Internal communication between two Azure container app

Question

Internal communication between two Azure container app

Santi Cuni 0

I need urgent support because, since yesterday, I have been working to build up two Azure container apps inside the same Azure container environment, and even though all the checks have been done, there is no communication. My email is <PII removed>. I am available right now to talk. I need to go ahead. I have also created two times everything, but nothing changed.

Santi Cuni 0 Reputation points

2026-03-17T07:13:54.6+00:00

I have already done all the checks suggested by the AI Assistant. This is the reason why I have opened the case. I need someone with skills to support me. Thanks
Santi Cuni 0 Reputation points

2026-03-17T07:31:10.32+00:00
This is what I have seen from the console "NFO: Connecting to the container 'rag-frontend'...

INFO: Successfully connected to container: 'rag-frontend'. [ Revision: 'rag-frontend--0000010', Replica: 'rag-frontend--0000010-5f984c689f-djtqv'].

python3

Python 3.11.15 (main, Mar 3 2026, 20:22:58) [GCC 14.2.0] on linux

Type "help", "copyright", "credits" or "license" for more information.

import requests

url = "http://rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io:8000"

r = requests.get(url)

Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 204, in _new_conn

sock = connection.create_connection( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/util/connection.py", line 85, in create_connection

raise err

File "/usr/local/lib/python3.11/site-packages/urllib3/util/connection.py", line 73, in create_connection

sock.connect(sa)

TimeoutError: [Errno 110] Connection timed out

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/urllib3/connectionpool.py", line 787, in urlopen

response = self._make_request( ^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/connectionpool.py", line 493, in _make_request

conn.request(

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 500, in request

self.endheaders()

File "/usr/local/lib/python3.11/http/client.py", line 1318, in endheaders

self._send_output(message_body, encode_chunked=encode_chunked)

File "/usr/local/lib/python3.11/http/client.py", line 1078, in _send_output

self.send(msg)

File "/usr/local/lib/python3.11/http/client.py", line 1016, in send

self.connect()

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 331, in connect

self.sock = self._new_conn() ^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 213, in _new_conn

raise ConnectTimeoutError(

urllib3.exceptions.ConnectTimeoutError: (<HTTPConnection(host='rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io', port=8000) at 0x70a9e60313d0>, 'Connection to rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io timed out. (connect timeout=None)')

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/requests/adapters.py", line 644, in send

resp = conn.urlopen( ^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/connectionpool.py", line 841, in urlopen

retries = retries.increment( ^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/util/retry.py", line 535, in increment

raise MaxRetryError(_pool, url, reason) from reason # type: ignore[arg-type] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io', port=8000): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<HTTPConnection(host='rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io', port=8000) at 0x70a9e60313d0>, 'Connection to rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io timed out. (connect timeout=None)'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

File "/usr/local/lib/python3.11/site-packages/requests/api.py", line 73, in get

return request("get", url, params=params, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/api.py", line 59, in request

return session.request(method=method, url=url, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/sessions.py", line 589, in request

resp = self.send(prep, **send_kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/sessions.py", line 703, in send

r = adapter.send(request, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/adapters.py", line 665, in send

raise ConnectTimeout(e, request=request)

requests.exceptions.ConnectTimeout: HTTPConnectionPool(host='rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io', port=8000): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<HTTPConnection(host='rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io', port=8000) at 0x70a9e60313d0>, 'Connection to rag-backend.internal.livelybeach-5e3ae55a.switzerlandnorth.azurecontainerapps.io timed out. (connect timeout=None)'))

KeyboardInterrupt"
Santi Cuni 0 Reputation points

2026-03-17T08:13:22.08+00:00
look at the logs: "# python3

Python 3.11.15 (main, Mar 3 2026, 20:22:58) [GCC 14.2.0] on linux

Type "help", "copyright", "credits" or "license" for more information.

import requests

requests.get("http://rag-backend:8000", timeout=5)

Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 204, in _new_conn

sock = connection.create_connection( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/util/connection.py", line 85, in create_connection

raise err

File "/usr/local/lib/python3.11/site-packages/urllib3/util/connection.py", line 73, in create_connection

sock.connect(sa)

TimeoutError: timed out

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/urllib3/connectionpool.py", line 787, in urlopen

response = self._make_request( ^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/connectionpool.py", line 493, in _make_request

conn.request(

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 500, in request

self.endheaders()

File "/usr/local/lib/python3.11/http/client.py", line 1318, in endheaders

self._send_output(message_body, encode_chunked=encode_chunked)

File "/usr/local/lib/python3.11/http/client.py", line 1078, in _send_output

self.send(msg)

File "/usr/local/lib/python3.11/http/client.py", line 1016, in send

self.connect()

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 331, in connect

self.sock = self._new_conn() ^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/connection.py", line 213, in _new_conn

raise ConnectTimeoutError(

urllib3.exceptions.ConnectTimeoutError: (<HTTPConnection(host='rag-backend', port=8000) at 0x727debd4e490>, 'Connection to rag-backend timed out. (connect timeout=5)')

The above exception was the direct cause of the following exception:

Traceback (most recent call last):

