prometheus/discovery/dns/dns_test.go

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// Copyright 2019 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package dns
import (
"context"
"fmt"
"net"
"testing"
"time"
"github.com/go-kit/kit/log"
"github.com/miekg/dns"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/discovery/targetgroup"
"github.com/prometheus/prometheus/util/testutil"
)
func TestDNS(t *testing.T) {
testCases := []struct {
name string
config SDConfig
lookup func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error)
expected []*targetgroup.Group
}{
{
name: "A record query with error",
config: SDConfig{
Names: []string{"web.example.com."},
RefreshInterval: model.Duration(time.Minute),
Port: 80,
Type: "A",
},
lookup: func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error) {
return nil, fmt.Errorf("some error")
},
expected: []*targetgroup.Group{},
},
{
name: "A record query",
config: SDConfig{
Names: []string{"web.example.com."},
RefreshInterval: model.Duration(time.Minute),
Port: 80,
Type: "A",
},
lookup: func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error) {
return &dns.Msg{
Answer: []dns.RR{
&dns.A{A: net.IPv4(192, 0, 2, 2)},
},
},
nil
},
expected: []*targetgroup.Group{
{
Source: "web.example.com.",
Targets: []model.LabelSet{
{"__address__": "192.0.2.2:80", "__meta_dns_name": "web.example.com."},
},
},
},
},
{
name: "AAAA record query",
config: SDConfig{
Names: []string{"web.example.com."},
RefreshInterval: model.Duration(time.Minute),
Port: 80,
Type: "AAAA",
},
lookup: func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error) {
return &dns.Msg{
Answer: []dns.RR{
&dns.AAAA{AAAA: net.IPv6loopback},
},
},
nil
},
expected: []*targetgroup.Group{
{
Source: "web.example.com.",
Targets: []model.LabelSet{
{"__address__": "[::1]:80", "__meta_dns_name": "web.example.com."},
},
},
},
},
{
name: "SRV record query",
config: SDConfig{
Names: []string{"_mysql._tcp.db.example.com."},
RefreshInterval: model.Duration(time.Minute),
},
lookup: func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error) {
return &dns.Msg{
Answer: []dns.RR{
&dns.SRV{Port: 3306, Target: "db1.example.com."},
&dns.SRV{Port: 3306, Target: "db2.example.com."},
},
},
nil
},
expected: []*targetgroup.Group{
{
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."},
},
},
},
},
{
name: "SRV record query with unsupported resource records",
config: SDConfig{
Names: []string{"_mysql._tcp.db.example.com."},
RefreshInterval: model.Duration(time.Minute),
},
lookup: func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error) {
return &dns.Msg{
Answer: []dns.RR{
&dns.SRV{Port: 3306, Target: "db1.example.com."},
&dns.TXT{Txt: []string{"this should be discarded"}},
},
},
nil
},
expected: []*targetgroup.Group{
{
Source: "_mysql._tcp.db.example.com.",
Targets: []model.LabelSet{
{"__address__": "db1.example.com:3306", "__meta_dns_name": "_mysql._tcp.db.example.com."},
},
},
},
},
{
name: "SRV record query with empty answer (NXDOMAIN)",
config: SDConfig{
Names: []string{"_mysql._tcp.db.example.com."},
RefreshInterval: model.Duration(time.Minute),
},
lookup: func(name string, qtype uint16, logger log.Logger) (*dns.Msg, error) {
return &dns.Msg{}, nil
},
expected: []*targetgroup.Group{
{
Source: "_mysql._tcp.db.example.com.",
},
},
},
}
for _, tc := range testCases {
tc := tc
t.Run(tc.name, func(t *testing.T) {
t.Parallel()
sd := NewDiscovery(tc.config, nil)
sd.lookupFn = tc.lookup
tgs, err := sd.refresh(context.Background())
testutil.Ok(t, err)
testutil.Equals(t, tc.expected, tgs)
})
}
}