cron job not running inside docker container on ubuntu -

i have simple dockerfile follows

from ubuntu:latest  add crontab /etc/cron.d/test-cron  run chmod a+x /etc/cron.d/test-cron run touch /var/log/cron.log  cmd cron && tail -f /var/log/cron.log 

and content of crontab file simple as

* * * * * root echo "hello world" >> /var/log/cron.log 2>&1 # empty line 

when run on local os x machine (with docker-machine running), works fine ("hello world" printed log file every minute). however, when try run on ubuntu machine, cron job not run (empty log file).

here's command use run container

docker build -t crontest . docker run --name cron crontest 

i not sure why case. wonder if wrong ubuntu box have (wrong time setting?). have tried restart machine no effect. have other docker containers running on ubuntu box , they're running fine.

any suggestion on debug/ fix hugely appreciated.

edit:

after going inside container (docker exec -it cron /bin/bash), can verify cron running there:

root@a2ad451af8d9:/# ps -ef | grep cron root         1     0  0 20:15 ?        00:00:00 /bin/sh -c cron && tail -f /var/log/cron.log root         6     1  0 20:15 ?        00:00:00 cron root         7     1  0 20:15 ?        00:00:00 tail -f /var/log/cron.log root        25    11  0 20:21 ?        00:00:00 grep --color=auto cron 

install rsyslog inside container apt-get install rsyslog , launch command rsyslogd before starting cron cron -l15 (maximum logging). watch file /var/log/syslog inside container see cron daemon's own log output. tell if there problem parsing crontab , will, in case, log entry every minute similar below if has registered , trying run job.

cron[16]: (root) cmd (echo "hello world" >> /var/log/cron.log 2>&1)