Develop Reference

Django channels - unable to subscribe to groups

I'm attempting to send consumers.py information to display on the client end outside of consumers.py.
I've referenced Send message using Django Channels from outside Consumer class this previous question, but the sub process .group_send or .group_add don't seem to exist, so I feel it's possible I'm missing something very easy.
Consumers.py
from channels.generic.websocket import WebsocketConsumer
from asgiref.sync import async_to_sync
class WSConsumer(WebsocketConsumer):
def connect(self):
async_to_sync(self.channel_layer.group_add)("appDel", self.channel_name)
self.accept()
self.render()
appAlarm.py
def appFunc(csvUpload):
#csvUpload=pd.read_csv(request.FILES['filename'])
csvFile = pd.DataFrame(csvUpload)
colUsernames = csvFile.usernames
print(colUsernames)
channel_layer = get_channel_layer()
for user in colUsernames:
req = r.get('https://reqres.in/api/users/2')
print(req)
t = req.json()
data = t['data']['email']
print(user + " " + data)
message = user + " " + data
async_to_sync(channel_layer.group_send)(
'appDel',
{'type': 'render', 'message': message}
)
It's throwing this error:
async_to_sync(channel_layer.group_send)(
AttributeError: 'NoneType' object has no attribute 'group_send'
and will throw the same error for group_add when stripping it back more to figure out what's going on, but per the documentation HERE I feel like this should be working.

To anyone looking at this in the future, I was not able to use redis or even memurai in Windows OS due to cost. I ended up using server side events (SSE), specifically django-eventstream, and so far it's worked great as I didn't need the client to interact with the server, for a chat application this would not work.
Eventstream creates an endpoint at /events/ the client can connect to and receive a streaming http response.
Sending data from externalFunc.py:
send_event('test', 'message', {'text': 'Hello World'})
Event listener in HTML page:
var es = new ReconnectingEventSource('/events/');
es.addEventListener('message', function (e) {
console.log(e.data);
var source = new EventSource("/events/")
var para = document.createElement("P");
const obj = JSON.parse(event.data)
para.innerText = obj.text;
document.body.appendChild(para)
}, false);
es.addEventListener('stream-reset', function (e) {
}, false);

AttributeError: 'ec2.ServiceResource' object has no attribute 'send_command'

I have tried to create user credential in AWS EC2 Windows Instance using Boto3 AWS-RunPowerShellScript. But when i trying to run this below code, getting error "AttributeError: 'ec2.ServiceResource' object has no attribute 'send_command'".
import boto3
import os
import subprocess
ssm_client = boto3.resource('ec2',aws_access_key_id='xxxxxx',aws_secret_access_key='yyyyy', region_name='us-west-2')
session = boto3.Session (profile_name='exampleaws')
response = ssm_client.send_command(
InstanceIds=[
"i-xxxxxx" # use instance id on which you want to execute, even multiple is allowd
],
DocumentName="AWS-RunPowerShellScript",
Parameters={
'commands':[
'New-LocalUser "Latchu" -Password "ABCD123" -FullName "LakshmiNarayanan" -Description "User-Details'
]
},
)
command_id = response['Command']['CommandId']
output = ssm_client.get_command_invocation(
CommandId=command_id,
InstanceId='i-xxxxxx',
)
print(output)```

Your ssm_client is incorrect as send_command is property of ssm, not ec2. Thus, it should be:
ssm_client = boto3.client('ssm', aws_access_key_id='xxxxxx', aws_secret_access_key='yyyyy', region_name='us-west-2')
Also your session is not used at all. There still could be other errors which are not apparent yet.

Use iot_v1 in a GCP Cloud Function

I'm attempting to write a GCP Cloud Function in Python that calls the API for creating an IoT device. The initial challenge seems to be getting the appropriate module (specifically iot_v1) loaded within Cloud Functions so that it can make the call.
Example Python code from Google is located at https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/iot/api-client/manager/manager.py. The specific call desired is shown in "create_es_device". Trying to repurpose that into a Cloud Function (code below) errors out with "ImportError: cannot import name 'iot_v1' from 'google.cloud' (unknown location)"
Any thoughts?
import base64
import logging
import json
import datetime
from google.auth import compute_engine
from apiclient import discovery
from google.cloud import iot_v1
def handle_notification(event, context):
#Triggered from a message on a Cloud Pub/Sub topic.
#Args:
# event (dict): Event payload.
# context (google.cloud.functions.Context): Metadata for the event.
#
pubsub_message = base64.b64decode(event['data']).decode('utf-8')
logging.info('New device registration info: {}'.format(pubsub_message))
certData = json.loads(pubsub_message)['certs']
deviceID = certData['device-id']
certKey = certData['certificate']
projectID = certData['project-id']
cloudRegion = certData['cloud-region']
registryID = certData['registry-id']
newDevice = create_device(projectID, cloudRegion, registryID, deviceID, certKey)
logging.info('New device: {}'.format(newDevice))
def create_device(project_id, cloud_region, registry_id, device_id, public_key):
# from https://cloud.google.com/iot/docs/how-tos/devices#api_1
client = iot_v1.DeviceManagerClient()
parent = client.registry_path(project_id, cloud_region, registry_id)
# Note: You can have multiple credentials associated with a device.
device_template = {
#'id': device_id,
'id' : 'testing_device',
'credentials': [{
'public_key': {
'format': 'ES256_PEM',
'key': public_key
}
}]
}
return client.create_device(parent, device_template)

You need to have the google-cloud-iot project listed in your requirements.txt file.
See https://github.com/GoogleCloudPlatform/python-docs-samples/blob/master/iot/api-client/manager/requirements.txt

AttributeError: 'EC2' object has no attribute 'tag_resources'

I run following code and get error:
#!python -u
from boto3 import client
def is_tags():
response = client('ec2', 'us-east-1').tag_resources(
ResourceARNList=[
'arn:aws:ec2:us-east-1::image/ami-55ef662f'
],
Tags=[
{
'Key': 'Name',
'Value': 'john',
},
],
)
if __name__ == '__main__':
is_tags()
It is throwing the following error:
AttributeError: 'EC2' object has no attribute 'tag_resources'
What am I doing wrong?

