Move ssm code to its own ssm package and make it singlethreaded

This commit is contained in:
Adrien Delorme 2020-10-29 11:48:43 +01:00
parent 646b973bd3
commit 8e355d0fe7
7 changed files with 152 additions and 236 deletions

View File

@ -0,0 +1,111 @@
package ssm
import (
"context"
"encoding/json"
"fmt"
"log"
"os/exec"
"strings"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/service/ssm"
"github.com/aws/aws-sdk-go/service/ssm/ssmiface"
"github.com/hashicorp/packer/common/retry"
"github.com/hashicorp/packer/helper/builder/localexec"
"github.com/hashicorp/packer/packer"
)
type Session struct {
SvcClient ssmiface.SSMAPI
Region string
Input ssm.StartSessionInput
}
// Returns true if the error matches all these conditions:
// * err is of type awserr.Error
// * Error.Code() matches code
// * Error.Message() contains message
func isAWSErr(err error, code string, message string) bool {
if err, ok := err.(awserr.Error); ok {
return err.Code() == code && strings.Contains(err.Message(), message)
}
return false
}
// getCommand return a valid ordered set of arguments to pass to the driver command.
func (s Session) getCommand(ctx context.Context) ([]string, string, error) {
var session *ssm.StartSessionOutput
err := retry.Config{
ShouldRetry: func(err error) bool { return isAWSErr(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, &s.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(s.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 packer.Ui) error {
for ctx.Err() == nil {
log.Printf("ssm: Starting PortForwarding session to instance %q", *s.Input.Target)
args, sessionID, err := s.getCommand(ctx)
if sessionID != "" {
defer func() {
_, err := s.SvcClient.TerminateSession(&ssm.TerminateSessionInput{SessionId: aws.String(sessionID)})
if err != nil {
err = fmt.Errorf("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
}

