Add support for MX records in Azure, GCP and AWS

endpoint/endpoint.go

@@ -40,6 +40,8 @@ const (
 	RecordTypeNS = "NS"
 	// RecordTypePTR is a RecordType enum value
 	RecordTypePTR = "PTR"
+	// RecordTypeMX is a RecordType enum value
+	RecordTypeMX = "MX"
 )
 
 // TTL is a structure defining the TTL of a DNS record

provider/aws/aws.go

@@ -373,7 +373,7 @@ func (p *AWSProvider) records(ctx context.Context, zones map[string]*route53.Hos
 		for _, r := range resp.ResourceRecordSets {
 			newEndpoints := make([]*endpoint.Endpoint, 0)
 
-			if !provider.SupportedRecordType(aws.StringValue(r.Type)) {
+			if !p.SupportedRecordType(aws.StringValue(r.Type)) {
 				continue
 			}
 
@@ -1059,3 +1059,12 @@ func canonicalHostedZone(hostname string) string {
 func cleanZoneID(id string) string {
 	return strings.TrimPrefix(id, "/hostedzone/")
 }
+
+func (p *AWSProvider) SupportedRecordType(recordType string) bool {
+	switch recordType {
+	case "MX":
+		return true
+	default:
+		return provider.SupportedRecordType(recordType)
+	}
+}

provider/azure/azure.go

@@ -109,7 +109,7 @@ func (p *AzureProvider) Records(ctx context.Context) (endpoints []*endpoint.Endp
 				return true
 			}
 			recordType := strings.TrimPrefix(*recordSet.Type, "Microsoft.Network/dnszones/")
-			if !provider.SupportedRecordType(recordType) {
+			if !p.SupportedRecordType(recordType) {
 				return true
 			}
 			name := formatAzureDNSName(*recordSet.Name, *zone.Name)
@@ -190,6 +190,15 @@ func (p *AzureProvider) zones(ctx context.Context) ([]dns.Zone, error) {
 	return zones, nil
 }
 
+func (p *AzureProvider) SupportedRecordType(recordType string) bool {
+	switch recordType {
+	case "MX":
+		return true
+	default:
+		return provider.SupportedRecordType(recordType)
+	}
+}
+
 func (p *AzureProvider) iterateRecords(ctx context.Context, zoneName string, callback func(dns.RecordSet) bool) error {
 	log.Debugf("Retrieving Azure DNS records for zone '%s'.", zoneName)
 
@@ -377,6 +386,21 @@ func (p *AzureProvider) newRecordSet(endpoint *endpoint.Endpoint) (dns.RecordSet
 				},
 			},
 		}, nil
+	case dns.MX:
+		mxRecords := make([]dns.MxRecord, len(endpoint.Targets))
+		for i, target := range endpoint.Targets {
+			mxRecord, err := parseMxTarget[dns.MxRecord](target)
+			if err != nil {
+				return dns.RecordSet{}, err
+			}
+			mxRecords[i] = mxRecord
+		}
+		return dns.RecordSet{
+			RecordSetProperties: &dns.RecordSetProperties{
+				TTL:       to.Int64Ptr(ttl),
+				MxRecords: &mxRecords,
+			},
+		}, nil
 	case dns.TXT:
 		return dns.RecordSet{
 			RecordSetProperties: &dns.RecordSetProperties{
@@ -425,6 +449,16 @@ func extractAzureTargets(recordSet *dns.RecordSet) []string {
 		return []string{*cnameRecord.Cname}
 	}
 
+	// Check for MX records
+	mxRecords := properties.MxRecords
+	if mxRecords != nil && len(*mxRecords) > 0 && (*mxRecords)[0].Exchange != nil {
+		targets := make([]string, len(*mxRecords))
+		for i, mxRecord := range *mxRecords {
+			targets[i] = fmt.Sprintf("%d %s", *mxRecord.Preference, *mxRecord.Exchange)
+		}
+		return targets
+	}
+
 	// Check for TXT records
 	txtRecords := properties.TxtRecords
 	if txtRecords != nil && len(*txtRecords) > 0 && (*txtRecords)[0].Value != nil {

