Write custom activity data with a Lambda function after Amazon Cognito user authentication using an Amazon SDK

Run an interactive scenario at a command prompt.

// ActivityLog separates the steps of this scenario into individual functions so that
// they are simpler to read and understand.
type ActivityLog struct {
	helper       IScenarioHelper
	questioner   demotools.IQuestioner
	resources    Resources
	cognitoActor *actions.CognitoActions
}

// NewActivityLog constructs a new activity log runner.
func NewActivityLog(sdkConfig aws.Config, questioner demotools.IQuestioner, helper IScenarioHelper) ActivityLog {
	scenario := ActivityLog{
		helper:       helper,
		questioner:   questioner,
		resources:    Resources{},
		cognitoActor: &actions.CognitoActions{CognitoClient: cognitoidentityprovider.NewFromConfig(sdkConfig)},
	}
	scenario.resources.init(scenario.cognitoActor, questioner)
	return scenario
}

// AddUserToPool selects a user from the known users table and uses administrator credentials to add the user to the user pool.
func (runner *ActivityLog) AddUserToPool(userPoolId string, tableName string) (string, string) {
	log.Println("To facilitate this example, let's add a user to the user pool using administrator privileges.")
	users, err := runner.helper.GetKnownUsers(tableName)
	if err != nil {
		panic(err)
	}
	user := users.Users[0]
	log.Printf("Adding known user %v to the user pool.\n", user.UserName)
	err = runner.cognitoActor.AdminCreateUser(userPoolId, user.UserName, user.UserEmail)
	if err != nil {
		panic(err)
	}
	pwSet := false
	password := runner.questioner.AskPassword("\nEnter a password that has at least eight characters, uppercase, lowercase, numbers and symbols.\n"+
		"(the password will not display as you type):", 8)
	for !pwSet {
		log.Printf("\nSetting password for user '%v'.\n", user.UserName)
		err = runner.cognitoActor.AdminSetUserPassword(userPoolId, user.UserName, password)
		if err != nil {
			var invalidPassword *types.InvalidPasswordException
			if errors.As(err, &invalidPassword) {
				password = runner.questioner.AskPassword("\nEnter another password:", 8)
			} else {
				panic(err)
			}
		} else {
			pwSet = true
		}
	}

	log.Println(strings.Repeat("-", 88))

	return user.UserName, password
}

// AddActivityLogTrigger adds a Lambda handler as an invocation target for the PostAuthentication trigger.
func (runner *ActivityLog) AddActivityLogTrigger(userPoolId string, activityLogArn string) {
	log.Println("Let's add a Lambda function to handle the PostAuthentication trigger from Cognito.\n" +
		"This trigger happens after a user is authenticated, and lets your function take action, such as logging\n" +
		"the outcome.")
	err := runner.cognitoActor.UpdateTriggers(
		userPoolId,
		actions.TriggerInfo{Trigger: actions.PostAuthentication, HandlerArn: aws.String(activityLogArn)})
	if err != nil {
		panic(err)
	}
	runner.resources.triggers = append(runner.resources.triggers, actions.PostAuthentication)
	log.Printf("Lambda function %v added to user pool %v to handle PostAuthentication Cognito trigger.\n",
		activityLogArn, userPoolId)

	log.Println(strings.Repeat("-", 88))
}

// SignInUser signs in as the specified user.
func (runner *ActivityLog) SignInUser(clientId string, userName string, password string) {
	log.Printf("Now we'll sign in user %v and check the results in the logs and the DynamoDB table.", userName)
	runner.questioner.Ask("Press Enter when you're ready.")
	authResult, err := runner.cognitoActor.SignIn(clientId, userName, password)
	if err != nil {
		panic(err)
	}
	log.Println("Sign in successful.",
		"The PostAuthentication Lambda handler writes custom information to CloudWatch Logs.")

	runner.resources.userAccessTokens = append(runner.resources.userAccessTokens, *authResult.AccessToken)
}

