无法在kubernetes上运行cronjobs [英] Unable to run cronjobs on kubernetes
问题描述
我遇到一个问题,即kubernetes中的cronjob似乎不起作用. 下面是使用的测试Dockerfile
I'm having an issue whereby cronjob in kubernetes doesnt seem to work. Below is the test Dockerfile used
FROM debian:jessie
RUN apt-get update
RUN apt-get -y install --no-install-recommends cron
RUN echo 'PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin' | crontab
RUN echo '0-59/2 * * * 0-4 export ENV=dev RECIPIENT=email@example.com; echo "$(date) ${ENV} ${RECIPIENT}" >> /var/log/cron.log' | crontab
CMD ["cron", "-f", "-L", "15"]
使用本地docker运行上述dockerfile,我可以在日志文件中看到输出,但在kubernetes中看不到.检查了事件,但没有发现任何异常.
Using native docker to run the above dockerfile, I could see the output in the logfile but not in kubernetes. Checked the events but didn't notice anything unusual.
下面是所使用的复制控制器yaml文件
Below is the replicationcontroller yaml file used
apiVersion: v1
kind: ReplicationController
metadata:
labels:
name: cron-test
name: cron-test
spec:
replicas: 1
selector:
name: cron-test
template:
metadata:
labels:
name: cron-test
spec:
containers:
- name: cron-test
image: example/cron-test:latest
resources:
limits:
cpu: 100m
memory: 512Mi
imagePullPolicy: Always
谢谢
推荐答案
我可以通过切换Dockerfile使其正常工作
Somehow I got it working by switching the Dockerfile around
Dockerfile
Dockerfile
FROM debian:jessie
RUN apt-get update
RUN apt-get -y install --no-install-recommends cron
COPY . /src
WORKDIR /src
RUN cp run.sh /run.sh \
&& chmod a+x /run.sh \
&& touch /var/log/cron.log
CMD ["/run.sh"]
run.sh
#!/bin/sh
cat << EOF > /tmp/setup-env.sh
export ENV=dev
export RECIPIENT=email@example.com
EOF
crontab /src/crons.conf
exec cron -f -L 15
crons.conf
crons.conf
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
0-59/2 * * * 0-4 . /tmp/setup-env.sh ; echo "$(date) ${ENV} ${RECIPIENT}" >> /var/log/cron.log 2>&1
我的猜测是,因为crontab /src/crons.conf
在构建时运行,并且构建文件系统不同于运行文件系统,即使用本机docker(rootfs)进行构建并在kubernetes(overlayfs)上运行.
My guess is that because crontab /src/crons.conf
was running at build time and build file-system is different from running file-system i.e building with native docker (rootfs) and running it on kubernetes (overlayfs).
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