provider/azure/azure_private_dns.go

@@ -367,6 +367,21 @@ func (p *AzurePrivateDNSProvider) newRecordSet(endpoint *endpoint.Endpoint) (pri
 				},
 			},
 		}, nil
+	case privatedns.MX:
+		mxRecords := make([]privatedns.MxRecord, len(endpoint.Targets))
+		for i, target := range endpoint.Targets {
+			mxRecord, err := parseMxTarget[privatedns.MxRecord](target)
+			if err != nil {
+				return privatedns.RecordSet{}, err
+			}
+			mxRecords[i] = mxRecord
+		}
+		return privatedns.RecordSet{
+			RecordSetProperties: &privatedns.RecordSetProperties{
+				TTL:       to.Int64Ptr(ttl),
+				MxRecords: &mxRecords,
+			},
+		}, nil
 	case privatedns.TXT:
 		return privatedns.RecordSet{
 			RecordSetProperties: &privatedns.RecordSetProperties{
@@ -407,6 +422,16 @@ func extractAzurePrivateDNSTargets(recordSet *privatedns.RecordSet) []string {
 		return []string{*cnameRecord.Cname}
 	}
 
+	// Check for MX records
+	mxRecords := properties.MxRecords
+	if mxRecords != nil && len(*mxRecords) > 0 && (*mxRecords)[0].Exchange != nil {
+		targets := make([]string, len(*mxRecords))
+		for i, mxRecord := range *mxRecords {
+			targets[i] = fmt.Sprintf("%d %s", *mxRecord.Preference, *mxRecord.Exchange)
+		}
+		return targets
+	}
+
 	// Check for TXT records
 	txtRecords := properties.TxtRecords
 	if txtRecords != nil && len(*txtRecords) > 0 && (*txtRecords)[0].Value != nil {

provider/azure/azure_privatedns_test.go

@@ -123,6 +123,17 @@ func privateCNameRecordSetPropertiesGetter(values []string, ttl int64) *privated
 	}
 }
 
+func privateMXRecordSetPropertiesGetter(values []string, ttl int64) *privatedns.RecordSetProperties {
+	mxRecords := make([]privatedns.MxRecord, len(values))
+	for i, target := range values {
+		mxRecords[i], _ = parseMxTarget[privatedns.MxRecord](target)
+	}
+	return &privatedns.RecordSetProperties{
+		TTL:       to.Int64Ptr(ttl),
+		MxRecords: &mxRecords,
+	}
+}
+
 func privateTxtRecordSetPropertiesGetter(values []string, ttl int64) *privatedns.RecordSetProperties {
 	return &privatedns.RecordSetProperties{
 		TTL: to.Int64Ptr(ttl),
@@ -156,6 +167,8 @@ func createPrivateMockRecordSetMultiWithTTL(name, recordType string, ttl int64,
 		getterFunc = privateARecordSetPropertiesGetter
 	case endpoint.RecordTypeCNAME:
 		getterFunc = privateCNameRecordSetPropertiesGetter
+	case endpoint.RecordTypeMX:
+		getterFunc = privateMXRecordSetPropertiesGetter
 	case endpoint.RecordTypeTXT:
 		getterFunc = privateTxtRecordSetPropertiesGetter
 	default:
@@ -266,6 +279,7 @@ func TestAzurePrivateDNSRecord(t *testing.T) {
 			createPrivateMockRecordSetWithTTL("nginx", endpoint.RecordTypeA, "123.123.123.123", 3600),
 			createPrivateMockRecordSetWithTTL("nginx", endpoint.RecordTypeTXT, "heritage=external-dns,external-dns/owner=default", recordTTL),
 			createPrivateMockRecordSetWithTTL("hack", endpoint.RecordTypeCNAME, "hack.azurewebsites.net", 10),
+			createPrivateMockRecordSetWithTTL("mail", endpoint.RecordTypeMX, "10 example.com", 4000),
 		})
 	if err != nil {
 		t.Fatal(err)
@@ -281,6 +295,7 @@ func TestAzurePrivateDNSRecord(t *testing.T) {
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeA, 3600, "123.123.123.123"),
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeTXT, recordTTL, "heritage=external-dns,external-dns/owner=default"),
 		endpoint.NewEndpointWithTTL("hack.example.com", endpoint.RecordTypeCNAME, 10, "hack.azurewebsites.net"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, 4000, "10 example.com"),
 	}
 
