cki_entrypoint.sh

Best-practice container entrypoint script for CKI container images

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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:

#!/bin/bash
ENV START_REDIS=true
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 ["cki_entrypoint.sh"]  # 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

exec cki_entrypoint.sh

Otherwise, the process tree cannot be killed on failures!