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DNS SD: add srv record target and port meta labels (#7678) 

* DNS SD: add srv record target and port meta labels

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
This commit is contained in:
Julien Pivotto 2020-07-28 22:09:01 +02:00 committed by GitHub
parent 348ff4285f
commit 88bdb13c55
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 48 additions and 12 deletions
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17
discovery/dns/dns.go
View File

@ -35,7 +35,10 @@ import (
const (
resolvConf = "/etc/resolv.conf"
dnsNameLabel = model.MetaLabelPrefix + "dns_name"
dnsNameLabel = model.MetaLabelPrefix + "dns_name"
dnsSrvRecordPrefix = model.MetaLabelPrefix + "dns_srv_record_"
dnsSrvRecordTargetLabel = dnsSrvRecordPrefix + "target"
dnsSrvRecordPortLabel = dnsSrvRecordPrefix + "port"
// Constants for instrumentation.
namespace = "prometheus"
@ -183,9 +186,13 @@ func (d *Discovery) refreshOne(ctx context.Context, name string, ch chan<- *targ
}
for _, record := range response.Answer {
var target model.LabelValue
var target, dnsSrvRecordTarget, dnsSrvRecordPort model.LabelValue
switch addr := record.(type) {
case *dns.SRV:
dnsSrvRecordTarget = model.LabelValue(addr.Target)
dnsSrvRecordPort = model.LabelValue(fmt.Sprintf("%d", addr.Port))
// Remove the final dot from rooted DNS names to make them look more usual.
addr.Target = strings.TrimRight(addr.Target, ".")
@ -199,8 +206,10 @@ func (d *Discovery) refreshOne(ctx context.Context, name string, ch chan<- *targ
continue
}
tg.Targets = append(tg.Targets, model.LabelSet{
model.AddressLabel: target,
dnsNameLabel: model.LabelValue(name),
model.AddressLabel: target,
dnsNameLabel: model.LabelValue(name),
dnsSrvRecordTargetLabel: dnsSrvRecordTarget,
dnsSrvRecordPortLabel: dnsSrvRecordPort,
})
}

35
discovery/dns/dns_test.go
View File

@ -75,7 +75,12 @@ func TestDNS(t *testing.T) {
{
Source: "web.example.com.",
Targets: []model.LabelSet{
{"__address__": "192.0.2.2:80", "__meta_dns_name": "web.example.com."},
{
"__address__": "192.0.2.2:80",
"__meta_dns_name": "web.example.com.",
"__meta_dns_srv_record_target": "",
"__meta_dns_srv_record_port": "",
},
},
},
},
@ -100,7 +105,12 @@ func TestDNS(t *testing.T) {
{
Source: "web.example.com.",
Targets: []model.LabelSet{
{"__address__": "[::1]:80", "__meta_dns_name": "web.example.com."},
{
"__address__": "[::1]:80",
"__meta_dns_name": "web.example.com.",
"__meta_dns_srv_record_target": "",
"__meta_dns_srv_record_port": "",
},
},
},
},
@ -125,8 +135,18 @@ func TestDNS(t *testing.T) {
{
Source: "_mysql._tcp.db.example.com.",
Targets: []model.LabelSet{
{"__address__": "db1.example.com:3306", "__meta_dns_name": "_mysql._tcp.db.example.com."},
{"__address__": "db2.example.com:3306", "__meta_dns_name": "_mysql._tcp.db.example.com."},
{
"__address__": "db1.example.com:3306",
"__meta_dns_name": "_mysql._tcp.db.example.com.",
"__meta_dns_srv_record_target": "db1.example.com.",
"__meta_dns_srv_record_port": "3306",
},
{
"__address__": "db2.example.com:3306",
"__meta_dns_name": "_mysql._tcp.db.example.com.",
"__meta_dns_srv_record_target": "db2.example.com.",
"__meta_dns_srv_record_port": "3306",
},
},
},
},
@ -150,7 +170,12 @@ func TestDNS(t *testing.T) {
{
Source: "_mysql._tcp.db.example.com.",
Targets: []model.LabelSet{
{"__address__": "db1.example.com:3306", "__meta_dns_name": "_mysql._tcp.db.example.com."},
{
"__address__": "db1.example.com:3306",
"__meta_dns_name": "_mysql._tcp.db.example.com.",
"__meta_dns_srv_record_target": "db1.example.com.",
"__meta_dns_srv_record_port": "3306",
},
},
},
},

8
docs/configuration/configuration.md
View File

@ -589,9 +589,11 @@ This service discovery method only supports basic DNS A, AAAA and SRV record
queries, but not the advanced DNS-SD approach specified in
[RFC6763](https://tools.ietf.org/html/rfc6763).
During the [relabeling phase](#relabel_config), the meta label
`__meta_dns_name` is available on each target and is set to the
record name that produced the discovered target.
The following meta labels are available on targets during [relabeling](#relabel_config):
* `__meta_dns_name`: the record name that produced the discovered target.
* `__meta_dns_srv_record_target`: the target field of the SRV record
* `__meta_dns_srv_record_port`: the port field of the SRV record
```yaml
# A list of DNS domain names to be queried.