terraform/helper/resource/id.go

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package resource
import (
"crypto/rand"
"encoding/base32"
"fmt"
"strings"
)
const UniqueIdPrefix = `terraform-`
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// Helper for a resource to generate a unique identifier w/ default prefix
func UniqueId() string {
return PrefixedUniqueId(UniqueIdPrefix)
}
// Helper for a resource to generate a unique identifier w/ given prefix
//
// This uses a simple RFC 4122 v4 UUID with some basic cosmetic filters
// applied (base32, remove padding, downcase) to make visually distinguishing
// identifiers easier.
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func PrefixedUniqueId(prefix string) string {
return fmt.Sprintf("%s%s", prefix,
strings.ToLower(
strings.Replace(
base32.StdEncoding.EncodeToString(uuidV4()),
"=", "", -1)))
}
func uuidV4() []byte {
var uuid [16]byte
// Set all the other bits to randomly (or pseudo-randomly) chosen
// values.
rand.Read(uuid[:])
// Set the two most significant bits (bits 6 and 7) of the
// clock_seq_hi_and_reserved to zero and one, respectively.
uuid[8] = (uuid[8] | 0x80) & 0x8f
// Set the four most significant bits (bits 12 through 15) of the
// time_hi_and_version field to the 4-bit version number from Section 4.1.3.
uuid[6] = (uuid[6] | 0x40) & 0x4f
return uuid[:]
}