View File

@ -2,17 +2,9 @@ package common
import (
"context"
"encoding/json"
"fmt"
"log"
"os/exec"
"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/common/retry"
"github.com/mitchellh/iochan"
)
const (
@ -34,212 +26,9 @@ type SSMDriver struct {
session *ssm.StartSessionOutput
sessionParams ssm.StartSessionInput
pluginCmdFunc func(context.Context) error
retryAfterTermination chan bool
}
func NewSSMDriver(config SSMDriverConfig) *SSMDriver {
d := SSMDriver{SSMDriverConfig: config}
return &d
}
// StartSession starts an interactive Systems Manager session with a remote instance via the AWS session-manager-plugin
// This ssm.StartSessionOutput returned by this function can be used for terminating the session manually. If you do
// not wish to manage the session manually calling StopSession on a instance of this driver will terminate the active session
// created from calling StartSession.
func (d *SSMDriver) StartSession(ctx context.Context, input ssm.StartSessionInput) (*ssm.StartSessionOutput, error) {
log.Printf("Starting PortForwarding session to instance %q", aws.StringValue(input.Target))
output, err := d.StartSessionWithContext(ctx, input)
if err != nil {
return nil, fmt.Errorf("error encountered in starting session for instance %q: %s", aws.StringValue(input.Target), err)
}
d.retryAfterTermination = make(chan bool, 1)
// Starts go routine that will keep listening to channels and retry the session creation/connection when needed.
// The log polling process will add data to the channels whenever a retryable error happens to the session or if it's terminated.
go func(ctx context.Context, driver *SSMDriver, input ssm.StartSessionInput) {
for {
select {
case <-ctx.Done():
return
case r, ok := <-driver.retryAfterTermination:
if !ok {
return
}
if r {
log.Printf("[DEBUG] Attempting to restablishing SSM connection")
_, _ = driver.StartSession(ctx, input)
// End this routine. Another routine will start.
return
}
}
}
}(ctx, d, input)
d.session = output
d.sessionParams = input
if d.pluginCmdFunc == nil {
d.pluginCmdFunc = d.openTunnelForSession
}
if err := d.pluginCmdFunc(ctx); err != nil {
return nil, fmt.Errorf("error encountered in starting session for instance %q: %s", aws.StringValue(input.Target), err)
}
return d.session, nil
}
func (d *SSMDriver) StartSessionWithContext(ctx context.Context, input ssm.StartSessionInput) (*ssm.StartSessionOutput, error) {
var output *ssm.StartSessionOutput
err := retry.Config{
ShouldRetry: func(err error) bool { return IsAWSErr(err, "TargetNotConnected", "") },
RetryDelay: (&retry.Backoff{InitialBackoff: 200 * time.Millisecond, MaxBackoff: 60 * time.Second, Multiplier: 2}).Linear,
}.Run(ctx, func(ctx context.Context) (err error) {
output, err = d.SvcClient.StartSessionWithContext(ctx, &input)
return err
})
return output, err
}
func (d *SSMDriver) openTunnelForSession(ctx context.Context) error {
args, err := d.Args()
if err != nil {
return fmt.Errorf("error encountered validating session details: %s", err)
}
cmd := exec.CommandContext(ctx, sessionManagerPluginName, args...)
// Let's build up our logging
stdout, err := cmd.StdoutPipe()
if err != nil {
return err
}
stderr, err := cmd.StderrPipe()
if err != nil {
return err
}
// Create the channels we'll use for data
stdoutCh := iochan.DelimReader(stdout, '\n')
stderrCh := iochan.DelimReader(stderr, '\n')
/* Loop and get all our output
This particular logger will continue to run through an entire Packer run.
The decision to continue logging is due to the fact that session-manager-plugin
doesn't give a good way of knowing if the command failed or was successful other
than looking at the logs. Seeing as the plugin is updated frequently and that the
log information is a bit sparse this logger will indefinitely relying on other
steps to fail if the tunnel is unable to be created. If successful then the user
will get more information on the tunnel connection when running in a debug mode.
*/
go func(ctx context.Context, prefix string) {
for {
select {
case <-ctx.Done():
return
case errorOut, ok := <-stderrCh:
if !ok {
stderrCh = nil
break
}
if errorOut == "" {
continue
}
log.Printf("[ERROR] %s: %s", prefix, errorOut)
case output, ok := <-stdoutCh:
if !ok {
stdoutCh = nil
break
}
if output == "" {
continue
}
log.Printf("[DEBUG] %s: %s", prefix, output)
}
if stdoutCh == nil && stderrCh == nil {
// It's possible that a remote SSM session was terminated prematurely due to a system reboot, or a termination
// on the AWS console, or that the SSMAgent service was stopped on the instance. This will try to reconnect
// until the build eventually fails or hits the ssh_timeout threshold.
log.Printf("[DEBUG] %s: %s", prefix, "active session has been terminated; stopping all log polling processes.")
// A call to StopSession will nullify any active sessions so only retry if StopSession has not be called,
// since StopSession will also close the retryAfterTermination channel
if d.session != nil {
d.retryAfterTermination <- true
}
return
}
}
}(ctx, sessionManagerPluginName)
log.Printf("[DEBUG %s] opening session tunnel to instance %q for session %q", sessionManagerPluginName,
aws.StringValue(d.sessionParams.Target),
aws.StringValue(d.session.SessionId),
)
if err := cmd.Start(); err != nil {
err = fmt.Errorf("error encountered when calling %s: %s\n", sessionManagerPluginName, err)
return err
}
return nil
}
// StopSession terminates an active Session Manager session
func (d *SSMDriver) StopSession() error {
if d.session == nil || d.session.SessionId == nil {
return fmt.Errorf("Unable to find a valid session to instance %q; skipping the termination step",
aws.StringValue(d.sessionParams.Target))
}
// Store session id before we nullify any active sessions
sid := aws.StringValue(d.session.SessionId)
// Stop retry polling process to avoid unwanted retries at this point
d.session = nil
close(d.retryAfterTermination)
_, err := d.SvcClient.TerminateSession(&ssm.TerminateSessionInput{SessionId: aws.String(sid)})
if err != nil {
err = fmt.Errorf("Error terminating SSM Session %q. Please terminate the session manually: %s", sid, err)
}
return err
}
// Args validates the driver inputs before returning an ordered set of arguments to pass to the driver command.
func (d *SSMDriver) Args() ([]string, error) {
if d.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(d.session)
if err != nil {
return nil, 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(d.sessionParams)
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),
d.Region,
sessionCommand,
d.ProfileName,
string(sessionParameters),
d.SvcEndpoint,
}
return args, nil
}

