Merge pull request #288 from gmr/rfc-2782-srv-lookups
Add RFC-2782 style SRV lookups
This commit is contained in:
Armon Dadgar
commit
98b83d9c0d
|
|
@ -266,18 +266,33 @@ PARSE:
|
|||
goto INVALID
|
||||
}
|
||||
|
||||
// Extract the service
|
||||
service := labels[n-2]
|
||||
// Support RFC 2782 style syntax
|
||||
if n == 3 && strings.HasPrefix(labels[n-2], "_") && strings.HasPrefix(labels[n-3], "_") {
|
||||
|
||||
// Support "." in the label, re-join all the parts
|
||||
tag := ""
|
||||
if n >= 3 {
|
||||
tag = strings.Join(labels[:n-2], ".")
|
||||
// Grab the tag since we make nuke it if it's tcp
|
||||
tag := labels[n-2][1:]
|
||||
|
||||
// Treat _name._tcp.service.consul as a default, no need to filter on that tag
|
||||
if tag == "tcp" {
|
||||
tag = ""
|
||||
}
|
||||
|
||||
// _name._tag.service.consul
|
||||
d.serviceLookup(network, datacenter, labels[n-3][1:], tag, req, resp)
|
||||
|
||||
// Consul 0.3 and prior format for SRV queries
|
||||
} else {
|
||||
|
||||
// Support "." in the label, re-join all the parts
|
||||
tag := ""
|
||||
if n >= 3 {
|
||||
tag = strings.Join(labels[:n-2], ".")
|
||||
}
|
||||
|
||||
// tag[.tag].name.service.consul
|
||||
d.serviceLookup(network, datacenter, labels[n-2], tag, req, resp)
|
||||
}
|
||||
|
||||
// Handle lookup with and without tag
|
||||
d.serviceLookup(network, datacenter, service, tag, req, resp)
|
||||
|
||||
case "node":
|
||||
if len(labels) == 1 {
|
||||
goto INVALID
|
||||
|
|
|
|||
|
|
@ -1120,3 +1120,137 @@ func TestDNS_ServiceLookup_TTL(t *testing.T) {
|
|||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
}
|
||||
|
||||
func TestDNS_ServiceLookup_SRV_RFC(t *testing.T) {
|
||||
dir, srv := makeDNSServer(t)
|
||||
defer os.RemoveAll(dir)
|
||||
defer srv.agent.Shutdown()
|
||||
|
||||
testutil.WaitForLeader(t, srv.agent.RPC, "dc1")
|
||||
|
||||
// Register node
|
||||
args := &structs.RegisterRequest{
|
||||
Datacenter: "dc1",
|
||||
Node: "foo",
|
||||
Address: "127.0.0.1",
|
||||
Service: &structs.NodeService{
|
||||
Service: "db",
|
||||
Tags: []string{"master"},
|
||||
Port: 12345,
|
||||
},
|
||||
}
|
||||
|
||||
var out struct{}
|
||||
if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
|
||||
t.Fatalf("err: %v", err)
|
||||
}
|
||||
|
||||
m := new(dns.Msg)
|
||||
m.SetQuestion("_db._master.service.consul.", dns.TypeSRV)
|
||||
|
||||
c := new(dns.Client)
|
||||
addr, _ := srv.agent.config.ClientListener(srv.agent.config.Ports.DNS)
|
||||
in, _, err := c.Exchange(m, addr.String())
|
||||
if err != nil {
|
||||
t.Fatalf("err: %v", err)
|
||||
}
|
||||
|
||||
if len(in.Answer) != 1 {
|
||||
t.Fatalf("Bad: %#v", in)
|
||||
}
|
||||
|
||||
srvRec, ok := in.Answer[0].(*dns.SRV)
|
||||
if !ok {
|
||||
t.Fatalf("Bad: %#v", in.Answer[0])
|
||||
}
|
||||
if srvRec.Port != 12345 {
|
||||
t.Fatalf("Bad: %#v", srvRec)
|
||||
}
|
||||
if srvRec.Target != "foo.node.dc1.consul." {
|
||||
t.Fatalf("Bad: %#v", srvRec)
|
||||
}
|
||||
if srvRec.Hdr.Ttl != 0 {
|
||||
t.Fatalf("Bad: %#v", in.Answer[0])
|
||||
}
|
||||
|
||||
aRec, ok := in.Extra[0].(*dns.A)
|
||||
if !ok {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
if aRec.Hdr.Name != "foo.node.dc1.consul." {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
if aRec.A.String() != "127.0.0.1" {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
if aRec.Hdr.Ttl != 0 {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
}
|
||||
|
||||
func TestDNS_ServiceLookup_SRV_RFC_TCP_Default(t *testing.T) {
|
||||
dir, srv := makeDNSServer(t)
|
||||
defer os.RemoveAll(dir)
|
||||
defer srv.agent.Shutdown()
|
||||
|
||||
testutil.WaitForLeader(t, srv.agent.RPC, "dc1")
|
||||
|
||||
// Register node
|
||||
args := &structs.RegisterRequest{
|
||||
Datacenter: "dc1",
|
||||
Node: "foo",
|
||||
Address: "127.0.0.1",
|
||||
Service: &structs.NodeService{
|
||||
Service: "db",
|
||||
Tags: []string{"master"},
|
||||
Port: 12345,
|
||||
},
|
||||
}
|
||||
|
||||
var out struct{}
|
||||
if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
|
||||
t.Fatalf("err: %v", err)
|
||||
}
|
||||
|
||||
m := new(dns.Msg)
|
||||
m.SetQuestion("_db._tcp.service.consul.", dns.TypeSRV)
|
||||
|
||||
c := new(dns.Client)
|
||||
addr, _ := srv.agent.config.ClientListener(srv.agent.config.Ports.DNS)
