packer-cn/common/ssh/key.go

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package ssh
import (
"encoding/pem"
"fmt"
"io/ioutil"
"os"
"golang.org/x/crypto/ssh"
)
// FileSigner returns an ssh.Signer for a key file.
func FileSigner(path string) (ssh.Signer, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
keyBytes, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
// We parse the private key on our own first so that we can
// show a nicer error if the private key has a password.
block, _ := pem.Decode(keyBytes)
if block == nil {
return nil, fmt.Errorf(
"Failed to read key '%s': no key found", path)
}
if block.Headers["Proc-Type"] == "4,ENCRYPTED" {
return nil, fmt.Errorf(
"Failed to read key '%s': password protected keys are\n"+
"not supported. Please decrypt the key prior to use.", path)
}
signer, err := ssh.ParsePrivateKey(keyBytes)
if err != nil {
return nil, fmt.Errorf("Error setting up SSH config: %s", err)
}
return signer, nil
}