Home » Eclipse Projects » Paho » Google API client breaks name resolution for python paho MQTT in a docker context
| Google API client breaks name resolution for python paho MQTT in a docker context [message #1835185] |
Thu, 26 November 2020 14:56 |
 W S
Messages: 2
Registered: November 2020 |
Junior Member |
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This question was initially posted at (I had to remove http everywhere and replace with XXX because as a new user I cannot post links) stackoverflow.com/questions/65023468/google-api-client-breaks-name-resolution-in-a-docker-context but I feel it may be more relevant in this forum.
My (home grade) code accesses the Google Calendar API and then publishes information it finds there to a MQTT bus (<del>the last part may not be relevant</del> it actually is).
It used to run as a service on my server and I decided to move it into a docker container (also on my server, I run many of them - both foreign ones from Docker Hob and my own).
**The problem I encounter is that calling the Google API libraries apparently breaks name resolution in paho MQTT when ran in a docker container.**
The following code works OK when started from the command line of my server (keys and endpoints redacted)
import googleapiclient.discovery
import paho.mqtt.publish
from google.oauth2 import service_account as google_oauth2_service_account
paho.mqtt.publish.single(
topic=f"testtopic",
payload="before google",
retain=True,
hostname='mqtt.mydomain'
)
print("before google")
google_credentials = google_oauth2_service_account.Credentials.from_service_account_info(
{
"type": "service_account",
"project_id": "myprojectid",
"private_key_id": "8...4",
"private_key": "-----BEGIN PRIVATE KEY-----\nM....Kag==\n-----END PRIVATE KEY-----\n",
"client_email": "smthg@smthg.iam.gserviceaccount.com",
"client_id": "1...9",
"auth_uri": "XXXXs://accounts.google.com/o/oauth2/auth",
"token_uri": "XXXXs://oauth2.googleapis.com/token",
"auth_provider_x509_cert_url": "XXXXs://www.googleapis.com/oauth2/v1/certs",
"client_x509_cert_url": "XXXXs://www.googleapis.com/robot/v1/metadata/x509/XXX%40dXXX.iam.gserviceaccount.com"
},
scopes=['XXXXs://www.googleapis.com/auth/calendar'],
subject='XXX@YYYY'
)
google_service = googleapiclient.discovery.build('calendar', 'v3', credentials=google_credentials, cache_discovery=False)
print("after google")
paho.mqtt.publish.single(
topic=f"testtopic",
payload="after google",
retain=True,
hostname='mqtt.mydomain'
)
print("before end of script")
In an MQTT explorer I see that the topic has been published to twice, with `before google` and `after google`, and the output is
before google
after google
end of script
So far, so good.
I then moved that code file into docker via the following `Dockerfile`:
FROM ubuntu:20.04
RUN apt update && DEBIAN_FRONTEND=noninteractive apt install -y python3-arrow python3-pip python3-paho-mqtt
RUN pip3 install google-api-python-client oauth2client
WORKDIR /app
COPY . .
CMD python3 googlecalendartest.py ; sleep 1000
The build went fine but the program crashes with (this is the only log)
before google
after google
Traceback (most recent call last):
File "googlecalendartest.py", line 32, in <module>
paho.mqtt.publish.single(
File "/usr/lib/python3/dist-packages/paho/mqtt/publish.py", line 227, in single
multiple([msg], hostname, port, client_id, keepalive, will, auth, tls,
File "/usr/lib/python3/dist-packages/paho/mqtt/publish.py", line 163, in multiple
client.connect(hostname, port, keepalive)
File "/usr/lib/python3/dist-packages/paho/mqtt/client.py", line 937, in connect
return self.reconnect()
File "/usr/lib/python3/dist-packages/paho/mqtt/client.py", line 1071, in reconnect
sock = self._create_socket_connection()
File "/usr/lib/python3/dist-packages/paho/mqtt/client.py", line 3522, in _create_socket_connection
return socket.create_connection(addr, source_address=source, timeout=self._keepalive)
File "/usr/lib/python3.8/socket.py", line 787, in create_connection
for res in getaddrinfo(host, port, 0, SOCK_STREAM):
File "/usr/lib/python3.8/socket.py", line 918, in getaddrinfo
for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known
I **do see** that `testtopic` received a payload of `before google`, but the one after the Google API calls is not there anymore.
`socket.gaierror: [Errno -2] Name or service not known` suggests that `mqtt.mydomain` is not resolvable (I think).
**EDIT**: I added a `print(requests.get("h.../google.com").status_code)` call after the Google API part and it works, so resolution is fine.
It means that the resolution is broken only for paho MQTT
[Updated on: Thu, 26 November 2020 17:54] Report message to a moderator |
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