cloudinit how to schedule a periodic task while bootstrapping a vm

Question

While creating vm using Nova boot I am supplying it a user-data script (cloud-init script).

what I am wondering is, how can I specify in that cloud init script( or any other way to do it) :- to schedule a cron job to run every 2 hours

lets say I want to run "du -s njain/ " to find the size of my directory every 2 hours

I know "runcmd" can be used to do it once..but how do i make it run periodically ? du -s ../njain/

score 29 · Answer 1 · edited Sep 25 '17 at 09:27

29

it might be too late now, but the right way to do it through cloud-init is just to use the cloud-config write_files module and create a cron entry file in /etc/cron.d

for your example, the cloud-init userdata would look something like:

#cloud-config 

write_files:
  - owner: root:root
    path: /etc/cron.d/your_cronjob
    content: * */2 * * * [USER] du -s njain/

Note: you must replace [USER] with the user you'd like to run the cronjob as.

edited Sep 25 '17 at 09:27

George

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answered May 31 '16 at 08:18

cjdcordeiro

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Note that cron files must contain a trailing newline, otherwise you'll get an error: `content: "* */2 * * * [USER] du -s njain/\n"` – Paulo Pinto Jun 15 '20 at 15:00

score -12 · Answer 2 · edited Mar 05 '20 at 21:03

-12

rather than using cloud-init I used crontab, crontab can be used to schedule tasks periodically. Since i was not sure how to use cloud init to do this...I ended up making a image template with the crontab below

sudo crontab -e

edited Mar 05 '20 at 21:03

Aaron Gallick

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answered Mar 01 '15 at 07:18

user2574872

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The question is how to create a crontab via cloud-init not how to create a crontab. – Simon Banks Mar 10 '22 at 10:00

cloudinit how to schedule a periodic task while bootstrapping a vm

2 Answers2