Best-practice container entrypoint script for CKI container images

The entrypoint script provides a best-practice container entrypoint script for CKI (Python) container images. It is configured via environment variables:

Variable Description
START_REDIS Start a Redis server
START_PHP Start PHP FastCGI process manager
START_APACHE Start Apache web server
START_CELERY_xxxx Start Celery workers with the given command line arguments, one worker per variable
START_FLASK Start the given Flask app via gunicorn (production) or the Flask devel server
START_PYTHON_xxxx Start Python modules with the given command line arguments, one module per variable
LOG_NAME Append all stdout/stderr output to /logs/$LOG_NAME-$HOSTNAME.log
LOG_USE_HOSTNAME If false, do not include the host name in the log file name, i.e. log to /logs/$LOG_NAME.log
KRB_REFRESH If true, start a krb_ticket_refresher process in the background

These variables should be set in the Containerfile, e.g.

The following example starts a Redis server, two celery workers and a Flask app:

ENV START_CELERY_MATCHER="--app pipeline_herder.worker --concurrency 1 --queues matching"
ENV START_CELERY_HERDER="--app pipeline_herder.worker --concurrency 1 --queues herding"
ENV START_FLASK=pipeline_herder.webhook
ENV LOG_NAME=pipeline-herder

# CMD [""]  # mostly not needed as already set for CKI Python image

In case a separate entrypoint script is needed, the chaining must happen via exec like


Otherwise, the process tree cannot be killed on failures!