terraform/communicator/ssh/provisioner.go

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package ssh
import (
"encoding/pem"
"fmt"
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"io/ioutil"
"log"
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"net"
"os"
"time"
"github.com/hashicorp/terraform/terraform"
"github.com/mitchellh/go-homedir"
"github.com/mitchellh/mapstructure"
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"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
)
const (
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// DefaultUser is used if there is no user given
DefaultUser = "root"
// DefaultPort is used if there is no port given
DefaultPort = 22
// DefaultScriptPath is used as the path to copy the file to
// for remote execution if not provided otherwise.
DefaultScriptPath = "/tmp/terraform_%RAND%.sh"
// DefaultTimeout is used if there is no timeout given
DefaultTimeout = 5 * time.Minute
)
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// connectionInfo is decoded from the ConnInfo of the resource. These are the
// only keys we look at. If a KeyFile is given, that is used instead
// of a password.
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type connectionInfo struct {
User string
Password string
KeyFile string `mapstructure:"key_file"`
Host string
Port int
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Agent bool
Timeout string
ScriptPath string `mapstructure:"script_path"`
TimeoutVal time.Duration `mapstructure:"-"`
}
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// parseConnectionInfo is used to convert the ConnInfo of the InstanceState into
// a ConnectionInfo struct
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func parseConnectionInfo(s *terraform.InstanceState) (*connectionInfo, error) {
connInfo := &connectionInfo{}
decConf := &mapstructure.DecoderConfig{
WeaklyTypedInput: true,
Result: connInfo,
}
dec, err := mapstructure.NewDecoder(decConf)
if err != nil {
return nil, err
}
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if err := dec.Decode(s.Ephemeral.ConnInfo); err != nil {
return nil, err
}
// To default Agent to true, we need to check the raw string, since the
// decoded boolean can't represent "absence of config".
//
// And if SSH_AUTH_SOCK is not set, there's no agent to connect to, so we
// shouldn't try.
if s.Ephemeral.ConnInfo["agent"] == "" && os.Getenv("SSH_AUTH_SOCK") != "" {
connInfo.Agent = true
}
if connInfo.User == "" {
connInfo.User = DefaultUser
}
if connInfo.Port == 0 {
connInfo.Port = DefaultPort
}
if connInfo.ScriptPath == "" {
connInfo.ScriptPath = DefaultScriptPath
}
if connInfo.Timeout != "" {
connInfo.TimeoutVal = safeDuration(connInfo.Timeout, DefaultTimeout)
} else {
connInfo.TimeoutVal = DefaultTimeout
}
return connInfo, nil
}
// safeDuration returns either the parsed duration or a default value
func safeDuration(dur string, defaultDur time.Duration) time.Duration {
d, err := time.ParseDuration(dur)
if err != nil {
log.Printf("Invalid duration '%s', using default of %s", dur, defaultDur)
return defaultDur
}
return d
}
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// prepareSSHConfig is used to turn the *ConnectionInfo provided into a
// usable *SSHConfig for client initialization.
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func prepareSSHConfig(connInfo *connectionInfo) (*sshConfig, error) {
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var conn net.Conn
var err error
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sshConf := &ssh.ClientConfig{
User: connInfo.User,
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}
if connInfo.Agent {
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sshAuthSock := os.Getenv("SSH_AUTH_SOCK")
if sshAuthSock == "" {
return nil, fmt.Errorf("SSH Requested but SSH_AUTH_SOCK not-specified")
}
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conn, err = net.Dial("unix", sshAuthSock)
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if err != nil {
return nil, fmt.Errorf("Error connecting to SSH_AUTH_SOCK: %v", err)
}
// I need to close this but, later after all connections have been made
// defer conn.Close()
signers, err := agent.NewClient(conn).Signers()
if err != nil {
return nil, fmt.Errorf("Error getting keys from ssh agent: %v", err)
}
sshConf.Auth = append(sshConf.Auth, ssh.PublicKeys(signers...))
}
if connInfo.KeyFile != "" {
fullPath, err := homedir.Expand(connInfo.KeyFile)
if err != nil {
return nil, fmt.Errorf("Failed to expand home directory: %v", err)
}
key, err := ioutil.ReadFile(fullPath)
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if err != nil {
return nil, fmt.Errorf("Failed to read key file '%s': %v", connInfo.KeyFile, err)
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}
// 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(key)
if block == nil {
return nil, fmt.Errorf(
"Failed to read key '%s': no key found", connInfo.KeyFile)
}
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.", connInfo.KeyFile)
}
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signer, err := ssh.ParsePrivateKey(key)
if err != nil {
return nil, fmt.Errorf("Failed to parse key file '%s': %v", connInfo.KeyFile, err)
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}
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sshConf.Auth = append(sshConf.Auth, ssh.PublicKeys(signer))
}
if connInfo.Password != "" {
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sshConf.Auth = append(sshConf.Auth,
ssh.Password(connInfo.Password))
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sshConf.Auth = append(sshConf.Auth,
ssh.KeyboardInteractive(PasswordKeyboardInteractive(connInfo.Password)))
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}
host := fmt.Sprintf("%s:%d", connInfo.Host, connInfo.Port)
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config := &sshConfig{
config: sshConf,
connection: ConnectFunc("tcp", host),
sshAgentConn: conn,
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}
return config, nil
}