terraform/helper/acctest/random.go

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package acctest
import (
"bufio"
"bytes"
crand "crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"fmt"
"math/rand"
"strings"
"time"
"golang.org/x/crypto/ssh"
)
// Helpers for generating random tidbits for use in identifiers to prevent
// collisions in acceptance tests.
// RandInt generates a random integer
func RandInt() int {
reseed()
return rand.New(rand.NewSource(time.Now().UnixNano())).Int()
}
// RandString generates a random alphanumeric string of the length specified
func RandString(strlen int) string {
return RandStringFromCharSet(strlen, CharSetAlphaNum)
}
// RandStringFromCharSet generates a random string by selecting characters from
// the charset provided
func RandStringFromCharSet(strlen int, charSet string) string {
reseed()
result := make([]byte, strlen)
for i := 0; i < strlen; i++ {
result[i] = charSet[rand.Intn(len(charSet))]
}
return string(result)
}
// RandSSHKeyPair generates a public and private SSH key pair. The public key is
// returned in OpenSSH format, and the private key is PEM encoded.
func RandSSHKeyPair(comment string) (string, string, error) {
privateKey, err := rsa.GenerateKey(crand.Reader, 1024)
if err != nil {
return "", "", err
}
var privateKeyBuffer bytes.Buffer
privateKeyPEM := &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(privateKey)}
if err := pem.Encode(bufio.NewWriter(&privateKeyBuffer), privateKeyPEM); err != nil {
return "", "", err
}
publicKey, err := ssh.NewPublicKey(&privateKey.PublicKey)
if err != nil {
return "", "", err
}
keyMaterial := strings.TrimSpace(string(ssh.MarshalAuthorizedKey(publicKey)))
return fmt.Sprintf("%s %s", keyMaterial, comment), privateKeyBuffer.String(), nil
}
// Seeds random with current timestamp
func reseed() {
rand.Seed(time.Now().UTC().UnixNano())
}
const (
// CharSetAlphaNum is the alphanumeric character set for use with
// RandStringFromCharSet
CharSetAlphaNum = "abcdefghijklmnopqrstuvwxyz012346789"
// CharSetAlpha is the alphabetical character set for use with
// RandStringFromCharSet
CharSetAlpha = "abcdefghijklmnopqrstuvwxyz"
)