 	validateAzureEndpoints(t, actual, expected)
@@ -299,6 +314,7 @@ func TestAzurePrivateDNSMultiRecord(t *testing.T) {
 			createPrivateMockRecordSetMultiWithTTL("nginx", endpoint.RecordTypeA, 3600, "123.123.123.123", "234.234.234.234"),
 			createPrivateMockRecordSetWithTTL("nginx", endpoint.RecordTypeTXT, "heritage=external-dns,external-dns/owner=default", recordTTL),
 			createPrivateMockRecordSetWithTTL("hack", endpoint.RecordTypeCNAME, "hack.azurewebsites.net", 10),
+			createPrivateMockRecordSetMultiWithTTL("mail", endpoint.RecordTypeMX, 4000, "10 example.com", "20 backup.example.com"),
 		})
 	if err != nil {
 		t.Fatal(err)
@@ -314,6 +330,7 @@ func TestAzurePrivateDNSMultiRecord(t *testing.T) {
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeA, 3600, "123.123.123.123", "234.234.234.234"),
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeTXT, recordTTL, "heritage=external-dns,external-dns/owner=default"),
 		endpoint.NewEndpointWithTTL("hack.example.com", endpoint.RecordTypeCNAME, 10, "hack.azurewebsites.net"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, 4000, "10 example.com", "20 backup.example.com"),
 	}
 
 	validateAzureEndpoints(t, actual, expected)
@@ -329,6 +346,7 @@ func TestAzurePrivateDNSApplyChanges(t *testing.T) {
 		endpoint.NewEndpoint("oldcname.example.com", endpoint.RecordTypeCNAME, ""),
 		endpoint.NewEndpoint("deleted.example.com", endpoint.RecordTypeA, ""),
 		endpoint.NewEndpoint("deletedcname.example.com", endpoint.RecordTypeCNAME, ""),
+		endpoint.NewEndpoint("oldmail.example.com", endpoint.RecordTypeMX, ""),
 	})
 
 	validateAzureEndpoints(t, recordsClient.updatedEndpoints, []*endpoint.Endpoint{
@@ -342,6 +360,9 @@ func TestAzurePrivateDNSApplyChanges(t *testing.T) {
 		endpoint.NewEndpointWithTTL("other.com", endpoint.RecordTypeTXT, endpoint.TTL(recordTTL), "tag"),
 		endpoint.NewEndpointWithTTL("new.example.com", endpoint.RecordTypeA, 3600, "111.222.111.222"),
 		endpoint.NewEndpointWithTTL("newcname.example.com", endpoint.RecordTypeCNAME, 10, "other.com"),
+		endpoint.NewEndpointWithTTL("newmail.example.com", endpoint.RecordTypeMX, 7200, "40 bar.other.com"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(recordTTL), "10 other.com"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeTXT, endpoint.TTL(recordTTL), "tag"),
 	})
 }
 
@@ -401,17 +422,21 @@ func testAzurePrivateDNSApplyChangesInternal(t *testing.T, dryRun bool, client P
 		endpoint.NewEndpoint("other.com", endpoint.RecordTypeTXT, "tag"),
 		endpoint.NewEndpoint("nope.com", endpoint.RecordTypeA, "4.4.4.4"),
 		endpoint.NewEndpoint("nope.com", endpoint.RecordTypeTXT, "tag"),
+		endpoint.NewEndpoint("mail.example.com", endpoint.RecordTypeMX, "10 other.com"),
+		endpoint.NewEndpoint("mail.example.com", endpoint.RecordTypeTXT, "tag"),
 	}
 
 	currentRecords := []*endpoint.Endpoint{
 		endpoint.NewEndpoint("old.example.com", endpoint.RecordTypeA, "121.212.121.212"),
 		endpoint.NewEndpoint("oldcname.example.com", endpoint.RecordTypeCNAME, "other.com"),
 		endpoint.NewEndpoint("old.nope.com", endpoint.RecordTypeA, "121.212.121.212"),
+		endpoint.NewEndpoint("oldmail.example.com", endpoint.RecordTypeMX, "20 foo.other.com"),
 	}
 	updatedRecords := []*endpoint.Endpoint{
 		endpoint.NewEndpointWithTTL("new.example.com", endpoint.RecordTypeA, 3600, "111.222.111.222"),
 		endpoint.NewEndpointWithTTL("newcname.example.com", endpoint.RecordTypeCNAME, 10, "other.com"),
 		endpoint.NewEndpoint("new.nope.com", endpoint.RecordTypeA, "222.111.222.111"),
+		endpoint.NewEndpointWithTTL("newmail.example.com", endpoint.RecordTypeMX, 7200, "40 bar.other.com"),
 	}
 