You are using the library incorrectly, the client object has no attribute called tag_resources, due to which the call to it is failing.
You can refer the correct usage from the boto3 documentation for Tag in EC2:
import boto3
ec2 = boto3.resource('ec2', 'us-east-1')
tag = ec2.Tag('resource_id','key','value')
EDIT: I am not sure if there is a single API for tagging multiple type of resources that consistently works. You seem to be following this API, in which case, you have to define your client correctly, like:
client = boto3.client('resourcegroupstaggingapi', 'us-east-1')

How to create a SECRET_HASH for AWS Cognito using boto3?

I want to create/calculate a SECRET_HASH for AWS Cognito using boto3 and python. This will be incorporated in to my fork of warrant.
I configured my cognito app client to use an app client secret. However, this broke the following code.
def renew_access_token(self):
"""
Sets a new access token on the User using the refresh token.
NOTE:
Does not work if "App client secret" is enabled. 'SECRET_HASH' is needed in AuthParameters.
'SECRET_HASH' requires HMAC calculations.
Does not work if "Device Tracking" is turned on.
https://stackoverflow.com/a/40875783/1783439
'DEVICE_KEY' is needed in AuthParameters. See AuthParameters section.
https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_InitiateAuth.html
"""
refresh_response = self.client.initiate_auth(
ClientId=self.client_id,
AuthFlow='REFRESH_TOKEN',
AuthParameters={
'REFRESH_TOKEN': self.refresh_token
# 'SECRET_HASH': How to generate this?
},
)
self._set_attributes(
refresh_response,
{
'access_token': refresh_response['AuthenticationResult']['AccessToken'],
'id_token': refresh_response['AuthenticationResult']['IdToken'],
'token_type': refresh_response['AuthenticationResult']['TokenType']
}
)
When I run this I receive the following exception:
botocore.errorfactory.NotAuthorizedException:
An error occurred (NotAuthorizedException) when calling the InitiateAuth operation:
Unable to verify secret hash for client <client id echoed here>.
This answer informed me that a SECRET_HASH is required to use the cognito client secret.
The aws API reference docs AuthParameters section states the following:
For REFRESH_TOKEN_AUTH/REFRESH_TOKEN: USERNAME (required), SECRET_HASH
(required if the app client is configured with a client secret),
REFRESH_TOKEN (required), DEVICE_KEY
The boto3 docs state that a SECRET_HASH is
A keyed-hash message authentication code (HMAC) calculated using the
secret key of a user pool client and username plus the client ID in
the message.
The docs explain what is needed, but not how to achieve this.

The below get_secret_hash method is a solution that I wrote in Python for a Cognito User Pool implementation, with example usage:
import boto3
import botocore
import hmac
import hashlib
import base64
class Cognito:
client_id = app.config.get('AWS_CLIENT_ID')
user_pool_id = app.config.get('AWS_USER_POOL_ID')
identity_pool_id = app.config.get('AWS_IDENTITY_POOL_ID')
client_secret = app.config.get('AWS_APP_CLIENT_SECRET')
# Public Keys used to verify tokens returned by Cognito:
# http://docs.aws.amazon.com/cognito/latest/developerguide/amazon-cognito-user-pools-using-tokens-with-identity-providers.html#amazon-cognito-identity-user-pools-using-id-and-access-tokens-in-web-api
id_token_public_key = app.config.get('JWT_ID_TOKEN_PUB_KEY')
access_token_public_key = app.config.get('JWT_ACCESS_TOKEN_PUB_KEY')
def __get_client(self):
return boto3.client('cognito-idp')
def get_secret_hash(self, username):
# A keyed-hash message authentication code (HMAC) calculated using
# the secret key of a user pool client and username plus the client
# ID in the message.
message = username + self.client_id
dig = hmac.new(self.client_secret, msg=message.encode('UTF-8'),
digestmod=hashlib.sha256).digest()
return base64.b64encode(dig).decode()
# REQUIRES that `ADMIN_NO_SRP_AUTH` be enabled on Client App for User Pool
def login_user(self, username_or_alias, password):
try:
return self.__get_client().admin_initiate_auth(
UserPoolId=self.user_pool_id,
ClientId=self.client_id,
AuthFlow='ADMIN_NO_SRP_AUTH',
AuthParameters={
'USERNAME': username_or_alias,
'PASSWORD': password,
'SECRET_HASH': self.get_secret_hash(username_or_alias)
}
)
except botocore.exceptions.ClientError as e:
return e.response

I also got a TypeError when I tried the above solution. Here is the solution that worked for me:
import hmac
import hashlib
import base64
# Function used to calculate SecretHash value for a given client
def calculateSecretHash(client_id, client_secret, username):
key = bytes(client_secret, 'utf-8')
message = bytes(f'{username}{client_id}', 'utf-8')
return base64.b64encode(hmac.new(key, message, digestmod=hashlib.sha256).digest()).decode()
# Usage example
calculateSecretHash(client_id, client_secret, username)