support ExternalID in AWS Provider when assuming a role

main.go

@@ -196,6 +196,7 @@ func main() {
 				BatchChangeInterval:  cfg.AWSBatchChangeInterval,
 				EvaluateTargetHealth: cfg.AWSEvaluateTargetHealth,
 				AssumeRole:           cfg.AWSAssumeRole,
+				AssumeRoleExternalId: cfg.AWSAssumeRoleExternalId,
 				APIRetries:           cfg.AWSAPIRetries,
 				PreferCNAME:          cfg.AWSPreferCNAME,
 				DryRun:               cfg.DryRun,
@@ -208,7 +209,7 @@ func main() {
 			log.Infof("Registry \"%s\" cannot be used with AWS Cloud Map. Switching to \"aws-sd\".", cfg.Registry)
 			cfg.Registry = "aws-sd"
 		}
-		p, err = awssd.NewAWSSDProvider(domainFilter, cfg.AWSZoneType, cfg.AWSAssumeRole, cfg.DryRun, cfg.AWSSDServiceCleanup, cfg.TXTOwnerID)
+		p, err = awssd.NewAWSSDProvider(domainFilter, cfg.AWSZoneType, cfg.AWSAssumeRole, cfg.AWSAssumeRoleExternalId, cfg.DryRun, cfg.AWSSDServiceCleanup, cfg.TXTOwnerID)
 	case "azure-dns", "azure":
 		p, err = azure.NewAzureProvider(cfg.AzureConfigFile, domainFilter, zoneNameFilter, zoneIDFilter, cfg.AzureResourceGroup, cfg.AzureUserAssignedIdentityClientID, cfg.DryRun)
 	case "azure-private-dns":

pkg/apis/externaldns/types.go

@@ -83,6 +83,7 @@ type Config struct {
 	AWSZoneType                       string
 	AWSZoneTagFilter                  []string
 	AWSAssumeRole                     string
+	AWSAssumeRoleExternalId           string
 	AWSBatchChangeSize                int
 	AWSBatchChangeInterval            time.Duration
 	AWSEvaluateTargetHealth           bool
@@ -227,6 +228,7 @@ var defaultConfig = &Config{
 	AWSZoneType:                 "",
 	AWSZoneTagFilter:            []string{},
 	AWSAssumeRole:               "",
+	AWSAssumeRoleExternalId:     "",
 	AWSBatchChangeSize:          1000,
 	AWSBatchChangeInterval:      time.Second,
 	AWSEvaluateTargetHealth:     true,
@@ -423,6 +425,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("aws-zone-type", "When using the AWS provider, filter for zones of this type (optional, options: public, private)").Default(defaultConfig.AWSZoneType).EnumVar(&cfg.AWSZoneType, "", "public", "private")
 	app.Flag("aws-zone-tags", "When using the AWS provider, filter for zones with these tags").Default("").StringsVar(&cfg.AWSZoneTagFilter)
 	app.Flag("aws-assume-role", "When using the AWS provider, assume this IAM role. Useful for hosted zones in another AWS account. Specify the full ARN, e.g. `arn:aws:iam::123455567:role/external-dns` (optional)").Default(defaultConfig.AWSAssumeRole).StringVar(&cfg.AWSAssumeRole)
+	app.Flag("aws-assume-role-external-id", "When using the AWS provider and assuming a role then specify this external id` (optional)").Default(defaultConfig.AWSAssumeRoleExternalId).StringVar(&cfg.AWSAssumeRoleExternalId)
 	app.Flag("aws-batch-change-size", "When using the AWS provider, set the maximum number of changes that will be applied in each batch.").Default(strconv.Itoa(defaultConfig.AWSBatchChangeSize)).IntVar(&cfg.AWSBatchChangeSize)
 	app.Flag("aws-batch-change-interval", "When using the AWS provider, set the interval between batch changes.").Default(defaultConfig.AWSBatchChangeInterval.String()).DurationVar(&cfg.AWSBatchChangeInterval)
 	app.Flag("aws-evaluate-target-health", "When using the AWS provider, set whether to evaluate the health of a DNS target (default: enabled, disable with --no-aws-evaluate-target-health)").Default(strconv.FormatBool(defaultConfig.AWSEvaluateTargetHealth)).BoolVar(&cfg.AWSEvaluateTargetHealth)