View File

@ -21,6 +21,7 @@ func (svc *MockSSMSvc) StartSessionWithContext(ctx aws.Context, input *ssm.Start
svc.StartSessionCalled = true
return MockStartSessionOutput(), svc.StartSessionError
}
func (svc *MockSSMSvc) TerminateSession(input *ssm.TerminateSessionInput) (*ssm.TerminateSessionOutput, error) {
svc.TerminateSessionCalled = true
return new(ssm.TerminateSessionOutput), svc.TerminateSessionError

View File

@ -10,6 +10,7 @@ import (
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/ec2"
"github.com/aws/aws-sdk-go/service/ssm"
pssm "github.com/hashicorp/packer/builder/amazon/common/ssm"
"github.com/hashicorp/packer/common/net"
"github.com/hashicorp/packer/helper/multistep"
"github.com/hashicorp/packer/packer"
@ -24,6 +25,7 @@ type StepCreateSSMTunnel struct {
instanceId string
PauseBeforeSSM time.Duration
driver *SSMDriver
stopSSMCommand func()
}
// Run executes the Packer build step that creates a session tunnel.
@ -73,30 +75,38 @@ func (s *StepCreateSSMTunnel) Run(ctx context.Context, state multistep.StateBag)
driver := SSMDriver{SSMDriverConfig: cfg}
s.driver = &driver
}
state.Put("sessionPort", s.LocalPortNumber)
input := s.BuildTunnelInputForInstance(s.instanceId)
_, err := s.driver.StartSession(ctx, input)
if err != nil {
err = fmt.Errorf("error encountered in establishing a tunnel %s", err)
ui.Error(err.Error())
state.Put("error", err)
return multistep.ActionHalt
}
ui.Message(fmt.Sprintf("PortForwarding session %q has been started", s.instanceId))
state.Put("sessionPort", s.LocalPortNumber)
ssmCtx, ssmCancel := context.WithCancel(ctx)
s.stopSSMCommand = ssmCancel
go func() {
err := pssm.Session{
SvcClient: s.driver.SvcClient,
Input: input,
Region: s.driver.Region,
}.Start(ssmCtx, ui)
if err != nil {
err = fmt.Errorf("error encountered in establishing a tunnel %s", err)
ui.Error(err.Error())
state.Put("error", 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) {
ui := state.Get("ui").(packer.Ui)
if !s.SSMAgentEnabled {
return
}
if err := s.driver.StopSession(); err != nil {
ui.Error(err.Error())
if s.stopSSMCommand != nil {
s.stopSSMCommand()
}
}

View File

@ -0,0 +1,18 @@
package error
import (
"strings"
"github.com/aws/aws-sdk-go/aws/awserr"
)
// Returns true if the err matches all these conditions:
// * err is of type awserr.Error
// * Error.Code() matches code
// * Error.Message() contains message
func Matches(err error, code string, message string) bool {
if err, ok := err.(awserr.Error); ok {
return err.Code() == code && strings.Contains(err.Message(), message)
}
return false
}

2
go.mod
View File

@ -93,7 +93,6 @@ require (
github.com/mitchellh/go-homedir v1.1.0
github.com/mitchellh/go-testing-interface v1.0.3 // indirect
github.com/mitchellh/go-vnc v0.0.0-20150629162542-723ed9867aed
github.com/mitchellh/gox v1.0.1 // indirect
github.com/mitchellh/iochan v1.0.0
github.com/mitchellh/mapstructure v1.2.3
github.com/mitchellh/panicwrap v1.0.0
@ -104,7 +103,6 @@ require (
github.com/nu7hatch/gouuid v0.0.0-20131221200532-179d4d0c4d8d // indirect
github.com/olekukonko/tablewriter v0.0.0-20180105111133-96aac992fc8b
github.com/oracle/oci-go-sdk v18.0.0+incompatible
github.com/outscale/osc-go v0.0.1 // indirect
github.com/outscale/osc-sdk-go/osc v0.0.0-20200722135656-d654809d0699
github.com/packer-community/winrmcp v0.0.0-20180921204643-0fd363d6159a
github.com/pierrec/lz4 v2.0.5+incompatible

