-
Notifications
You must be signed in to change notification settings - Fork 4
/
vpcinfo.go
211 lines (178 loc) · 4.4 KB
/
vpcinfo.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
// Package vpcinfo provides APIs to extract VPC information from DNS resolvers.
//
// The library abstract parsing and caching of VPC information resolved from TXT
// records, as configured by the terraform modules in this repository.
package vpcinfo
import (
"context"
"fmt"
"io/ioutil"
"net"
"net/http"
"net/url"
"os"
"reflect"
"strings"
"time"
)
// DefaultRegistry is the default registry used by top-level functions of this
// package.
var DefaultRegistry = &Registry{
Resolver: ResolverWithDomain(DefaultDomain, net.DefaultResolver),
Timeout: 2 * time.Second,
TTL: 1 * time.Minute,
}
// LookupPlatform returns the name of the VPC platform.
func LookupPlatform() (Platform, error) {
return DefaultRegistry.LookupPlatform(context.Background())
}
// LookupSubnets returns the list of subnets in the VPC.
func LookupSubnets() (Subnets, error) {
return DefaultRegistry.LookupSubnets(context.Background())
}
// LookupZone returns the name of the current VPC zone.
func LookupZone() (Zone, error) {
return DefaultRegistry.LookupZone(context.Background())
}
func parse(s string, x interface{}) error {
v := reflect.ValueOf(x).Elem()
t := v.Type()
fields := make(map[string][]int)
for i, n := 0, t.NumField(); i < n; i++ {
f := t.Field(i)
s := f.Tag.Get("name")
if s != "" {
fields[s] = f.Index
}
}
q, err := url.ParseQuery(s)
if err != nil {
return err
}
for name, values := range q {
for _, value := range values {
if f, ok := fields[name]; ok {
field := v.FieldByIndex(f)
switch x := field.Addr().Interface().(type) {
case *string:
*x = value
case **net.IPNet:
_, *x, err = net.ParseCIDR(value)
default:
// TODO: add types as needed
err = fmt.Errorf("found unsupported field type: %s", field.Type())
}
if err != nil {
return err
}
}
}
}
return nil
}
func splitNameAndValue(s string) (string, string) {
i := strings.IndexByte(s, '=')
if i < 0 {
return s, ""
}
return s[:i], s[i+1:]
}
// Platform is an interface representing the VPC platform that the program is
// running.
type Platform interface {
// Returns the name of the platform.
String() string
// Returns the zone that the program is running in.
LookupZone(context.Context) (Zone, error)
}
// Zone is a string type representing infrastructure zones.
type Zone string
// String returns z as a string value, satisfies the fmt.Stringer interface.
func (z Zone) String() string { return string(z) }
func zoneFromSubnets(subnets []Subnet) (Zone, error) {
addrs, err := net.InterfaceAddrs()
if err != nil {
return "", err
}
for _, addr := range addrs {
var ip net.IP
switch v := addr.(type) {
case *net.IPNet:
ip = v.IP
case *net.IPAddr:
ip = v.IP
}
for _, subnet := range subnets {
if subnet.CIDR.Contains(ip) {
return Zone(subnet.Zone), nil
}
}
}
return "", nil
}
func zoneFromMetadata() (Zone, error) {
r, err := httpClient.Get(
"http://169.254.169.254/latest/meta-data/placement/availability-zone",
)
if err != nil {
return "", err
}
defer r.Body.Close()
b, err := ioutil.ReadAll(r.Body)
if err != nil {
return "", err
}
return Zone(b), err
}
func whereAmI(subnets []Subnet) (Platform, error) {
// https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/identify_ec2_instances.html
for _, path := range [...]string{
"/sys/devices/virtual/dmi/id/product_uuid",
"/sys/hypervisor/uuid",
} {
b, err := ioutil.ReadFile(path)
if err != nil {
if os.IsNotExist(err) {
continue
}
return nil, err
}
s := string(b)
switch {
case strings.HasPrefix(s, "EC2"), strings.HasPrefix(s, "ec2"):
zone, err := zoneFromSubnets(subnets)
if err != nil {
return nil, err
}
if zone != "" {
return aws{zone}, nil
}
zone, err = zoneFromMetadata()
if err != nil {
return nil, err
}
return aws{zone}, nil
}
}
return unknown{}, nil
}
type aws struct {
zone Zone
}
func (aws) String() string { return "aws" }
func (a aws) LookupZone(ctx context.Context) (Zone, error) {
return a.zone, nil
}
type unknown struct{}
func (unknown) String() string { return "unknown" }
func (unknown) LookupZone(ctx context.Context) (Zone, error) { return "", ctx.Err() }
var httpClient = &http.Client{
Transport: &http.Transport{
DisableCompression: true,
DisableKeepAlives: true,
},
}
type endpoints map[string]string
func (e endpoints) String() string {
return fmt.Sprintf("list of %d resource(s)", len(e))
}