 	deleteRecords := []*endpoint.Endpoint{

provider/azure/azure_test.go

@@ -122,6 +122,17 @@ func cNameRecordSetPropertiesGetter(values []string, ttl int64) *dns.RecordSetPr
 	}
 }
 
+func mxRecordSetPropertiesGetter(values []string, ttl int64) *dns.RecordSetProperties {
+	mxRecords := make([]dns.MxRecord, len(values))
+	for i, target := range values {
+		mxRecords[i], _ = parseMxTarget[dns.MxRecord](target)
+	}
+	return &dns.RecordSetProperties{
+		TTL:       to.Int64Ptr(ttl),
+		MxRecords: &mxRecords,
+	}
+}
+
 func txtRecordSetPropertiesGetter(values []string, ttl int64) *dns.RecordSetProperties {
 	return &dns.RecordSetProperties{
 		TTL: to.Int64Ptr(ttl),
@@ -155,6 +166,8 @@ func createMockRecordSetMultiWithTTL(name, recordType string, ttl int64, values
 		getterFunc = aRecordSetPropertiesGetter
 	case endpoint.RecordTypeCNAME:
 		getterFunc = cNameRecordSetPropertiesGetter
+	case endpoint.RecordTypeMX:
+		getterFunc = mxRecordSetPropertiesGetter
 	case endpoint.RecordTypeTXT:
 		getterFunc = txtRecordSetPropertiesGetter
 	default:
@@ -271,6 +284,7 @@ func TestAzureRecord(t *testing.T) {
 			createMockRecordSetWithTTL("nginx", endpoint.RecordTypeA, "123.123.123.123", 3600),
 			createMockRecordSetWithTTL("nginx", endpoint.RecordTypeTXT, "heritage=external-dns,external-dns/owner=default", recordTTL),
 			createMockRecordSetWithTTL("hack", endpoint.RecordTypeCNAME, "hack.azurewebsites.net", 10),
+			createMockRecordSetMultiWithTTL("mail", endpoint.RecordTypeMX, 4000, "10 example.com"),
 		})
 	if err != nil {
 		t.Fatal(err)
@@ -287,6 +301,7 @@ func TestAzureRecord(t *testing.T) {
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeA, 3600, "123.123.123.123"),
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeTXT, recordTTL, "heritage=external-dns,external-dns/owner=default"),
 		endpoint.NewEndpointWithTTL("hack.example.com", endpoint.RecordTypeCNAME, 10, "hack.azurewebsites.net"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, 4000, "10 example.com"),
 	}
 
 	validateAzureEndpoints(t, actual, expected)
@@ -305,6 +320,7 @@ func TestAzureMultiRecord(t *testing.T) {
 			createMockRecordSetMultiWithTTL("nginx", endpoint.RecordTypeA, 3600, "123.123.123.123", "234.234.234.234"),
 			createMockRecordSetWithTTL("nginx", endpoint.RecordTypeTXT, "heritage=external-dns,external-dns/owner=default", recordTTL),
 			createMockRecordSetWithTTL("hack", endpoint.RecordTypeCNAME, "hack.azurewebsites.net", 10),
+			createMockRecordSetMultiWithTTL("mail", endpoint.RecordTypeMX, 4000, "10 example.com", "20 backup.example.com"),
 		})
 	if err != nil {
 		t.Fatal(err)
@@ -321,6 +337,7 @@ func TestAzureMultiRecord(t *testing.T) {
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeA, 3600, "123.123.123.123", "234.234.234.234"),
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeTXT, recordTTL, "heritage=external-dns,external-dns/owner=default"),
 		endpoint.NewEndpointWithTTL("hack.example.com", endpoint.RecordTypeCNAME, 10, "hack.azurewebsites.net"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, 4000, "10 example.com", "20 backup.example.com"),
 	}
 
