 +5,17 @@ import (
 	"encoding/hex"
 	"fmt"
 	"net"
+	"regexp"
 	"strings"
 	"sync/atomic"
 	"time"
 
-	"regexp"
-
 	metrics "github.com/armon/go-metrics"
 	radix "github.com/armon/go-radix"
 	"github.com/coredns/coredns/plugin/pkg/dnsutil"
 	cachetype "github.com/hashicorp/consul/agent/cache-types"
 	"github.com/hashicorp/consul/agent/config"
+	agentdns "github.com/hashicorp/consul/agent/dns"
 	"github.com/hashicorp/consul/agent/structs"
 	"github.com/hashicorp/consul/api"
 	"github.com/hashicorp/consul/ipaddr"
@@ -38,12 +38,8 @@ const (
 	staleCounterThreshold = 5 * time.Second
 
 	defaultMaxUDPSize = 512
-
-	MaxDNSLabelLength = 63
 )
 
-var InvalidDnsRe = regexp.MustCompile(`[^A-Za-z0-9\\-]+`)
-
 type dnsSOAConfig struct {
 	Refresh uint32 // 3600 by default
 	Retry   uint32 // 600
@@ -539,7 +535,7 @@ func (d *DNSServer) nameservers(cfg *dnsConfig, maxRecursionLevel int) (ns []dns
 	for _, o := range out.Nodes {
 		name, dc := o.Node.Node, o.Node.Datacenter
 
-		if InvalidDnsRe.MatchString(name) {
+		if agentdns.InvalidNameRe.MatchString(name) {
 			d.logger.Warn("Skipping invalid node for NS records", "node", name)
 			continue
 		}

agent/dns/dns.go

@@ -0,0 +1,10 @@
+package dns
+
+import "regexp"
+
+// MaxLabelLength is the maximum length for a name that can be used in DNS.
+const MaxLabelLength = 63
+
+// InvalidNameRe is a regex that matches characters which can not be included in
+// a DNS name.
+var InvalidNameRe = regexp.MustCompile(`[^A-Za-z0-9\\-]+`)

agent/dns_test.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/hashicorp/consul/agent/config"
+	agentdns "github.com/hashicorp/consul/agent/dns"
 	"github.com/hashicorp/consul/agent/structs"
 	"github.com/hashicorp/consul/api"
 	"github.com/hashicorp/consul/lib"
@@ -6976,7 +6977,7 @@ func TestDNSInvalidRegex(t *testing.T) {
 	}
 	for _, test := range tests {
 		t.Run(test.desc, func(t *testing.T) {
-			if got, want := InvalidDnsRe.MatchString(test.in), test.invalid; got != want {
+			if got, want := agentdns.InvalidNameRe.MatchString(test.in), test.invalid; got != want {
 				t.Fatalf("Expected %v to return %v", test.in, want)
 			}
 		})