// GetKnownUserLastLogin gets the login info for a user from the Amazon DynamoDB table and displays it.
func (runner *ActivityLog) GetKnownUserLastLogin(tableName string, userName string) {
	log.Println("The PostAuthentication handler also writes login data to the DynamoDB table.")
	runner.questioner.Ask("Press Enter when you're ready to continue.")
	users, err := runner.helper.GetKnownUsers(tableName)
	if err != nil {
		panic(err)
	}
	for _, user := range users.Users {
		if user.UserName == userName {
			log.Println("The last login info for the user in the known users table is:")
			log.Printf("\t%+v", *user.LastLogin)
		}
	}
	log.Println(strings.Repeat("-", 88))
}

// Run runs the scenario.
func (runner *ActivityLog) Run(stackName string) {
	defer func() {
		if r := recover(); r != nil {
			log.Println("Something went wrong with the demo.")
			runner.resources.Cleanup()
		}
	}()

	log.Println(strings.Repeat("-", 88))
	log.Printf("Welcome\n")

	log.Println(strings.Repeat("-", 88))

	stackOutputs, err := runner.helper.GetStackOutputs(stackName)
	if err != nil {
		panic(err)
	}
	runner.resources.userPoolId = stackOutputs["UserPoolId"]
	runner.helper.PopulateUserTable(stackOutputs["TableName"])
	userName, password := runner.AddUserToPool(stackOutputs["UserPoolId"], stackOutputs["TableName"])

	runner.AddActivityLogTrigger(stackOutputs["UserPoolId"], stackOutputs["ActivityLogFunctionArn"])
	runner.SignInUser(stackOutputs["UserPoolClientId"], userName, password)
	runner.helper.ListRecentLogEvents(stackOutputs["ActivityLogFunction"])
	runner.GetKnownUserLastLogin(stackOutputs["TableName"], userName)

	runner.resources.Cleanup()

	log.Println(strings.Repeat("-", 88))
	log.Println("Thanks for watching!")
	log.Println(strings.Repeat("-", 88))
}

Handle the PostAuthentication trigger with a Lambda function.

const TABLE_NAME = "TABLE_NAME"

// LoginInfo defines structured login data that can be marshalled to a DynamoDB format.
type LoginInfo struct {
	UserPoolId string `dynamodbav:"UserPoolId"`
	ClientId   string `dynamodbav:"ClientId"`
	Time       string `dynamodbav:"Time"`
}

// UserInfo defines structured user data that can be marshalled to a DynamoDB format.
type UserInfo struct {
	UserName  string    `dynamodbav:"UserName"`
	UserEmail string    `dynamodbav:"UserEmail"`
	LastLogin LoginInfo `dynamodbav:"LastLogin"`
}

// GetKey marshals the user email value to a DynamoDB key format.
func (user UserInfo) GetKey() map[string]dynamodbtypes.AttributeValue {
	userEmail, err := attributevalue.Marshal(user.UserEmail)
	if err != nil {
		panic(err)
	}
	return map[string]dynamodbtypes.AttributeValue{"UserEmail": userEmail}
}

type handler struct {
	dynamoClient *dynamodb.Client
}

// HandleRequest handles the PostAuthentication event by writing custom data to the logs and
// to an Amazon DynamoDB table.
func (h *handler) HandleRequest(ctx context.Context, event events.CognitoEventUserPoolsPostAuthentication) (events.CognitoEventUserPoolsPostAuthentication, error) {
	log.Printf("Received post authentication trigger from %v for user '%v'", event.TriggerSource, event.UserName)
	tableName := os.Getenv(TABLE_NAME)
	user := UserInfo{
		UserName:  event.UserName,
		UserEmail: event.Request.UserAttributes["email"],
		LastLogin: LoginInfo{
			UserPoolId: event.UserPoolID,
			ClientId:   event.CallerContext.ClientID,
			Time:       time.Now().Format(time.UnixDate),
		},
	}
	// Write to CloudWatch Logs.
	fmt.Printf("%#v", user)

	// Also write to an external system. This examples uses DynamoDB to demonstrate.
	userMap, err := attributevalue.MarshalMap(user)
	if err != nil {
		log.Printf("Couldn't marshal to DynamoDB map. Here's why: %v\n", err)
	} else if len(userMap) == 0 {
		log.Printf("User info marshaled to an empty map.")
	} else {
		_, err := h.dynamoClient.PutItem(ctx, &dynamodb.PutItemInput{
			Item:      userMap,
			TableName: aws.String(tableName),
		})
		if err != nil {
			log.Printf("Couldn't write to DynamoDB. Here's why: %v\n", err)
		} else {
			log.Printf("Wrote user info to DynamoDB table %v.\n", tableName)
		}
	}

	return event, nil
}

func main() {
	sdkConfig, err := config.LoadDefaultConfig(context.TODO())
	if err != nil {
		log.Panicln(err)
	}
	h := handler{
		dynamoClient: dynamodb.NewFromConfig(sdkConfig),
	}
	lambda.Start(h.HandleRequest)
}

Create a struct that performs common tasks.

// IScenarioHelper defines common functions used by the workflows in this example.
type IScenarioHelper interface {
	Pause(secs int)
	GetStackOutputs(stackName string) (actions.StackOutputs, error)
	PopulateUserTable(tableName string)
	GetKnownUsers(tableName string) (actions.UserList, error)
	AddKnownUser(tableName string, user actions.User)
	ListRecentLogEvents(functionName string)
}

// ScenarioHelper contains AWS wrapper structs used by the workflows in this example.
type ScenarioHelper struct {
	questioner  demotools.IQuestioner
	dynamoActor *actions.DynamoActions
	cfnActor    *actions.CloudFormationActions
	cwlActor    *actions.CloudWatchLogsActions
	isTestRun   bool
}

// NewScenarioHelper constructs a new scenario helper.
func NewScenarioHelper(sdkConfig aws.Config, questioner demotools.IQuestioner) ScenarioHelper {
	scenario := ScenarioHelper{
		questioner:  questioner,
		dynamoActor: &actions.DynamoActions{DynamoClient: dynamodb.NewFromConfig(sdkConfig)},
		cfnActor:    &actions.CloudFormationActions{CfnClient: cloudformation.NewFromConfig(sdkConfig)},
		cwlActor:    &actions.CloudWatchLogsActions{CwlClient: cloudwatchlogs.NewFromConfig(sdkConfig)},
	}
	return scenario
}

// Pause waits for the specified number of seconds.
func (helper ScenarioHelper) Pause(secs int) {
	if !helper.isTestRun {
		time.Sleep(time.Duration(secs) * time.Second)
	}
}

// GetStackOutputs gets the outputs from the specified CloudFormation stack in a structured format.
func (helper ScenarioHelper) GetStackOutputs(stackName string) (actions.StackOutputs, error) {
	return helper.cfnActor.GetOutputs(stackName), nil
}

// PopulateUserTable fills the known user table with example data.
func (helper ScenarioHelper) PopulateUserTable(tableName string) {
	log.Printf("First, let's add some users to the DynamoDB %v table we'll use for this example.\n", tableName)
	err := helper.dynamoActor.PopulateTable(tableName)
	if err != nil {
		panic(err)
	}
}

// GetKnownUsers gets the users from the known users table in a structured format.
func (helper ScenarioHelper) GetKnownUsers(tableName string) (actions.UserList, error) {
	knownUsers, err := helper.dynamoActor.Scan(tableName)
	if err != nil {
		log.Printf("Couldn't get known users from table %v. Here's why: %v\n", tableName, err)
	}
	return knownUsers, err
}

// AddKnownUser adds a user to the known users table.
func (helper ScenarioHelper) AddKnownUser(tableName string, user actions.User) {
	log.Printf("Adding user '%v' with email '%v' to the DynamoDB known users table...\n",
		user.UserName, user.UserEmail)
	err := helper.dynamoActor.AddUser(tableName, user)
	if err != nil {
		panic(err)
	}
}

// ListRecentLogEvents gets the most recent log stream and events for the specified Lambda function and displays them.
func (helper ScenarioHelper) ListRecentLogEvents(functionName string) {
	log.Println("Waiting a few seconds to let Lambda write to CloudWatch Logs...")
	helper.Pause(10)
	log.Println("Okay, let's check the logs to find what's happened recently with your Lambda function.")
	logStream, err := helper.cwlActor.GetLatestLogStream(functionName)
	if err != nil {
		panic(err)
	}
	log.Printf("Getting some recent events from log stream %v\n", *logStream.LogStreamName)
	events, err := helper.cwlActor.GetLogEvents(functionName, *logStream.LogStreamName, 10)
	if err != nil {
		panic(err)
	}
	for _, event := range events {
		log.Printf("\t%v", *event.Message)
	}
	log.Println(strings.Repeat("-", 88))
}

Create a struct that wraps Amazon Cognito actions.

type CognitoActions struct {
	CognitoClient *cognitoidentityprovider.Client
}



// Trigger and TriggerInfo define typed data for updating an Amazon Cognito trigger.
type Trigger int

const (
	PreSignUp Trigger = iota
	UserMigration
	PostAuthentication
)

type TriggerInfo struct {
	Trigger    Trigger
	HandlerArn *string
}

// UpdateTriggers adds or removes Lambda triggers for a user pool. When a trigger is specified with a `nil` value,
// it is removed from the user pool.
func (actor CognitoActions) UpdateTriggers(userPoolId string, triggers ...TriggerInfo) error {
	output, err := actor.CognitoClient.DescribeUserPool(context.TODO(), &cognitoidentityprovider.DescribeUserPoolInput{
		UserPoolId: aws.String(userPoolId),
	})
	if err != nil {
		log.Printf("Couldn't get info about user pool %v. Here's why: %v\n", userPoolId, err)
		return err
	}
	lambdaConfig := output.UserPool.LambdaConfig
	for _, trigger := range triggers {
		switch trigger.Trigger {
		case PreSignUp:
			lambdaConfig.PreSignUp = trigger.HandlerArn
		case UserMigration:
			lambdaConfig.UserMigration = trigger.HandlerArn
		case PostAuthentication:
			lambdaConfig.PostAuthentication = trigger.HandlerArn
		}
	}
	_, err = actor.CognitoClient.UpdateUserPool(context.TODO(), &cognitoidentityprovider.UpdateUserPoolInput{
		UserPoolId:   aws.String(userPoolId),
		LambdaConfig: lambdaConfig,
	})
	if err != nil {
		log.Printf("Couldn't update user pool %v. Here's why: %v\n", userPoolId, err)
	}
	return err
}



// SignUp signs up a user with Amazon Cognito.
func (actor CognitoActions) SignUp(clientId string, userName string, password string, userEmail string) (bool, error) {
	confirmed := false
	output, err := actor.CognitoClient.SignUp(context.TODO(), &cognitoidentityprovider.SignUpInput{
		ClientId: aws.String(clientId),
		Password: aws.String(password),
		Username: aws.String(userName),
		UserAttributes: []types.AttributeType{
			{Name: aws.String("email"), Value: aws.String(userEmail)},
		},
	})
	if err != nil {
		var invalidPassword *types.InvalidPasswordException
		if errors.As(err, &invalidPassword) {
			log.Println(*invalidPassword.Message)
		} else {
			log.Printf("Couldn't sign up user %v. Here's why: %v\n", userName, err)
		}
	} else {
		confirmed = output.UserConfirmed
	}
	return confirmed, err
}



// SignIn signs in a user to Amazon Cognito using a username and password authentication flow.
func (actor CognitoActions) SignIn(clientId string, userName string, password string) (*types.AuthenticationResultType, error) {
	var authResult *types.AuthenticationResultType
	output, err := actor.CognitoClient.InitiateAuth(context.TODO(), &cognitoidentityprovider.InitiateAuthInput{
		AuthFlow:       "USER_PASSWORD_AUTH",
		ClientId:       aws.String(clientId),
		AuthParameters: map[string]string{"USERNAME": userName, "PASSWORD": password},
	})
	if err != nil {
		var resetRequired *types.PasswordResetRequiredException
		if errors.As(err, &resetRequired) {
			log.Println(*resetRequired.Message)
		} else {
			log.Printf("Couldn't sign in user %v. Here's why: %v\n", userName, err)
		}
	} else {
		authResult = output.AuthenticationResult
	}
	return authResult, err
}



// ForgotPassword starts a password recovery flow for a user. This flow typically sends a confirmation code
// to the user's configured notification destination, such as email.
func (actor CognitoActions) ForgotPassword(clientId string, userName string) (*types.CodeDeliveryDetailsType, error) {
	output, err := actor.CognitoClient.ForgotPassword(context.TODO(), &cognitoidentityprovider.ForgotPasswordInput{
		ClientId: aws.String(clientId),
		Username: aws.String(userName),
	})
	if err != nil {
		log.Printf("Couldn't start password reset for user '%v'. Here;s why: %v\n", userName, err)
	}
	return output.CodeDeliveryDetails, err
}



// ConfirmForgotPassword confirms a user with a confirmation code and a new password.
func (actor CognitoActions) ConfirmForgotPassword(clientId string, code string, userName string, password string) error {
	_, err := actor.CognitoClient.ConfirmForgotPassword(context.TODO(), &cognitoidentityprovider.ConfirmForgotPasswordInput{
		ClientId:         aws.String(clientId),
		ConfirmationCode: aws.String(code),
		Password:         aws.String(password),
		Username:         aws.String(userName),
	})
	if err != nil {
		var invalidPassword *types.InvalidPasswordException
		if errors.As(err, &invalidPassword) {
			log.Println(*invalidPassword.Message)
		} else {
			log.Printf("Couldn't confirm user %v. Here's why: %v", userName, err)
		}
	}
	return err
}



// DeleteUser removes a user from the user pool.
func (actor CognitoActions) DeleteUser(userAccessToken string) error {
	_, err := actor.CognitoClient.DeleteUser(context.TODO(), &cognitoidentityprovider.DeleteUserInput{
		AccessToken: aws.String(userAccessToken),
	})
	if err != nil {
		log.Printf("Couldn't delete user. Here's why: %v\n", err)
	}
	return err
}



// AdminCreateUser uses administrator credentials to add a user to a user pool. This method leaves the user
// in a state that requires they enter a new password next time they sign in.
func (actor CognitoActions) AdminCreateUser(userPoolId string, userName string, userEmail string) error {
	_, err := actor.CognitoClient.AdminCreateUser(context.TODO(), &cognitoidentityprovider.AdminCreateUserInput{
		UserPoolId:     aws.String(userPoolId),
		Username:       aws.String(userName),
		MessageAction:  types.MessageActionTypeSuppress,
		UserAttributes: []types.AttributeType{{Name: aws.String("email"), Value: aws.String(userEmail)}},
	})
	if err != nil {
		var userExists *types.UsernameExistsException
		if errors.As(err, &userExists) {
			log.Printf("User %v already exists in the user pool.", userName)
			err = nil
		} else {
			log.Printf("Couldn't create user %v. Here's why: %v\n", userName, err)
		}
	}
	return err
}



// AdminSetUserPassword uses administrator credentials to set a password for a user without requiring a
// temporary password.
func (actor CognitoActions) AdminSetUserPassword(userPoolId string, userName string, password string) error {
	_, err := actor.CognitoClient.AdminSetUserPassword(context.TODO(), &cognitoidentityprovider.AdminSetUserPasswordInput{
		Password:   aws.String(password),
		UserPoolId: aws.String(userPoolId),
		Username:   aws.String(userName),
		Permanent:  true,
	})
	if err != nil {
		var invalidPassword *types.InvalidPasswordException
		if errors.As(err, &invalidPassword) {
			log.Println(*invalidPassword.Message)
		} else {
			log.Printf("Couldn't set password for user %v. Here's why: %v\n", userName, err)
		}
	}
	return err
}

Create a struct that wraps DynamoDB actions.