 	validateAzureEndpoints(t, actual, expected)
@@ -336,6 +353,7 @@ func TestAzureApplyChanges(t *testing.T) {
 		endpoint.NewEndpoint("oldcname.example.com", endpoint.RecordTypeCNAME, ""),
 		endpoint.NewEndpoint("deleted.example.com", endpoint.RecordTypeA, ""),
 		endpoint.NewEndpoint("deletedcname.example.com", endpoint.RecordTypeCNAME, ""),
+		endpoint.NewEndpoint("oldmail.example.com", endpoint.RecordTypeMX, ""),
 	})
 
 	validateAzureEndpoints(t, recordsClient.updatedEndpoints, []*endpoint.Endpoint{
@@ -349,6 +367,9 @@ func TestAzureApplyChanges(t *testing.T) {
 		endpoint.NewEndpointWithTTL("other.com", endpoint.RecordTypeTXT, endpoint.TTL(recordTTL), "tag"),
 		endpoint.NewEndpointWithTTL("new.example.com", endpoint.RecordTypeA, 3600, "111.222.111.222"),
 		endpoint.NewEndpointWithTTL("newcname.example.com", endpoint.RecordTypeCNAME, 10, "other.com"),
+		endpoint.NewEndpointWithTTL("newmail.example.com", endpoint.RecordTypeMX, 7200, "40 bar.other.com"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(recordTTL), "10 other.com"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeTXT, endpoint.TTL(recordTTL), "tag"),
 	})
 }
 
@@ -410,17 +431,21 @@ func testAzureApplyChangesInternal(t *testing.T, dryRun bool, client RecordSetsC
 		endpoint.NewEndpoint("other.com", endpoint.RecordTypeTXT, "tag"),
 		endpoint.NewEndpoint("nope.com", endpoint.RecordTypeA, "4.4.4.4"),
 		endpoint.NewEndpoint("nope.com", endpoint.RecordTypeTXT, "tag"),
+		endpoint.NewEndpoint("mail.example.com", endpoint.RecordTypeMX, "10 other.com"),
+		endpoint.NewEndpoint("mail.example.com", endpoint.RecordTypeTXT, "tag"),
 	}
 
 	currentRecords := []*endpoint.Endpoint{
 		endpoint.NewEndpoint("old.example.com", endpoint.RecordTypeA, "121.212.121.212"),
 		endpoint.NewEndpoint("oldcname.example.com", endpoint.RecordTypeCNAME, "other.com"),
 		endpoint.NewEndpoint("old.nope.com", endpoint.RecordTypeA, "121.212.121.212"),
+		endpoint.NewEndpoint("oldmail.example.com", endpoint.RecordTypeMX, "20 foo.other.com"),
 	}
 	updatedRecords := []*endpoint.Endpoint{
 		endpoint.NewEndpointWithTTL("new.example.com", endpoint.RecordTypeA, 3600, "111.222.111.222"),
 		endpoint.NewEndpointWithTTL("newcname.example.com", endpoint.RecordTypeCNAME, 10, "other.com"),
 		endpoint.NewEndpoint("new.nope.com", endpoint.RecordTypeA, "222.111.222.111"),
+		endpoint.NewEndpointWithTTL("newmail.example.com", endpoint.RecordTypeMX, 7200, "40 bar.other.com"),
 	}
 
 	deleteRecords := []*endpoint.Endpoint{
@@ -455,6 +480,7 @@ func TestAzureNameFilter(t *testing.T) {
 			createMockRecordSetWithTTL("test.nginx", endpoint.RecordTypeA, "123.123.123.123", 3600),
 			createMockRecordSetWithTTL("nginx", endpoint.RecordTypeA, "123.123.123.123", 3600),
 			createMockRecordSetWithTTL("nginx", endpoint.RecordTypeTXT, "heritage=external-dns,external-dns/owner=default", recordTTL),
+			createMockRecordSetWithTTL("mail.nginx", endpoint.RecordTypeMX, "20 example.com", recordTTL),
 			createMockRecordSetWithTTL("hack", endpoint.RecordTypeCNAME, "hack.azurewebsites.net", 10),
 		})
 	if err != nil {
@@ -470,6 +496,7 @@ func TestAzureNameFilter(t *testing.T) {
 		endpoint.NewEndpointWithTTL("test.nginx.example.com", endpoint.RecordTypeA, 3600, "123.123.123.123"),
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeA, 3600, "123.123.123.123"),
 		endpoint.NewEndpointWithTTL("nginx.example.com", endpoint.RecordTypeTXT, recordTTL, "heritage=external-dns,external-dns/owner=default"),
+		endpoint.NewEndpointWithTTL("mail.nginx.example.com", endpoint.RecordTypeMX, recordTTL, "20 example.com"),
 	}
 