11
go.sum
View File

@ -126,7 +126,6 @@ github.com/armon/go-radix v0.0.0-20180808171621-7fddfc383310/go.mod h1:ufUuZ+zHj
github.com/armon/go-radix v1.0.0 h1:F4z6KzEeeQIMeLFa97iZU6vupzoecKdU5TX24SNppXI=
github.com/armon/go-radix v1.0.0/go.mod h1:ufUuZ+zHj4x4TnLV4JWEpy2hxWSpsRywHrMgIH9cCH8=
github.com/aws/aws-sdk-go v1.15.78/go.mod h1:E3/ieXAlvM0XWO57iftYVDLLvQ824smPP3ATZkfNZeM=
github.com/aws/aws-sdk-go v1.16.22/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
github.com/aws/aws-sdk-go v1.26.3/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
github.com/aws/aws-sdk-go v1.30.8 h1:4BHbh8K3qKmcnAgToZ2LShldRF9inoqIBccpCLNCy3I=
github.com/aws/aws-sdk-go v1.30.8/go.mod h1:5zCpMtNQVjRREroY7sYe8lOMRSxkhG6MZveU8YkpAk0=
@ -377,7 +376,6 @@ github.com/hashicorp/go-uuid v1.0.1 h1:fv1ep09latC32wFoVwnqcnKJGnMSdBanPczbHAYm1
github.com/hashicorp/go-uuid v1.0.1/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
github.com/hashicorp/go-uuid v1.0.2 h1:cfejS+Tpcp13yd5nYHWDI6qVCny6wyX2Mt5SGur2IGE=
github.com/hashicorp/go-uuid v1.0.2/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
github.com/hashicorp/go-version v1.0.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
github.com/hashicorp/go-version v1.1.0 h1:bPIoEKD27tNdebFGGxxYwcL4nepeY4j1QP23PFRGzg0=
github.com/hashicorp/go-version v1.1.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
github.com/hashicorp/go-version v1.2.0 h1:3vNe/fWF5CBgRIguda1meWhsZHy3m8gCJ5wx+dIzX/E=
@ -512,8 +510,6 @@ github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7/go.mod h1:ZX
github.com/mitchellh/go-wordwrap v1.0.0 h1:6GlHJ/LTGMrIJbwgdqdl2eEH8o+Exx/0m8ir9Gns0u4=
github.com/mitchellh/go-wordwrap v1.0.0/go.mod h1:ZXFpozHsX6DPmq2I0TCekCxypsnAUbP2oI0UX1GXzOo=
github.com/mitchellh/gox v0.4.0/go.mod h1:Sd9lOJ0+aimLBi73mGofS1ycjY8lL3uZM3JPS42BGNg=
github.com/mitchellh/gox v1.0.1 h1:x0jD3dcHk9a9xPSDN6YEL4xL6Qz0dvNYm8yZqui5chI=
github.com/mitchellh/gox v1.0.1/go.mod h1:ED6BioOGXMswlXa2zxfh/xdd5QhwYliBFn9V18Ap4z4=
github.com/mitchellh/iochan v1.0.0 h1:C+X3KsSTLFVBr/tK1eYN/vs4rJcvsiLU338UhYPJWeY=
github.com/mitchellh/iochan v1.0.0/go.mod h1:JwYml1nuB7xOzsp52dPpHFffvOCDupsG0QubkSMEySY=
github.com/mitchellh/mapstructure v0.0.0-20160808181253-ca63d7c062ee/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
@ -538,9 +534,6 @@ github.com/olekukonko/tablewriter v0.0.0-20180105111133-96aac992fc8b/go.mod h1:v
