packer-cn/builder/amazon/common/ssm/session.go

118 lines
3.7 KiB
Go

package ssm
import (
"context"
"encoding/json"
"fmt"
"log"
"os/exec"
"strconv"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/ssm"
"github.com/aws/aws-sdk-go/service/ssm/ssmiface"
"github.com/hashicorp/packer/builder/amazon/common/awserrors"
packersdk "github.com/hashicorp/packer/packer-plugin-sdk/packer"
"github.com/hashicorp/packer/packer-plugin-sdk/retry"
"github.com/hashicorp/packer/packer-plugin-sdk/shell-local/localexec"
)
type Session struct {
SvcClient ssmiface.SSMAPI
Region string
InstanceID string
LocalPort, RemotePort int
}
func (s Session) buildTunnelInput() *ssm.StartSessionInput {
portNumber, localPortNumber := strconv.Itoa(s.RemotePort), strconv.Itoa(s.LocalPort)
params := map[string][]*string{
"portNumber": []*string{aws.String(portNumber)},
"localPortNumber": []*string{aws.String(localPortNumber)},
}
return &ssm.StartSessionInput{
DocumentName: aws.String("AWS-StartPortForwardingSession"),
Parameters: params,
Target: aws.String(s.InstanceID),
}
}
// getCommand return a valid ordered set of arguments to pass to the driver command.
func (s Session) getCommand(ctx context.Context) ([]string, string, error) {
input := s.buildTunnelInput()
var session *ssm.StartSessionOutput
err := retry.Config{
ShouldRetry: func(err error) bool { return awserrors.Matches(err, "TargetNotConnected", "") },
RetryDelay: (&retry.Backoff{InitialBackoff: 200 * time.Millisecond, MaxBackoff: 60 * time.Second, Multiplier: 2}).Linear,
}.Run(ctx, func(ctx context.Context) (err error) {
session, err = s.SvcClient.StartSessionWithContext(ctx, input)
return err
})
if err != nil {
return nil, "", err
}
if session == nil {
return nil, "", fmt.Errorf("an active Amazon SSM Session is required before trying to open a session tunnel")
}
// AWS session-manager-plugin requires a valid session be passed in JSON.
sessionDetails, err := json.Marshal(session)
if err != nil {
return nil, *session.SessionId, fmt.Errorf("error encountered in reading session details %s", err)
}
// AWS session-manager-plugin requires the parameters used in the session to be passed in JSON as well.
sessionParameters, err := json.Marshal(input)
if err != nil {
return nil, "", fmt.Errorf("error encountered in reading session parameter details %s", err)
}
// Args must be in this order
args := []string{
string(sessionDetails),
s.Region,
"StartSession",
"", // ProfileName
string(sessionParameters),
*session.StreamUrl,
}
return args, *session.SessionId, nil
}
// Start an interactive Systems Manager session with a remote instance via the
// AWS session-manager-plugin. To terminate the session you must cancell the
// context. If you do not wish to terminate the session manually: calling
// StopSession on a instance of this driver will terminate the active session
// created from calling StartSession.
func (s Session) Start(ctx context.Context, ui packersdk.Ui) error {
for ctx.Err() == nil {
log.Printf("ssm: Starting PortForwarding session to instance %s", s.InstanceID)
args, sessionID, err := s.getCommand(ctx)
if sessionID != "" {
defer func() {
_, err := s.SvcClient.TerminateSession(&ssm.TerminateSessionInput{SessionId: aws.String(sessionID)})
if err != nil {
ui.Error(fmt.Sprintf("Error terminating SSM Session %q. Please terminate the session manually: %s", sessionID, err))
}
}()
}
if err != nil {
return err
}
cmd := exec.CommandContext(ctx, "session-manager-plugin", args...)
ui.Message(fmt.Sprintf("Starting portForwarding session %q.", sessionID))
err = localexec.RunAndStream(cmd, ui, nil)
if err != nil {
ui.Error(err.Error())
}
}
return nil
}