packer-cn/builder/amazon/common/step_create_ssm_tunnel.go

127 lines
3.3 KiB
Go

package common
import (
"context"
"fmt"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/ec2"
"github.com/aws/aws-sdk-go/service/ssm"
"github.com/hashicorp/packer-plugin-sdk/multistep"
"github.com/hashicorp/packer-plugin-sdk/net"
packersdk "github.com/hashicorp/packer-plugin-sdk/packer"
pssm "github.com/hashicorp/packer/builder/amazon/common/ssm"
)
type StepCreateSSMTunnel struct {
AWSSession *session.Session
Region string
LocalPortNumber int
RemotePortNumber int
SSMAgentEnabled bool
PauseBeforeSSM time.Duration
stopSSMCommand func()
}
// Run executes the Packer build step that creates a session tunnel.
func (s *StepCreateSSMTunnel) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
ui := state.Get("ui").(packersdk.Ui)
if !s.SSMAgentEnabled {
return multistep.ActionContinue
}
// Wait for the remote port to become available
if s.PauseBeforeSSM > 0 {
ui.Say(fmt.Sprintf("Waiting %s before establishing the SSM session...", s.PauseBeforeSSM))
select {
case <-time.After(s.PauseBeforeSSM):
break
case <-ctx.Done():
return multistep.ActionHalt
}
}
// Configure local port number
if err := s.ConfigureLocalHostPort(ctx); err != nil {
err := fmt.Errorf("error finding an available port to initiate a session tunnel: %s", err)
state.Put("error", err)
ui.Error(err.Error())
return multistep.ActionHalt
}
// Get instance information
instance, ok := state.Get("instance").(*ec2.Instance)
if !ok {
err := fmt.Errorf("error encountered in obtaining target instance id for session tunnel")
ui.Error(err.Error())
state.Put("error", err)
return multistep.ActionHalt
}
state.Put("sessionPort", s.LocalPortNumber)
ssmCtx, ssmCancel := context.WithCancel(ctx)
s.stopSSMCommand = ssmCancel
go func() {
ssmconn := ssm.New(s.AWSSession)
err := pssm.Session{
SvcClient: ssmconn,
InstanceID: aws.StringValue(instance.InstanceId),
RemotePort: s.RemotePortNumber,
LocalPort: s.LocalPortNumber,
Region: s.Region,
}.Start(ssmCtx, ui)
if err != nil {
ui.Error(fmt.Sprintf("ssm error: %s", err))
}
}()
return multistep.ActionContinue
}
// Cleanup terminates an active session on AWS, which in turn terminates the associated tunnel process running on the local machine.
func (s *StepCreateSSMTunnel) Cleanup(state multistep.StateBag) {
if !s.SSMAgentEnabled {
return
}
if s.stopSSMCommand != nil {
s.stopSSMCommand()
}
}
// ConfigureLocalHostPort finds an available port on the localhost that can be used for the remote tunnel.
// Defaults to using s.LocalPortNumber if it is set.
func (s *StepCreateSSMTunnel) ConfigureLocalHostPort(ctx context.Context) error {
minPortNumber, maxPortNumber := 8000, 9000
if s.LocalPortNumber != 0 {
minPortNumber = s.LocalPortNumber
maxPortNumber = minPortNumber
}
// Find an available TCP port for our HTTP server
l, err := net.ListenRangeConfig{
Min: minPortNumber,
Max: maxPortNumber,
Addr: "0.0.0.0",
Network: "tcp",
}.Listen(ctx)
if err != nil {
return err
}
s.LocalPortNumber = l.Port
// Stop listening on selected port so that the AWS session-manager-plugin can use it.
// The port is closed right before we start the session to avoid two Packer builds from getting the same port - fingers-crossed
l.Close()
return nil
}