x-yuri/docker: cron && tail -f.md

## docker: cron && tail -f.md

      
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              docker: cron && tail -f.md
            
          
    docker: cron && tail -f

If cron dies, the container keeps running.
docker-compose.yml:
services:
  cron:
    build: .
Dockerfile:
FROM ubuntu:23.04
COPY crontab .
RUN set -x \
    && apt-get update \
    && apt-get install cron \
    && crontab crontab \
    && touch /var/log/cron.log
CMD cron && tail -f /var/log/cron.log
crontab:
* * * * * date >>/var/log/cron.log 2>&1

$ docker-compose up

$ docker-compose ps
NAME                      COMMAND                  SERVICE             STATUS              PORTS
cron-experiments-cron-1   "/bin/sh -c 'cron &&…"   cron                running             

$ docker-compose exec cron ps -efH
UID          PID    PPID  C STIME TTY          TIME CMD
root          10       0  0 13:34 ?        00:00:00 ps -efH
root           1       0  0 13:34 ?        00:00:00 /bin/sh -c cron && tail -f /var/log/cron.log
root           8       1  0 13:34 ?        00:00:00   cron
root           9       1  0 13:34 ?        00:00:00   tail -f /var/log/cron.log

$ docker-compose exec cron pkill cron

$ docker-compose exec cron ps -efH
UID          PID    PPID  C STIME TTY          TIME CMD
root          28       0  0 13:36 ?        00:00:00 ps -efH
root           1       0  0 13:34 ?        00:00:00 /bin/sh -c cron && tail -f /var/log/cron.log
root           9       1  0 13:34 ?        00:00:00   tail -f /var/log/cron.log

$ docker-compose ps
NAME                      COMMAND                  SERVICE             STATUS              PORTS
cron-experiments-cron-1   "/bin/sh -c 'cron &&…"   cron                running