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I created a docker image for a cron job (script backup.sh) - it copies files to the remote server for a backup. but first - when container starts I need to create ssh keys and add it to authorized_keys on the remote server, so I can connect via rsync.

I can't figure out how could I do two tasks on the container start - launch script authorize.sh and cron

  • I tried to call authorize.sh within the script backup.sh, but it would be called always at the same time in multiple containers and those ssh key overwrites each other, that's why I need to do it on container start, not inside the cron script

  • I can't call the script in the dockerfile on image build, as the remote server connections are passed as environment variables

  • I've tried instead of CMD ['crond', '-f', '-d', '8'] do CMD ['authorize.sh', '-f', '-d', '8'] and add crond -f inside the authorize script, but container stops after finishing authorize.sh

Dockerfile

FROM alpine:3.6

RUN apk update; \
    apk upgrade;

RUN apk add bash openssh-client sshpass rsync

RUN mkdir -p /var/export/

COPY backup.sh /usr/local/bin/backup.sh
RUN chmod +x /usr/local/bin/backup.sh

RUN echo '0 */8 * * *   /usr/local/bin/backup.sh' > /etc/crontabs/root

WORKDIR /var/export/

CMD ["crond", "-f", "-d", "8"]
hatto
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  • You can read more at https://stackoverflow.com/a/30209974/3220113. Does it help when you use `FROM centos:7` ? – Walter A Jul 03 '19 at 08:19

1 Answers1

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that is how Docker works , when the CMD command finished the container will be stopped.

you can add kind of loop or some command that will not finished at the end of your authorize.sh somthing like :

tail -f /dev/null
LinPy
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  • thanks @linSel, it works. actually it works even with crond -f, I don't understand why it didnt work the first time – hatto Jul 03 '19 at 09:33