Docker cron job - docker

Question

I need to schedule some cron jobs in docker/kubernetes environment, which will make some external service calls using curl commands. I was trying to use plain alpine:3.6 image but it doesn't have curl.
Any suggestion what base image will be good for this purpose? Also, it will be helpful if there are some examples.

Answer 1

Prepare your own docker image which will includes packages you need or just use something like this https://github.com/aylei/kubectl-debug

Answer 2

I am able to run curl as cronjob job using alpine image as
FROM alpine:3.6
RUN apk --no-cache add curl bash
RUN apk add --no-cache tzdata
ENV TZ=Asia/Kolkata
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ /etc/timezone
RUN mkdir -p /var/log/cron \
&& touch /var/log/cron/cron.log \
&& mkdir -m 0644 -p /etc/cron.d
ADD curlurl /etc/crontabs/root
CMD bash -c "crond -L /var/log/cron/cron.log && tail -F /var/log/cron/cron.log"
#ENTRYPOINT /bin/bash
Where curlurl is having simple curl command as cron job
* * * * * /usr/bin/curl http://dummy.restapiexample.com/api/v1/employees >> /var/log/cron/cron.log
# Leave one blank line below or cron will fail
This is working fine . But now I have tried to make alpine base image with push in private repo to avoid downloading every time. But it stopped working. How can i debug why cron job is not running anymore. Below is the way I have used.
BaseImage
FROM alpine:3.6
RUN apk --no-cache add curl bash
RUN apk add --no-cache tzdata
ENTRYPOINT /bin/bash
Docker for curl
FROM my/alpine:3.6
ENV TZ=Asia/Kolkata
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ /etc/timezone
RUN mkdir -p /var/log/cron \
&& touch /var/log/cron/cron.log \
&& mkdir -m 0644 -p /etc/cron.d
ADD curlurl /etc/crontabs/root
CMD bash -c "crond -L /var/log/cron/cron.log && tail -F /var/log/cron/cron.log"
After making it like this I am not able to get any cron output . Any suggestion on how can I debug it.