Set a default TTL for nomad-sourced records.

clouddns.go

@@ -150,7 +150,7 @@ func buildNomadDnsChange(dnsSpec *CloudDNSSpec, tasks []TaskInfo, pruneMissing b
 		})
 	}
 
-	nomad_rrs, err := buildTaskInfoToRrsets(fq_taskinfo)
+	nomad_rrs, err := buildTaskInfoToRrsets(fq_taskinfo, dnsSpec.default_ttl)
 	if err != nil {
 		log.Fatal("Converting Nomad RRs for zone:", dnsSpec.zone)
 	}
@@ -197,16 +197,19 @@ func buildNomadDnsChange(dnsSpec *CloudDNSSpec, tasks []TaskInfo, pruneMissing b
 	return ret, nil
 }
 
-func buildTaskInfoToRrsets(tasks []TaskInfo) ([]*dns.ResourceRecordSet, error) {
+func buildTaskInfoToRrsets(tasks []TaskInfo, default_ttl *int) ([]*dns.ResourceRecordSet, error) {
+	// Take a set of TaskInfo (essentially name to IP) and return a slice of ResourceRecordSet
+	// use default_ttl as the ttl of all records (nomad has no opinion on ttl).
 	ret := []*dns.ResourceRecordSet{}
 
 	for _, t := range tasks {
-		ret = mergeAnswerToRrsets(ret, t.jobid, t.ip)
+		ret = mergeAnswerToRrsets(ret, t.jobid, t.ip, *default_ttl)
 	}
 	return ret, nil
 }
 
-func mergeAnswerToRrsets(rrsets []*dns.ResourceRecordSet, name string, ip string) []*dns.ResourceRecordSet {
+func mergeAnswerToRrsets(rrsets []*dns.ResourceRecordSet, name string, ip string, default_ttl int) []*dns.ResourceRecordSet {
+	// merges an answer that point name to ip into these rrsets.
 	// Only handles simple A records.
 	for _, rr := range rrsets {
 		if rr.Name == name {
@@ -227,6 +230,7 @@ func mergeAnswerToRrsets(rrsets []*dns.ResourceRecordSet, name string, ip string
 	new_rr := &dns.ResourceRecordSet{
 		Name: name,
 		Type: "A",
+		Ttl:  int64(default_ttl),
 	}
 	new_rr.Rrdatas = []string{ip}
 	rrsets = append(rrsets, new_rr)

clouddns_test.go

@@ -190,9 +190,10 @@ func TestZoneFileFragment(t *testing.T) {
 
 func Test_mergeAnswerToRrsets(t *testing.T) {
 	type args struct {
-		rrsets []*dns.ResourceRecordSet
-		name   string
-		ip     string
+		rrsets      []*dns.ResourceRecordSet
+		name        string
+		ip          string
+		default_ttl int
 	}
 	tests := []struct {
 		name string
@@ -285,9 +286,9 @@ func Test_mergeAnswerToRrsets(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if got := mergeAnswerToRrsets(tt.args.rrsets, tt.args.name, tt.args.ip); !reflect.DeepEqual(got, tt.want) {
+			if got := mergeAnswerToRrsets(tt.args.rrsets, tt.args.name, tt.args.ip, tt.args.default_ttl); !reflect.DeepEqual(got, tt.want) {
 				for _, rr := range got {
-					t.Logf("Got: %s (%s), %d answers.", rr.Name, rr.Type, len(rr.Rrdatas))
+					t.Logf("Got: %s (%s) TTL %d, %d answers.", rr.Name, rr.Type, rr.Ttl, len(rr.Rrdatas))
 					for _, rrd := range rr.Rrdatas {
 						t.Logf("Got: - %s", rrd)
 					}

main.go

@@ -12,16 +12,19 @@ import (
 )
 
 type CloudDNSSpec struct {
-	svc     *dns.Service
-	project *string
-	zone    *string
-	domain  *string
+	svc         *dns.Service
+	project     *string
+	zone        *string
+	domain      *string
+	default_ttl *int
 }
 
 func main() {
 	var jsonKeyfile = flag.String("json-keyfile", "key.json", "json credentials file for Cloud DNS")
 	var cloudProject = flag.String("cloud-project", "", "Google Cloud Project")
 	var cloudZone = flag.String("cloud-dns-zone", "", "Cloud DNS zone to operate on")
+	var defaultCloudTtl = flag.Int("cloud-dns-default-ttl", 300, "Default TTL for Cloud DNS records")
+
 	var zoneFilename = flag.String("zonefilename", "", "Local zone file to operate on")
 	var dryRun = flag.Bool("dry-run", false, "Do not update Cloud DNS, print what would be done")
 	var pruneMissing = flag.Bool("prune-missing", false, "on putzonefile, prune cloud dns entries not in zone file")
@@ -71,9 +74,10 @@ func main() {
 	}
 
 	dns_spec := &CloudDNSSpec{
-		svc:     dnsservice,
-		project: cloudProject,
-		zone:    cloudZone,
+		svc:         dnsservice,
+		project:     cloudProject,
+		zone:        cloudZone,
+		default_ttl: defaultCloudTtl,
 	}
 
 	err = populateDnsSpec(dns_spec)