pkg/apis/externaldns/types_test.go

@@ -57,6 +57,7 @@ var (
 		AWSZoneType:                 "",
 		AWSZoneTagFilter:            []string{""},
 		AWSAssumeRole:               "",
+		AWSAssumeRoleExternalId:     "",
 		AWSBatchChangeSize:          1000,
 		AWSBatchChangeInterval:      time.Second,
 		AWSEvaluateTargetHealth:     true,
@@ -157,6 +158,7 @@ var (
 		AWSZoneType:                 "private",
 		AWSZoneTagFilter:            []string{"tag=foo"},
 		AWSAssumeRole:               "some-other-role",
+		AWSAssumeRoleExternalId:     "pg2000",
 		AWSBatchChangeSize:          100,
 		AWSBatchChangeInterval:      time.Second * 2,
 		AWSEvaluateTargetHealth:     false,
@@ -326,6 +328,7 @@ func TestParseFlags(t *testing.T) {
 				"--aws-zone-type=private",
 				"--aws-zone-tags=tag=foo",
 				"--aws-assume-role=some-other-role",
+				"--aws-assume-role-external-id=pg2000",
 				"--aws-batch-change-size=100",
 				"--aws-batch-change-interval=2s",
 				"--aws-api-retries=13",
@@ -438,6 +441,7 @@ func TestParseFlags(t *testing.T) {
 				"EXTERNAL_DNS_AWS_ZONE_TYPE":                   "private",
 				"EXTERNAL_DNS_AWS_ZONE_TAGS":                   "tag=foo",
 				"EXTERNAL_DNS_AWS_ASSUME_ROLE":                 "some-other-role",
+				"EXTERNAL_DNS_AWS_ASSUME_ROLE_EXTERNAL_ID":     "pg2000",
 				"EXTERNAL_DNS_AWS_BATCH_CHANGE_SIZE":           "100",
 				"EXTERNAL_DNS_AWS_BATCH_CHANGE_INTERVAL":       "2s",
 				"EXTERNAL_DNS_AWS_EVALUATE_TARGET_HEALTH":      "0",

provider/aws/aws.go

@@ -170,6 +170,7 @@ type AWSConfig struct {
 	BatchChangeInterval  time.Duration
 	EvaluateTargetHealth bool
 	AssumeRole           string
+	AssumeRoleExternalId string
 	APIRetries           int
 	PreferCNAME          bool
 	DryRun               bool
@@ -199,7 +200,13 @@ func NewAWSProvider(awsConfig AWSConfig) (*AWSProvider, error) {
 
 	if awsConfig.AssumeRole != "" {
 		log.Infof("Assuming role: %s", awsConfig.AssumeRole)
-		session.Config.WithCredentials(stscreds.NewCredentials(session, awsConfig.AssumeRole))
+		if awsConfig.AssumeRole != "" {
+			session.Config.WithCredentials(stscreds.NewCredentials(session, awsConfig.AssumeRole, func(p *stscreds.AssumeRoleProvider) {
+				p.ExternalID = &awsConfig.AssumeRoleExternalId
+			}))
+		} else {
+			session.Config.WithCredentials(stscreds.NewCredentials(session, awsConfig.AssumeRole))
+		}
 	}
 
 	provider := &AWSProvider{

provider/awssd/aws_sd.go

@@ -88,7 +88,7 @@ type AWSSDProvider struct {
 }
 
 // NewAWSSDProvider initializes a new AWS Cloud Map based Provider.
-func NewAWSSDProvider(domainFilter endpoint.DomainFilter, namespaceType string, assumeRole string, dryRun, cleanEmptyService bool, ownerID string) (*AWSSDProvider, error) {
+func NewAWSSDProvider(domainFilter endpoint.DomainFilter, namespaceType string, assumeRole string, assumeRoleExternalId string, dryRun, cleanEmptyService bool, ownerID string) (*AWSSDProvider, error) {
 	config := aws.NewConfig()
 
 	config = config.WithHTTPClient(
@@ -109,8 +109,15 @@ func NewAWSSDProvider(domainFilter endpoint.DomainFilter, namespaceType string,
 	}
 
 	if assumeRole != "" {
-		log.Infof("Assuming role: %s", assumeRole)
+		if assumeRoleExternalId != "" {
-		sess.Config.WithCredentials(stscreds.NewCredentials(sess, assumeRole))
+			log.Infof("Assuming role: %s with external id", assumeRole)
+			sess.Config.WithCredentials(stscreds.NewCredentials(sess, assumeRole, func(p *stscreds.AssumeRoleProvider) {
+				p.ExternalID = &assumeRoleExternalId
+			}))
+		} else {
+			log.Infof("Assuming role: %s", assumeRole)
+			sess.Config.WithCredentials(stscreds.NewCredentials(sess, assumeRole))
+		}
 	}
 
 	sess.Handlers.Build.PushBack(request.MakeAddToUserAgentHandler("ExternalDNS", externaldns.Version))