Airflow live executor logs with DaskExecutor - airflow

Question

I have an Airflow installation (on Kubernetes). My setup uses DaskExecutor. I also configured remote logging to S3. However when the task is running I cannot see the log, and I get this error instead:
*** Log file does not exist: /airflow/logs/dbt/run_dbt/2018-11-01T06:00:00+00:00/3.log
*** Fetching from: http://airflow-worker-74d75ccd98-6g9h5:8793/log/dbt/run_dbt/2018-11-01T06:00:00+00:00/3.log
*** Failed to fetch log file from worker. HTTPConnectionPool(host='airflow-worker-74d75ccd98-6g9h5', port=8793): Max retries exceeded with url: /log/dbt/run_dbt/2018-11-01T06:00:00+00:00/3.log (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f7d0668ae80>: Failed to establish a new connection: [Errno -2] Name or service not known',))
Once the task is done, the log is shown correctly.
I believe what Airflow is doing is:
for finished tasks read logs from s3
for running tasks, connect to executor's log server endpoint and show that.
Looks like Airflow is using celery.worker_log_server_port to connect to my dask executor to fetch logs from there.
How to configure DaskExecutor to expose log server endpoint?
my configuration:
core remote_logging True
core remote_base_log_folder s3://some-s3-path
core executor DaskExecutor
dask cluster_address 127.0.0.1:8786
celery worker_log_server_port 8793
what i verified:
- verified that the log file exists and is being written to on the executor while the task is running
- called netstat -tunlp on executor container, but did not find any extra port exposed, where logs could be served from.

Answer 1

UPDATE
have a look at serve_logs airflow cli command - I believe it does exactly the same.
We solved the problem by simply starting a python HTTP handler on a worker.
Dockerfile:
RUN mkdir -p $AIRFLOW_HOME/serve
RUN ln -s $AIRFLOW_HOME/logs $AIRFLOW_HOME/serve/log
worker.sh (run by Docker CMD):
#!/usr/bin/env bash
cd $AIRFLOW_HOME/serve
python3 -m http.server 8793 &
cd -
dask-worker $#