File "/usr/local/lib/python3.11/site-packages/requests/adapters.py", line 644, in send

resp = conn.urlopen( ^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/connectionpool.py", line 841, in urlopen

retries = retries.increment( ^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/urllib3/util/retry.py", line 535, in increment

raise MaxRetryError(_pool, url, reason) from reason # type: ignore[arg-type] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='rag-backend', port=8000): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<HTTPConnection(host='rag-backend', port=8000) at 0x727debd4e490>, 'Connection to rag-backend timed out. (connect timeout=5)'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

File "/usr/local/lib/python3.11/site-packages/requests/api.py", line 73, in get

return request("get", url, params=params, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/api.py", line 59, in request

return session.request(method=method, url=url, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/sessions.py", line 589, in request

resp = self.send(prep, **send_kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/sessions.py", line 703, in send

r = adapter.send(request, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File "/usr/local/lib/python3.11/site-packages/requests/adapters.py", line 665, in send

raise ConnectTimeout(e, request=request)

requests.exceptions.ConnectTimeout: HTTPConnectionPool(host='rag-backend', port=8000): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<HTTPConnection(host='rag-backend', port=8000) at 0x727debd4e490>, 'Connection to rag-backend timed out. (connect timeout=5)')".

the frontend can't reach the backend. This is my dockerfile and my docker compose

FROM python:3.11-slim COPY . /app/Production ENV PYTHONPATH=/app WORKDIR /app/Production/backend/API_backend RUN apt-get update && apt-get install -y curl RUN pip install --no-cache-dir -r requirements.txt CMD ["uvicorn", "backend_main_sanitas:app", "--host", "0.0.0.0", "--port", "8000"] services: backend_sanitas: build: context: . dockerfile: Dockerfile_backend env_file: .env environment: - PYTHONPATH=/app ports: - "8000:8000" restart: unless-stopped healthcheck: test: ["CMD", "curl", "-f", "http://localhost:8000/docs"] interval: 10s timeout: 5s retries: 5 frontend_sanitas: build: context: . dockerfile: Dockerfile_frontend env_file: .env environment: - PYTHONPATH=/app ports: - "8501:8501" depends_on: backend_sanitas: condition: service_healthy restart: unless-stopped
Siddhesh Desai 4,895 Reputation points Microsoft External Staff Moderator

2026-03-24T10:39:46.93+00:00

Hi, apologies for delayed response, I have escalated your case to backend team, as it requires backend intervention. I'll let you know once I get a response, I'll keep updating you the status of the case on Email
Siddhesh Desai 4,895 Reputation points Microsoft External Staff Moderator

2026-03-24T10:59:58.3233333+00:00
Hi @Santi Cuni The error requests.exceptions.ConnectTimeout suggests that the HTTP connection to the rag-backend service on port 8000 could not be established within the timeout period.

This might be caused by:

The rag-backend service is not running. The service is not accessible due to network issues. The hostname rag-backend is not resolving correctly.

Dockerfile Setup:

The Dockerfile is building an environment for a FastAPI application using Uvicorn.

The issue could be related to how the backend service is deployed or networked within Docker.

Steps to Resolve:

1. Verify Backend Service:

Ensure that the rag-backend service is running and accessible on port 8000.

If the service is running in Docker, check the container status:

docker ps

Confirm the logs of the backend container:

docker logs

2. Check Networking:

If using Docker Compose, ensure that both the service making the request and the rag-backend service are in the same network.

Verify the service name rag-backend is correctly defined in your Docker Compose file (if applicable).

3. Test Connectivity:

From within the container making the request, test connectivity to the backend service:

curl http://rag-backend:8000

If the curl command also times out, the issue is likely with the backend service or network configuration.

4. Update Dockerfile:

Ensure the backend service is correctly set up to listen on all interfaces (0.0.0.0). This is already handled in your

CMD uvicorn backend.main:sanitas_app --host 0.0.0.0 --port 8000

5. Increase Timeout:

Temporarily increase the timeout in your Python script while debugging:

requests.get("http://rag-backend:8000", timeout=10)

6. Verify Dependencies:

Ensure all required dependencies are installed:

apt-get update && apt-get install -y curl pip install --no-cache-dir -r requirements.txt

7. Check Logs and Errors:

Review the backend service logs to identify any issues preventing it from starting or responding.

If the issue persists, please provide additional details about your deployment setup (e.g., Docker Compose file, network configuration) for further assistance.

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Santi Cuni 0 Reputation points

2026-03-17T07:13:54.6+00:00

I have already done all the checks suggested by the AI Assistant. This is the reason why I have opened the case. I need someone with skills to support me. Thanks
Siddhesh Desai 4,895 Reputation points Microsoft External Staff Moderator

2026-03-24T10:39:46.93+00:00

Hi, apologies for delayed response, I have escalated your case to backend team, as it requires backend intervention. I'll let you know once I get a response, I'll keep updating you the status of the case on Email

Answer 1

Hi @Santi Cuni

Thank you for sharing how you were able to resolve the issue. As you identified, the environment variable used for frontend‑to‑backend communication was being overwritten because load_dotenv(override=True) was configured in both containers. Each time the Python application loaded, this caused the correct FQDN to be replaced with the local value. Once you removed the override=True parameter, the correct FQDN was retained and the communication started working as expected.

We truly appreciate the time and effort you invested in troubleshooting and resolving the issue independently, as well as for sharing the root cause with us.

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Internal communication between two Azure container app

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