Docker Crontab - Time based DNS Filter

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1

I was planning on using crontab to setup a time based DNS Filter, but when I try to edit crontab, I get the following error:

crontab -e
update-alternatives: no alternatives for editor

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Is contab supported inside of docker?

2

You are missing (as stated) a text editor...

Install one of those and you'll be able to edit the crontab file.

I think nano will work good for you ...

Keep in mind that when and if the docker image is updated, your editor will be gone ...

6

If the image gets updated, will that remove the crontab edits that I input?

7

The best way to add a crontab is to create a file with whatever rules you want outside the container. Then volume mount that file into the container's /etc/cron.d/ folder:

docker run -v "$(pwd)/my-cron:/etc/cron.d/my-cron" ... the rest ... pihole/pihole

This style doesn't require an editor inside the container and will survive docker rm pihole ; docker run <new pihole> which is required as part of the updating procedure.

1 Like
8

I have followed your instructions, but can't seem to get it working...I am using docker compose and I added the following line to the pihole section and and re-ran docker-compose up which recreated the image.

volumes:
  - ${USERDIR}/docker/pihole/crontab/blockschedule:/etc/cron.d/blockschedule

I created a file named blockschedule:

#Block at 3:30 PM Monday To Thursday
30 15   * * 1-4 root    PATH="$PATH:/usr/local/bin/" pihole -b googlevideo.com m.youtube.com www.youtube.com ytimg.com ytimg.l.google.com
30 15   * * 1-4 root    PATH="$PATH:/usr/local/bin/" pihole --wild googlevideo.com ytimg.com

#Block at 8 PM Sunday
00 20   * * 0   root    PATH="$PATH:/usr/local/bin/" pihole -b googlevideo.com m.youtube.com www.youtube.com ytimg.com ytimg.l.google.com
00 20   * * 0   root    PATH="$PATH:/usr/local/bin/" pihole --wild googlevideo.com ytimg.com

#Unblock at 9 PM Sunday To Thursday
0 21    * * 0-4 root    PATH="$PATH:/usr/local/bin/" pihole -b -d googlevideo.com m.youtube.com www.youtube.com ytimg.com ytimg.l.google.com
0 21    * * 0-4 root    PATH="$PATH:/usr/local/bin/" pihole --wild -d googlevideo.com ytimg.com

Here is the directory of /etc/cron.d inside the pi-hole docker console

root@pihole:/etc/cron.d# ls -la
total 28
drwxr-xr-x  1 root root 4096 Feb  7 15:29 .
drwxrwxr-x  1 root root 4096 Feb  7 16:23 ..
-rw-r--r--  1 root root  102 Oct  7  2017 .placeholder
-rw-rw-r--+ 1 root root  767 Feb  7 16:22 blockschedule
-rw-r--r--  1 root root  712 Jan  1  2017 php
-rw-r--r--  1 root root 1704 Feb  3 18:05 pihole

I verified that I am able to see /etc/cron.d/blockschedule inside the pi-hole docker console. But when I go the the blacklist section in the PI-hole gui, none of the entries are showing up. What could I be missing?