|
||||
in, _, err := c.Exchange(m, addr.String())
|
||||
if err != nil {
|
||||
t.Fatalf("err: %v", err)
|
||||
}
|
||||
|
||||
if len(in.Answer) != 1 {
|
||||
t.Fatalf("Bad: %#v", in)
|
||||
}
|
||||
|
||||
srvRec, ok := in.Answer[0].(*dns.SRV)
|
||||
if !ok {
|
||||
t.Fatalf("Bad: %#v", in.Answer[0])
|
||||
}
|
||||
if srvRec.Port != 12345 {
|
||||
t.Fatalf("Bad: %#v", srvRec)
|
||||
}
|
||||
if srvRec.Target != "foo.node.dc1.consul." {
|
||||
t.Fatalf("Bad: %#v", srvRec)
|
||||
}
|
||||
if srvRec.Hdr.Ttl != 0 {
|
||||
t.Fatalf("Bad: %#v", in.Answer[0])
|
||||
}
|
||||
|
||||
aRec, ok := in.Extra[0].(*dns.A)
|
||||
if !ok {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
if aRec.Hdr.Name != "foo.node.dc1.consul." {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
if aRec.A.String() != "127.0.0.1" {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
if aRec.Hdr.Ttl != 0 {
|
||||
t.Fatalf("Bad: %#v", in.Extra[0])
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -73,9 +73,14 @@ the node.
|
|||
## Service Lookups
|
||||
|
||||
A service lookup is the alternate type of query. It is used to query for service
|
||||
providers. The format of a service lookup is like the following:
|
||||
providers and supports two mode of lookup, a strict RCF style lookup and the
|
||||
standard lookup.
|
||||
|
||||
<tag>.<service>.service.<datacenter>.<domain>
|
||||
### Standard Style Lookup
|
||||
|
||||
The format of a standard service lookup is like the following:
|
||||
|
||||
[tag.]<service>.service[.datacenter][.domain]
|
||||
|
||||
As with node lookups, the `datacenter` is optional, as is the `tag`. If no tag is
|
||||
provided, then no filtering is done on tag. So, if we want to find any redis service
|
||||
|
|
@ -114,6 +119,46 @@ SRV records.
|
|||
;; ADDITIONAL SECTION:
|
||||
foobar.node.dc1.consul. 0 IN A 10.1.10.12
|
||||
|
||||
### RFC-2782 Style Lookup
|
||||
|
||||
The format for RFC style lookups uses the following format:
|
||||
|
||||
_<service>._<protocol>.service[.datacenter][.domain]
|
||||
|
||||
Per [RFC-2782](https://www.ietf.org/rfc/rfc2782.txt), SRV queries should use
|
||||
underscores (_) as a prefix to the `service` and `protocol` values in a query to
|
||||
prevent DNS collisions. The `protocol` value can be any of the tags for a
|
||||
service or if the service has no tags, the value "tcp" should be used. If "tcp"
|
||||
is specified as the protocol, the query will not perform any tag filtering.
|
||||
|
||||
Other than the query format and default "tcp" protocol/tag value, the behavior
|
||||
of the RFC style lookup is the same as the standard style of lookup.
|
||||
|
||||
Using the RCF style lookup, If you registered the service "rabbitmq" on port
|
||||
5672 and tagged it with "amqp" you would query the SRV record as
|
||||
"_rabbitmq._amqp.service.consul" as illustrated in the example below:
|
||||
|
||||
$ dig @127.0.0.1 -p 8600 consul.service.consul SRV
|
||||
|
||||
; <<>> DiG 9.8.3-P1 <<>> @127.0.0.1 -p 8600 _rabbitmq._amqp.service.consul ANY
|
||||
; (1 server found)
|
||||
;; global options: +cmd
|
||||
;; Got answer:
|
||||
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52838
|
||||
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
|
||||
;; WARNING: recursion requested but not available
|
||||
|
||||
;; QUESTION SECTION:
|
||||
;_rabbitmq._amqp.service.consul. IN SRV
|
||||
|
||||
;; ANSWER SECTION:
|
||||
_rabbitmq._amqp.service.consul. 0 IN SRV 1 1 5672 rabbitmq.node1.dc1.consul.
|
||||
|
||||
;; ADDITIONAL SECTION:
|
||||
rabbitmq.node1.dc1.consul. 0 IN A 10.1.11.20
|
||||
|
||||
### UDP Based DNS Queries
|
||||
|
||||
When the DNS query is performed using UDP, Consul will truncate the results
|
||||
without setting the truncate bit. This is to prevent a redundant lookup over
|
||||
TCP which generate additional load. If the lookup is done over TCP, the results
|
||||
|
|
@ -125,4 +170,3 @@ By default, all DNS results served by Consul set a 0 TTL value. This disables
|
|||
caching of DNS results. However, there are many situations in which caching is
|
||||
desirable for performance and scalability. This is discussed more in the guide
|
||||
for [DNS Caching](/docs/guides/dns-cache.html).
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue