User Migration Trigger Lambda Not Functioning

Question

I'm attempting to implement the example lambda from the AWS documentation  in Python. After combing through the documentation many times, it seems to me that I need to set the 'userAttributes', 'finalUserStatus', and 'messageAction' fields for the 'UserMigration_Authentication' flow and Cognito does the rest. However, after following the example and writing the following code, my lambda trigger does not migrate the user. I've verified this by going to the Cognito logs and the user does not exist. I am using AWS' HostedUI and the HostedUI returns an error upon attempted migration (The username or password you entered is invalid). I have code to migrate the user manually, however I'd like to use AWS' method.  
  
If anyone can provide insight into my errors, I would appreciate it.

```
def lookup_user(username, old_user_pool):
    # ... Lookup user in legacy user pool (old_user_pool) ...
    return user

def authenticate_user(old_user_pool, old_client_id, username, password):
   # ... Authenticate user in legacy user pool (old_user_pool) ...
    return lookup_user(username, old_user_pool)

def usermigration_authentication(event, old_user_pool, old_client_id, username, password):

user = authenticate_user(old_user_pool, old_client_id, username, password)

if not user:
        raise Exception('Bad Credentials')

event['response']['userAttributes'] = user['Attributes']
    event['response']['finalUserStatus'] = 'CONFIRMED'
    event['response']['messageAction']= "SUPPRESS"

return event

def usermigration_forgotpassword(event, old_user_pool, username):
    user = lookup_user(username, old_user_pool)
    if not user:
        raise Exception('Bad Credentials')

event['response']['userAttributes'] = user['Attributes']
    event['response']['messageAction']= "SUPPRESS"

return event

def handler(event, context):

trigger_source = event['triggerSource']
    password = event['request']['password']
    email = event['userName']
    logger.info({'message': "User email: " + email})

old_user_pool = os.environ.get('migration_user_pool')
    old_client_id = os.environ.get('old_client_id')

try:
        if trigger_source == "UserMigration_Authentication":
            event = usermigration_authentication(event, old_user_pool, old_client_id, email, password)
        elif trigger_source == "UserMigration_ForgotPassword":
            event = usermigration_forgotpassword(event, old_user_pool, email)

except Exception as err:
        logger.error({'message': {'Error attempting to migrate user': err}})

return event
```

Edited by: ansonss on Oct 19, 2020 6:17 AM

Answer

Here was my issue:  
  
I used the boto3 cognito-idp.list_users() function to obtain the user attributes of the previous user pool - wanting to automate everything. However, this call returned the attributes in the following fashion:

```
{
   'Name': name_string,
   'Value': value_string
}
```

The user migration lambda requires the attributes to be formatted in the following way:

```
{
    name_string: value_string
}
```

Simple data manipulation fixed the issue.  
  
Edited by: ansonss on Oct 20, 2020 10:23 AM

User Migration Trigger Lambda Not Functioning

Relevant content