 	validateAzureEndpoints(t, actual, expected)

provider/azure/common.go

@@ -0,0 +1,33 @@
+package azure
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/Azure/azure-sdk-for-go/services/dns/mgmt/2018-05-01/dns"
+	"github.com/Azure/azure-sdk-for-go/services/privatedns/mgmt/2018-09-01/privatedns"
+	"github.com/Azure/go-autorest/autorest/to"
+)
+
+// Helper function (shared with test code)
+func parseMxTarget[T dns.MxRecord | privatedns.MxRecord](mxTarget string) (T, error) {
+	targetParts := strings.SplitN(mxTarget, " ", 2)
+
+	if len(targetParts) != 2 {
+		return T{}, fmt.Errorf("mx target needs to be of form '10 example.com'")
+	}
+
+	preferenceRaw, exchange := targetParts[0], targetParts[1]
+	preference, err := strconv.ParseInt(preferenceRaw, 10, 32)
+
+	if err != nil {
+		return T{}, fmt.Errorf("invalid preference specified")
+	}
+	res := T{
+		Preference: to.Int32Ptr(int32(preference)),
+		Exchange:   to.StringPtr(exchange),
+	}
+
+	return res, nil
+}

provider/azure/common_test.go

@@ -0,0 +1,71 @@
+package azure
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/Azure/azure-sdk-for-go/services/dns/mgmt/2018-05-01/dns"
+	"github.com/Azure/azure-sdk-for-go/services/privatedns/mgmt/2018-09-01/privatedns"
+	"github.com/Azure/go-autorest/autorest/to"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_parseMxTarget(t *testing.T) {
+	type testCase[T interface {
+		dns.MxRecord | privatedns.MxRecord
+	}] struct {
+		name    string
+		args    string
+		want    T
+		wantErr assert.ErrorAssertionFunc
+	}
+
+	tests := []testCase[dns.MxRecord]{
+		{
+			name: "valid mx target",
+			args: "10 example.com",
+			want: dns.MxRecord{
+				Preference: to.Int32Ptr(int32(10)),
+				Exchange:   to.StringPtr("example.com"),
+			},
+			wantErr: assert.NoError,
+		},
+		{
+			name: "valid mx target with a subdomain",
+			args: "99 foo-bar.example.com",
+			want: dns.MxRecord{
+				Preference: to.Int32Ptr(int32(99)),
+				Exchange:   to.StringPtr("foo-bar.example.com"),
+			},
+			wantErr: assert.NoError,
+		},
+		{
+			name:    "invalid mx target with misplaced preference and exchange",
+			args:    "example.com 10",
+			want:    dns.MxRecord{},
+			wantErr: assert.Error,
+		},
+		{
+			name:    "invalid mx target without preference",
+			args:    "example.com",
+			want:    dns.MxRecord{},
+			wantErr: assert.Error,
+		},
+		{
+			name:    "invalid mx target with non numeric preference",
+			args:    "aa example.com",
+			want:    dns.MxRecord{},
+			wantErr: assert.Error,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseMxTarget[dns.MxRecord](tt.args)
+			if !tt.wantErr(t, err, fmt.Sprintf("parseMxTarget(%v)", tt.args)) {
+				return
+			}
+			assert.Equalf(t, tt.want, got, "parseMxTarget(%v)", tt.args)
+		})
+	}
+}

provider/google/google.go

@@ -213,7 +213,7 @@ func (p *GoogleProvider) Records(ctx context.Context) (endpoints []*endpoint.End
 
 	f := func(resp *dns.ResourceRecordSetsListResponse) error {
 		for _, r := range resp.Rrsets {
-			if !provider.SupportedRecordType(r.Type) {
+			if !p.SupportedRecordType(r.Type) {
 				continue
 			}
 			endpoints = append(endpoints, endpoint.NewEndpointWithTTL(r.Name, r.Type, endpoint.TTL(r.Ttl), r.Rrdatas...))
@@ -273,6 +273,16 @@ func (p *GoogleProvider) ApplyChanges(ctx context.Context, changes *plan.Changes
 	return p.submitChange(ctx, change)
 }
 
