plugin/nomad: Add a Nomad plugin (#7467)

Signed-off-by: Olli Janatuinen <olli.janatuinen@gmail.com>

plugin/nomad/helpers.go

@@ -0,0 +1,68 @@
+package nomad
+
+import (
+	"net"
+
+	"github.com/hashicorp/nomad/api"
+	"github.com/miekg/dns"
+)
+
+func addSRVRecord(m *dns.Msg, s *api.ServiceRegistration, header dns.RR_Header, originalQName string, addr net.IP, ttl uint32) error {
+	srvRecord := &dns.SRV{
+		Hdr:      header,
+		Target:   originalQName,
+		Port:     uint16(s.Port),
+		Priority: 10,
+		Weight:   10,
+	}
+	m.Answer = append(m.Answer, srvRecord)
+
+	if addr.To4() == nil {
+		addExtrasToAAAARecord(m, originalQName, ttl, addr)
+	} else {
+		addExtrasToARecord(m, originalQName, ttl, addr)
+	}
+
+	return nil
+}
+
+func addExtrasToARecord(m *dns.Msg, originalQName string, ttl uint32, addr net.IP) {
+	header := dns.RR_Header{
+		Name:   originalQName,
+		Rrtype: dns.TypeA,
+		Class:  dns.ClassINET,
+		Ttl:    ttl,
+	}
+	m.Extra = append(m.Extra, &dns.A{Hdr: header, A: addr})
+}
+
+func addExtrasToAAAARecord(m *dns.Msg, originalQName string, ttl uint32, addr net.IP) {
+	header := dns.RR_Header{
+		Name:   originalQName,
+		Rrtype: dns.TypeAAAA,
+		Class:  dns.ClassINET,
+		Ttl:    ttl,
+	}
+	m.Extra = append(m.Extra, &dns.AAAA{Hdr: header, AAAA: addr})
+}
+
+func addARecord(m *dns.Msg, header dns.RR_Header, addr net.IP) {
+	m.Answer = append(m.Answer, &dns.A{Hdr: header, A: addr})
+}
+
+func addAAAARecord(m *dns.Msg, header dns.RR_Header, addr net.IP) {
+	m.Answer = append(m.Answer, &dns.AAAA{Hdr: header, AAAA: addr})
+}
+
+func createSOARecord(originalQName string, ttl uint32, zone string) *dns.SOA {
+	return &dns.SOA{
+		Hdr:     dns.RR_Header{Name: dns.Fqdn(originalQName), Rrtype: dns.TypeSOA, Class: dns.ClassINET, Ttl: ttl},
+		Ns:      dns.Fqdn("ns1." + originalQName),
+		Mbox:    dns.Fqdn("hostmaster." + zone),
+		Serial:  0,
+		Refresh: 3600,
+		Retry:   600,
+		Expire:  86400,
+		Minttl:  30,
+	}
+}