github.com/opentracing/opentracing-go v1.1.0/go.mod h1:UkNAQd3GIcIGf0SeVgPpRdFStlNbqXla1AfSYxPUl2o=
github.com/oracle/oci-go-sdk v18.0.0+incompatible h1:FLV4KixsVfF3rwyVTMI6Ryp/Q+OSb9sR5TawbfjFLN4=
github.com/oracle/oci-go-sdk v18.0.0+incompatible/go.mod h1:VQb79nF8Z2cwLkLS35ukwStZIg5F66tcBccjip/j888=
github.com/outscale/osc-go v0.0.1 h1:hvBtORyu7sWSKW1norGlfIP8C7c2aegI2Vkq75SRPCE=
github.com/outscale/osc-go v0.0.1/go.mod h1:hJLmXzqU/t07qQYh90I0TqZzu9s85Zs6FMrxk3ukiFM=
github.com/outscale/osc-sdk-go v1.2.0 h1:1HKr6OMLLVW4w6KQuiQwYZjhNaVz9mNzy/W3KW+zgnA=
github.com/outscale/osc-sdk-go/osc v0.0.0-20200722135656-d654809d0699 h1:SHe9i7h5cHe+cB77fQ6lsEgIwKg3ckNU90P03CjGMnI=
github.com/outscale/osc-sdk-go/osc v0.0.0-20200722135656-d654809d0699/go.mod h1:5AqqNH1X8zCHescKVlpSHRzrat1KCKDXqZoQPe8fY3A=
github.com/packer-community/winrmcp v0.0.0-20180921204643-0fd363d6159a h1:A3QMuteviunoaY/8ex+RKFqwhcZJ/Cf3fCW3IwL2wx4=
@ -636,12 +629,8 @@ github.com/vmware/govmomi v0.23.1/go.mod h1:Y+Wq4lst78L85Ge/F8+ORXIWiKYqaro1vhAu
github.com/vmware/vmw-guestinfo v0.0.0-20170707015358-25eff159a728/go.mod h1:x9oS4Wk2s2u4tS29nEaDLdzvuHdB19CvSGJjPgkZJNk=
github.com/xanzy/go-cloudstack v0.0.0-20190526095453-42f262b63ed0 h1:NJrcIkdzq0C3I8ypAZwFE9RHtGbfp+mJvqIcoFATZuk=
github.com/xanzy/go-cloudstack v0.0.0-20190526095453-42f262b63ed0/go.mod h1:sBh287mCRwCz6zyXHMmw7sSZGPohVpnx+o+OY4M+i3A=
github.com/yandex-cloud/go-genproto v0.0.0-20200608085315-d6e7ef5ceb97 h1:DoqSUxQkBLislVgA1qkM0u7g04It4VRMidyLBH/O/as=
github.com/yandex-cloud/go-genproto v0.0.0-20200608085315-d6e7ef5ceb97/go.mod h1:HEUYX/p8966tMUHHT+TsS0hF/Ca/NYwqprC5WXSDMfE=
github.com/yandex-cloud/go-genproto v0.0.0-20200915125933-33de72a328bd h1:o4pvS7D4OErKOM6y+/q6IfOa65OaentKbEDh1ABirE8=
github.com/yandex-cloud/go-genproto v0.0.0-20200915125933-33de72a328bd/go.mod h1:HEUYX/p8966tMUHHT+TsS0hF/Ca/NYwqprC5WXSDMfE=
github.com/yandex-cloud/go-sdk v0.0.0-20200610100221-ae86895efb97 h1:8KwSw9xtQBeyeX1EpOlOjRc0JaHlh8B8GglKA6iXt08=
github.com/yandex-cloud/go-sdk v0.0.0-20200610100221-ae86895efb97/go.mod h1:3p2xVpQrHyPxV4UCKnKozt9n+g1LRENOQ33CH8rqLnY=
github.com/yandex-cloud/go-sdk v0.0.0-20200921111412-ef15ded2014c h1:LJrgyICodRAgtBvOO2eCbhDDIoaJgeLa1tGQecqW9ac=
github.com/yandex-cloud/go-sdk v0.0.0-20200921111412-ef15ded2014c/go.mod h1:Zn/U9YKH0w8n83ezLps5eB6Jftc4gSoZWxVR8hgXgoY=
github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=