// DynamoActions encapsulates the Amazon Simple Notification Service (Amazon SNS) actions
// used in the examples.
type DynamoActions struct {
	DynamoClient *dynamodb.Client
}

// User defines structured user data.
type User struct {
	UserName  string
	UserEmail string
	LastLogin *LoginInfo `dynamodbav:",omitempty"`
}

// LoginInfo defines structured custom login data.
type LoginInfo struct {
	UserPoolId string
	ClientId   string
	Time       string
}

// UserList defines a list of users.
type UserList struct {
	Users []User
}

// UserNameList returns the usernames contained in a UserList as a list of strings.
func (users *UserList) UserNameList() []string {
	names := make([]string, len(users.Users))
	for i := 0; i < len(users.Users); i++ {
		names[i] = users.Users[i].UserName
	}
	return names
}

// PopulateTable adds a set of test users to the table.
func (actor DynamoActions) PopulateTable(tableName string) error {
	var err error
	var item map[string]types.AttributeValue
	var writeReqs []types.WriteRequest
	for i := 1; i < 4; i++ {
		item, err = attributevalue.MarshalMap(User{UserName: fmt.Sprintf("test_user_%v", i), UserEmail: fmt.Sprintf("test_email_%v@example.com", i)})
		if err != nil {
			log.Printf("Couldn't marshall user into DynamoDB format. Here's why: %v\n", err)
			return err
		}
		writeReqs = append(writeReqs, types.WriteRequest{PutRequest: &types.PutRequest{Item: item}})
	}
	_, err = actor.DynamoClient.BatchWriteItem(context.TODO(), &dynamodb.BatchWriteItemInput{
		RequestItems: map[string][]types.WriteRequest{tableName: writeReqs},
	})
	if err != nil {
		log.Printf("Couldn't populate table %v with users. Here's why: %v\n", tableName, err)
	}
	return err
}

// Scan scans the table for all items.
func (actor DynamoActions) Scan(tableName string) (UserList, error) {
	var userList UserList
	output, err := actor.DynamoClient.Scan(context.TODO(), &dynamodb.ScanInput{
		TableName: aws.String(tableName),
	})
	if err != nil {
		log.Printf("Couldn't scan table %v for items. Here's why: %v\n", tableName, err)
	} else {
		err = attributevalue.UnmarshalListOfMaps(output.Items, &userList.Users)
		if err != nil {
			log.Printf("Couldn't unmarshal items into users. Here's why: %v\n", err)
		}
	}
	return userList, err
}

// AddUser adds a user item to a table.
func (actor DynamoActions) AddUser(tableName string, user User) error {
	userItem, err := attributevalue.MarshalMap(user)
	if err != nil {
		log.Printf("Couldn't marshall user to item. Here's why: %v\n", err)
	}
	_, err = actor.DynamoClient.PutItem(context.TODO(), &dynamodb.PutItemInput{
		Item:      userItem,
		TableName: aws.String(tableName),
	})
	if err != nil {
		log.Printf("Couldn't put item in table %v. Here's why: %v", tableName, err)
	}
	return err
}

Create a struct that wraps CloudWatch Logs actions.

type CloudWatchLogsActions struct {
	CwlClient *cloudwatchlogs.Client
}

// GetLatestLogStream gets the most recent log stream for a Lambda function.
func (actor CloudWatchLogsActions) GetLatestLogStream(functionName string) (types.LogStream, error) {
	var logStream types.LogStream
	logGroupName := fmt.Sprintf("/aws/lambda/%s", functionName)
	output, err := actor.CwlClient.DescribeLogStreams(context.TODO(), &cloudwatchlogs.DescribeLogStreamsInput{
		Descending:   aws.Bool(true),
		Limit:        aws.Int32(1),
		LogGroupName: aws.String(logGroupName),
		OrderBy:      types.OrderByLastEventTime,
	})
	if err != nil {
		log.Printf("Couldn't get log streams for log group %v. Here's why: %v\n", logGroupName, err)
	} else {
		logStream = output.LogStreams[0]
	}
	return logStream, err
}

