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
|
// Package stringid provides helper functions for dealing with string identifiers
package stringid
import (
"crypto/rand"
"encoding/hex"
"strings"
)
const (
shortLen = 12
fullLen = 64
)
// TruncateID returns a shorthand version of a string identifier for convenience.
// A collision with other shorthands is very unlikely, but possible.
// In case of a collision a lookup with TruncIndex.Get() will fail, and the caller
// will need to use a longer prefix, or the full-length Id.
func TruncateID(id string) string {
if i := strings.IndexRune(id, ':'); i >= 0 {
id = id[i+1:]
}
if len(id) > shortLen {
id = id[:shortLen]
}
return id
}
// GenerateRandomID returns a unique, 64-character ID consisting of a-z, 0-9.
// It guarantees that the ID, when truncated ([TruncateID]) does not consist
// of numbers only, so that the truncated ID can be used as hostname for
// containers.
func GenerateRandomID() string {
b := make([]byte, 32)
for {
if _, err := rand.Read(b); err != nil {
panic(err) // This shouldn't happen
}
id := hex.EncodeToString(b)
// make sure that the truncated ID does not consist of only numeric
// characters, as it's used as default hostname for containers.
//
// See:
// - https://github.com/moby/moby/issues/3869
// - https://bugzilla.redhat.com/show_bug.cgi?id=1059122
if allNum(id[:shortLen]) {
// all numbers; try again
continue
}
return id
}
}
// allNum checks whether id consists of only numbers (0-9).
func allNum(id string) bool {
for _, c := range []byte(id) {
if c > '9' || c < '0' {
return false
}
}
return true
}
|