+// SupportedRecordType returns true if the record type is supported by the provider
+func (p *GoogleProvider) SupportedRecordType(recordType string) bool {
+	switch recordType {
+	case "MX":
+		return true
+	default:
+		return provider.SupportedRecordType(recordType)
+	}
+}
+
 // newFilteredRecords returns a collection of RecordSets based on the given endpoints and domainFilter.
 func (p *GoogleProvider) newFilteredRecords(endpoints []*endpoint.Endpoint) []*dns.ResourceRecordSet {
 	records := []*dns.ResourceRecordSet{}
@@ -447,6 +457,12 @@ func newRecord(ep *endpoint.Endpoint) *dns.ResourceRecordSet {
 		targets[0] = provider.EnsureTrailingDot(targets[0])
 	}
 
+	if ep.RecordType == endpoint.RecordTypeMX {
+		for i, mxRecord := range ep.Targets {
+			targets[i] = provider.EnsureTrailingDot(mxRecord)
+		}
+	}
+
 	// no annotation results in a Ttl of 0, default to 300 for backwards-compatibility
 	var ttl int64 = googleRecordTTL
 	if ep.RecordTTL.IsConfigured() {

provider/google/google_test.go

@@ -512,6 +512,7 @@ func TestNewFilteredRecords(t *testing.T) {
 		endpoint.NewEndpointWithTTL("update-test-cname.zone-1.ext-dns-test-2.gcp.zalan.do", endpoint.RecordTypeCNAME, 4000, "bar.elb.amazonaws.com"),
 		// test fallback to Ttl:300 when Ttl==0 :
 		endpoint.NewEndpointWithTTL("update-test.zone-1.ext-dns-test-2.gcp.zalan.do", endpoint.RecordTypeA, 0, "8.8.8.8"),
+		endpoint.NewEndpointWithTTL("update-test-mx.zone-1.ext-dns-test-2.gcp.zalan.do", endpoint.RecordTypeMX, 6000, "10 mail.elb.amazonaws.com"),
 		endpoint.NewEndpoint("delete-test.zone-1.ext-dns-test-2.gcp.zalan.do", endpoint.RecordTypeA, "8.8.8.8"),
 		endpoint.NewEndpoint("delete-test-cname.zone-1.ext-dns-test-2.gcp.zalan.do", endpoint.RecordTypeCNAME, "qux.elb.amazonaws.com"),
 	})
@@ -521,6 +522,7 @@ func TestNewFilteredRecords(t *testing.T) {
 		{Name: "delete-test.zone-2.ext-dns-test-2.gcp.zalan.do.", Rrdatas: []string{"8.8.4.4"}, Type: "A", Ttl: 120},
 		{Name: "update-test-cname.zone-1.ext-dns-test-2.gcp.zalan.do.", Rrdatas: []string{"bar.elb.amazonaws.com."}, Type: "CNAME", Ttl: 4000},
 		{Name: "update-test.zone-1.ext-dns-test-2.gcp.zalan.do.", Rrdatas: []string{"8.8.8.8"}, Type: "A", Ttl: 300},
+		{Name: "update-test-mx.zone-1.ext-dns-test-2.gcp.zalan.do.", Rrdatas: []string{"10 mail.elb.amazonaws.com."}, Type: "MX", Ttl: 6000},
 		{Name: "delete-test.zone-1.ext-dns-test-2.gcp.zalan.do.", Rrdatas: []string{"8.8.8.8"}, Type: "A", Ttl: 300},
 		{Name: "delete-test-cname.zone-1.ext-dns-test-2.gcp.zalan.do.", Rrdatas: []string{"qux.elb.amazonaws.com."}, Type: "CNAME", Ttl: 300},
 	})