// GetLogEvents gets the most recent eventCount events from the specified log stream.
func (actor CloudWatchLogsActions) GetLogEvents(functionName string, logStreamName string, eventCount int32) (
	[]types.OutputLogEvent, error) {
	var events []types.OutputLogEvent
	logGroupName := fmt.Sprintf("/aws/lambda/%s", functionName)
	output, err := actor.CwlClient.GetLogEvents(context.TODO(), &cloudwatchlogs.GetLogEventsInput{
		LogStreamName: aws.String(logStreamName),
		Limit:         aws.Int32(eventCount),
		LogGroupName:  aws.String(logGroupName),
	})
	if err != nil {
		log.Printf("Couldn't get log event for log stream %v. Here's why: %v\n", logStreamName, err)
	} else {
		events = output.Events
	}
	return events, err
}

Create a struct that wraps Amazon CloudFormation actions.

// StackOutputs defines a map of outputs from a specific stack.
type StackOutputs map[string]string

type CloudFormationActions struct {
	CfnClient *cloudformation.Client
}

// GetOutputs gets the outputs from a CloudFormation stack and puts them into a structured format.
func (actor CloudFormationActions) GetOutputs(stackName string) StackOutputs {
	output, err := actor.CfnClient.DescribeStacks(context.TODO(), &cloudformation.DescribeStacksInput{
		StackName: aws.String(stackName),
	})
	if err != nil || len(output.Stacks) == 0 {
		log.Panicf("Couldn't find a CloudFormation stack named %v. Here's why: %v\n", stackName, err)
	}
	stackOutputs := StackOutputs{}
	for _, out := range output.Stacks[0].Outputs {
		stackOutputs[*out.OutputKey] = *out.OutputValue
	}
	return stackOutputs
}

Clean up resources.

// Resources keeps track of AWS resources created during an example and handles
// cleanup when the example finishes.
type Resources struct {
	userPoolId       string
	userAccessTokens []string
	triggers         []actions.Trigger

	cognitoActor *actions.CognitoActions
	questioner   demotools.IQuestioner
}

func (resources *Resources) init(cognitoActor *actions.CognitoActions, questioner demotools.IQuestioner) {
	resources.userAccessTokens = []string{}
	resources.triggers = []actions.Trigger{}
	resources.cognitoActor = cognitoActor
	resources.questioner = questioner
}

// Cleanup deletes all AWS resources created during an example.
func (resources *Resources) Cleanup() {
	defer func() {
		if r := recover(); r != nil {
			log.Printf("Something went wrong during cleanup.\n%v\n", r)
			log.Println("Use the AWS Management Console to remove any remaining resources \n" +
				"that were created for this scenario.")
		}
	}()

	wantDelete := resources.questioner.AskBool("Do you want to remove all of the AWS resources that were created "+
		"during this demo (y/n)?", "y")
	if wantDelete {
		for _, accessToken := range resources.userAccessTokens {
			err := resources.cognitoActor.DeleteUser(accessToken)
			if err != nil {
				log.Println("Couldn't delete user during cleanup.")
				panic(err)
			}
			log.Println("Deleted user.")
		}
		triggerList := make([]actions.TriggerInfo, len(resources.triggers))
		for i := 0; i < len(resources.triggers); i++ {
			triggerList[i] = actions.TriggerInfo{Trigger: resources.triggers[i], HandlerArn: nil}
		}
		err := resources.cognitoActor.UpdateTriggers(resources.userPoolId, triggerList...)
		if err != nil {
			log.Println("Couldn't update Cognito triggers during cleanup.")
			panic(err)
		}
		log.Println("Removed Cognito triggers from user pool.")
	} else {
		log.Println("Be sure to remove resources when you're done with them to avoid unexpected charges!")
	}
}