How to get messages from googles Pub/Sub sytsem by using the current pubsub subsciber - python-3.x

Question

I need to receive published messages from googles Pub/Sub system by using a python based subscriber.
For this I did the following steps:
On the web console I created a project, a registry, a telemetry topic, a device and attached a subscription topic to the telemtry topic
A the Moment my code can publish messages over the mqtt bridge and also the publish functionality of the pubsub library
I can pull this messages over the terminal by using the following cmd:
gcloud pubsub subscriptions pull --auto-ack projects/{project_id}/subscriptions/{subscription_topic}
In the following you see the important snippet of my code. It is based on the git-examples but some functions do not seem to exist anymore in version 0.39.1 of the google-cloud-pubsub package. One example is the subscriber.subscription_path() method.
def receive_messages(subscription_path, service_account_json):
import time
from google.cloud import pubsub_v1
subscriber = pubsub_v1.SubscriberClient(credentials=service_account_json)
#subscription_path = subscriber.subscription_path(
# project_id, subscription_name)
def callback(message):
print('Received message: {}'.format(message))
message.ack()
subscriber.subscribe(subscription_path, callback=callback)
print('Listening for messages on {}'.format(subscription_path))
while True:
time.sleep(60)
When I run this function, countless threads are started in the background bit by bit, but none of them seem to ever quit or start the callback function.
I hopefully installed all requirements:
pip3 freeze
asn1crypto==0.24.0
cachetools==3.0.0
certifi==2018.11.29
cffi==1.11.5
chardet==3.0.4
cryptography==2.4.2
google-api-core==1.7.0
google-api-python-client==1.7.5
google-auth==1.6.2
google-auth-httplib2==0.0.3
google-auth-oauthlib==0.2.0
google-cloud-bigquery==1.8.1
google-cloud-core==0.29.1
google-cloud-datastore==1.7.3
google-cloud-monitoring==0.31.1
google-cloud-pubsub==0.39.1
google-resumable-media==0.3.2
googleapis-common-protos==1.5.6
grpc-google-iam-v1==0.11.4
grpcio==1.17.1
httplib2==0.12.0
idna==2.8
keyring==10.1
keyrings.alt==1.3
oauthlib==3.0.0
paho-mqtt==1.4.0
protobuf==3.6.1
pyasn1==0.4.5
pyasn1-modules==0.2.3
pycparser==2.19
pycrypto==2.6.1
pycurl==7.43.0
pygobject==3.22.0
PyJWT==1.6.4
python-apt==1.4.0b3
pytz==2018.9
pyxdg==0.25
redis==3.0.1
requests==2.21.0
requests-oauthlib==1.2.0
RPi.GPIO==0.6.5
rsa==4.0
SecretStorage==2.3.1
six==1.12.0
unattended-upgrades==0.1
uritemplate==3.0.0
urllib3==1.24.1
virtualenv==16.2.0
I run that code on debian aswell on windows 10 and updated the gcloud:
gcloud components update
For the past week, I've been trying different solutions out of the way or starting the seemingly obsolete google examples. Also, the documentation, which seems even older than the code examples did not help with. So I hope someone here can help me to finally receive python-based client messages via the Pub/Sub-Sytsem.
I hope I could provide the most important information and thank you in advance for your effort to help me.

Answer 1

The examples maintained on the python documentation site here should be up to date. Make sure that you've followed all the steps in the "In order to use this library, you first need to go through the following steps" section before running any code. In particular, you may not have properly set up authentication, I don't believe you should be passing the credentials path manually.

Answer 2

def callback(message: pubsub_v1.subscriber.message.Message) -> None:
print(f"Received {message}.")
message.ack()
streaming_pull_future = subscriber.subscribe(subscription_path,
callback=callback)
print(f"Listening for messages on {subscription_path}..\n")
try:
streaming_pull_future.result(timeout=timeout)
except TimeoutError:
streaming_pull_future.cancel() # Trigger the shutdown.
streaming_pull_future.result() # Block until the shutdown is