ENXIO Error When Opening Host FIFO File from Docker Container

[san-tekart]

Description:
I am experiencing an issue where my application, running inside a Docker container, fails to send DLT logs to the dlt-daemon running on the host system. Specifically, the application encounters an ENXIO (No such device or address) error when attempting to open the DLT daemon FIFO (/tmp/dlt) for writing, despite the FIFO being correctly mounted and accessible within the container. The following message is outputted when executing dlt_register_application.

"[846134.595925]DLT 30~INFO ~FIFO /tmp/dlt cannot be opened. Retrying later..."

Steps to Reproduce:

1. Start dlt-daemon on the host with the FIFO file located at /tmp/dlt.
2. Run a Docker container with the host's /tmp/dlt directory mounted inside the container using -v /tmp/dlt:/tmp/dlt.
3. Inside the Docker container, attempt to register a DLT application and send logs via the dlt_register_app function, which internally tries to open the FIFO file with open(dlt_daemon_fifo, O_WRONLY | O_NONBLOCK | O_CLOEXEC).

Expected Behavior:
The application running inside the Docker container successfully opens the FIFO file and sends logs to the dlt-daemon running on the host.

Actual Behavior:
The open() call for the FIFO file fails with errno set to 6 (ENXIO), indicating "No such device or address", preventing the application from sending logs to the host's dlt-daemon.

Environment:

• DLT Daemon version: [specify version]
• Docker version: [specify version]
• Host OS: [specify OS and version]
• Container base image: [specify image]

Additional Context:

• The FIFO file /tmp/dlt exists on the host and is correctly identified as a FIFO.
• The same FIFO file is mounted inside the Docker container with correct permissions (prw-rw-rw-).
• Manual tests with echo "test" > /tmp/dlt from the host work as expected, indicating that the dlt-daemon is correctly processing logs sent to the FIFO.
• Similar manual tests from within the Docker container do not show any visible error but do not result in logs being processed by the dlt-daemon.

I suspect this issue may involve how Docker containers interact with FIFO files or a potential race condition with dlt-daemon initialization. Any insights or suggestions on how to address this problem would be greatly appreciated.

[minminlittleshrimp]

Hello @san-tekart
this is a known issue and we have some idea to overcome. I will create PR for this as a request.
Nice to have this issue on my list, thank you