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No output running /usr/sbin/crond in a Docker alpine container?

My simple Dockerfile seems to work, however I'm pretty sure I'm doing something wrong. The container log is empty (docker logs -f <container id>).

The crond command is running in foreground (-f), so why I can't see any ouput?

FROM alpine

RUN apk add --update --no-cache lftp mariadb-client

CMD ["/usr/sbin/crond", "-l", "2", "-f"]
Solution

  • This works for me.

    Your Dockerfile.

    docker build --tag=60404556 --file=Dockerfile .

# One terminal
docker run --rm --interactive --tty --name=crond 60404556
crond[1]: crond (busybox 1.31.1) started, log level 2
crond[1]: user:root entry:*/15  *   *   *   *   run-parts /etc/periodic/15min
crond[1]: user:root entry:0 *   *   *   *   run-parts /etc/periodic/hourly
crond[1]: user:root entry:0 2   *   *   *   run-parts /etc/periodic/daily
crond[1]: user:root entry:0 3   *   *   6   run-parts /etc/periodic/weekly
crond[1]: user:root entry:0 5   1   *   *   run-parts /etc/periodic/monthly
...

# Another term
docker container logs --follow crond
crond[1]: crond (busybox 1.31.1) started, log level 2
crond[1]: user:root entry:*/15  *   *   *   *   run-parts /etc/periodic/15min
crond[1]: user:root entry:0 *   *   *   *   run-parts /etc/periodic/hourly
crond[1]: user:root entry:0 2   *   *   *   run-parts /etc/periodic/daily
crond[1]: user:root entry:0 3   *   *   6   run-parts /etc/periodic/weekly
crond[1]: user:root entry:0 5   1   *   *   run-parts /etc/periodic/monthly
...